1. Internal Carotid Arteries

Internal carotid arteries consist of the left internal carotid artery and the right internal carotid artery which run along the inner side of the front of the neck towards the brain.

Internal carotid arteries originate from the common carotid arteries at the level of the thyroid cartilage. Common carotid arteries generate both internal and external carotid arteries.

• What Happens If There Is a Stroke in Internal Carotid Arteries?

A stroke affecting the internal carotid arteries will result in a lack of blood supply to the areas controlling vision, speech, and sensations.

2. Vertebral Arteries

Vertebral arteries consist of the left vertebral artery and the right vertebral artery which run along the back of the neck toward the skull where they both merge to form the basilar artery.

The basilary artery is responsible for the supply of blood to the brainstem, cerebellum, the posterior part of the brain, and also the upper part of the spinal cord.

Vertebral arteries are originated from the subclavian arteries that originate from the aortic arch (left subclavian artery) and the brachiocephalic artery (right subclavian artery).

• What Happens If There Is a Stroke in Vertebral Arteries?

A stroke affecting the vertebral arteries will result in a lack of blood supply to the areas controlling muscle movements and coordination, speech and vision, and alertness.

3. What Is the Circle of Willis?

The circle of Willis is formed by the meeting of the internal carotid arteries and the vertebral arteries at the base of the brain.

From the circle of Willis 3 major arteries are originated: the anterior cerebral artery (ACA), the middle cerebral artery (MCA), and the posterior cerebral artery (PCA).

4. What Does the Anterior Cerebral Artery Supply?

The anterior cerebral arteries (left and right) are connected by the anterior communicating artery and supply blood to the frontal lobes and the superior parietal lobes of the brain through their cortical and central branches.

The cortical branches of the anterior cerebral arteries supply blood to:

• The olfactory cortex, gyrus rectus and medial orbital gyrus through its orbitofrontal branches
• The corpus callosum, the cingulate gyrus, the medial frontal gyrus, and the paracentral lobule through its frontal lobe branches
• The praecuneus through its parietal branches. 

The central branches of the anterior cerebral arteries supply blood to the deep cerebral structures such as the rostrum of the corpus callosum and surrounding structures.

• What Happens If There Is a Stroke in Anterior Cerebral Arteries?

A stroke affecting the anterior cerebral arteries will result in a lack of blood supply to the areas controlling thinking, decision-making, and muscle strength of the legs [2].

5. What Does the Middle Cerebral Artery Supply?

The middle cerebral artery supplies blood to the cerebrum, the anterior temporal lobes, and the insular cortices through their cortical and central branches.

The cortical branches of the middle cerebral artery supply blood to the orbital, frontal, temporal, and parietal parts of the cerebral cortex.

The central branches of the middle cerebral artery supply blood to the deep structures of the brain such as the basal ganglia, and the caudate nucleus.

• What Happens If There Is a Stroke in Middle Cerebral Arteries?

A stroke affecting the middle cerebral arteries will result in the following symptoms:

· Hemiplegia (Paralysis on one side of the body)

· Blindness (the left or right side)

· Language problems, such as impairment in the ability to form words and sentences or understanding what others are saying.

· Changes in sensation

6. What Does the Posterior Cerebral Artery Supply?

The posterior cerebral artery supplies blood to the occipital lobes at the back of the brain and the posteromedial temporal lobes through their cortical and central branches.

The cortical branches include the thalamoperforating arteries, the thalamogeniculate arteries, the posterior choroidal arteries.

• The thalamoperforating arteries supply blood to the midbrain and the thalamus.
• The thalamogeniculate arteries supply medial and lateral geniculate nucleus and the pulvinar nuclei of the thalamus.
• The posterior choroidal arteries supply blood to the choroid plexus and the posterior part of the thalamus.

The central branches include the temporal branches, the occipital branches, the parieto-occipital artery, and the calcarine artery.

• The temporal branches supply blood to the uncus, and the parahippocampal, medial and lateral occipitotemporal gyri.
• The occipital branches supply blood to the cuneus, lingual gyrus, and posterolateral surface of the occipital lobe.
• The parieto-occipital artery supplies blood to the precuneus and cuneus.
• The calcarine artery supplies blood to the cuneus and lingual gyrus.

• What Happens If There Is a Stroke in Posterior Cerebral Arteries?

A stroke affecting the anterior cerebral arteries will result in a lack of blood supply to the areas controlling vision [3].

7. What Is a Stroke?

A stroke is the interruption of blood supply to the brain causing the death of brain cells. The longer is the lack of blood supply the more damage is caused to the brain.

The causes are associated with any event that causes the interruption of blood supply to the brain. The main causes are the following:

• Ischemic stroke which is due to a blockage of an artery (e.g., Atherosclerosis).
• Hemorrhagic stroke due to the bursting of an artery causing hemorrhagie that leads to significant loss of blood.

A transient ischemic attack is when the interruption of the blood supply is temporary.

Conclusion

The brain is supplied by the internal carotid arteries and the vertebral arteries that form the circle of Willis where the anterior cerebral arteries, middle cerebral arteries, and posterior cerebral arteries branch out to supply the different parts of the brain.

A stroke in one of these arteries or its branches will have specific symptoms that are associated with the control of specific functions within the body.

There are certain conditions that increase the risk of stroke including diabetes, hypertension (high blood pressure), high cholesterol levels in the blood, and irregular heartbeats.

The post What are the arteries that supply blood to the brain? appeared first on .

• Coronary Heart Disease
• Stroke
• Peripheral Arterial Disease

Every 36 seconds, one person dies from cardiovascular disease and 659,000 individuals die from heart diseases in the United States [1].

Heart disease is the leading cause of death in the United States.

Worldwide, stroke and ischemic heart disease were the leading cause of death in 2019 accounting for 8.89 million deaths [2].

1. What Is Cardiovascular System and Its Function?

The cardiovascular system is made of the heart, blood vessels, and the blood and is responsible for the following functions:

• Transport and supply the body’s tissues and organs with oxygen (O2) and nutrients.
• Transport hormones from secreting glands to target glands, tissues, and organs.
• Stabilize body temperature
• Maintain homeostasis (optimal functioning of the body such as fluid balance and body temperature).
• Transport of carbon dioxide (CO2) and metabolic waste (waste products from the metabolism of cells).

The blood vessels transport oxygen from the lungs through the respiratory circulation and nutrients from the digestive system.

Carbon monoxide is collected from tissues and organs by the blood and transported by the vessels to the lung for respiratory elimination.

Metabolic waste is also collected by the blood from the tissues and organs and transported by the vessels for elimination by the kidneys (urine), skin (sweating), and bowels.

The movement of blood within the body is ensured by the heart that works like the blood pump.

1.1. What Is Heart and Its Function?

The heart is a muscular organ that pumps blood carrying oxygen and nutrients to the body while also pumping out blood carrying dioxide of carbon and metabolic waste to organs such as lungs (CO2), skin, kidneys, and bowels.

• What Is the Structure of the Heart?

The human heart is a muscle made of 3 layers of tissue: the endocardium (inner layer), myocardium (middle layer), and the epicardium (outer layer).

The heart has 4 chambers known as the right atrium, left atrium, right ventricle, and left ventricle.

The right and left atria (plural of atrium) receive the blood from veins and the right and left ventricles to pump out the blood from the heart.

However, valves exist between the atria and ventricles and are known as atrioventricular valves.

The valve between the right atrium and the right ventricle is known as the tricuspid valve, while the one between the left atrium and the left ventricle is known as the mitral valve or cuspid valve.

The heart also contains valves that connect between the right ventricle and the pulmonary trunk known as the semilunar valve, and between the left ventricle and the aorta known as the aortic semilunar valve.

During the contraction of the ventricles, the tricuspid and mitral valves close to prevent the blood from flowing back into the atria, while the semilunar and aortic semilunar valves open to allow the blood to flow out through the aorta and the pulmonary trunk.

• What Is the Function of the Heart?

The heart works as a pump that allows the flow of blood from the right atrium to the right ventricle where it is pumped out into the pulmonary trunk (large blood artery) to the lungs.

At the same time, blood coming from the lungs flow into the left atrium then into the left ventricle where it is pumped out through the aorta (largest blood artery) to the systemic system (circulation carrying blood to organs and tissues in the body).

The contraction of the heart is known as systole, while the relaxation of the heart is known as diastole.

1.2. What Are Arteries?

Arteries are blood vessels that mainly carry oxygenated blood to organs and tissues of the body. The largest artery of the body is the aorta which carries blood from the left ventricle of the heart.

Arteries branch into smaller ones known as arterioles (smaller arteries) which further branch into capillaries involved in microcirculation.

1.3. What Are Veins?

Veins are blood vessels that mainly carry deoxygenated blood from organs and tissues of the heart. Examples of body veins include the cardiac veins.

Like Arteries veins also have venules (smaller veins), and capillaries.

2. Most Common Cardiovascular Diseases

2.1. Coronary Heart Disease (CHD)

Coronary Heart Disease, also known as coronary artery disease or ischemic heart disease, is associated with the reduction in blood supply to the heart muscle due to the thickening of the heart arteries.

The thickening of the heart arteries is due to atherosclerosis.

Atherosclerosis is a disease of elastic and large arteries caused by the formation of atheroma (plaque build-up). It is considered a chronic inflammatory as inflammation is involved in the process of atherosclerosis [4].

An atheroma is made of macrophages (type of immune cells), fibrous connective tissue, lipids, and calcium.

2.1.1. What Are the Symptoms of Coronary Heart Disease?

An acute coronary event may manifest with the following symptoms:

• Angina (feeling of chest pressure or tightness, burning)
• Dizziness
• Nausea
• Weakness
• Shortness of breath
• Neck pain

2.1.2. What Are the Risk factors for Coronary Heart Disease?

They are many factors that can increase the risk of coronary heart disease:

• Age
• High blood pressure
• Diabetes
• Obesity
• Lack of physical activity
• Smoking
• High levels of cholesterol in the blood
• Depression
• Family history

2.2. Stroke

A stroke is the interruption of blood supply to the brain causing the death of brain cells. The longer is the lack of blood supply the more damage is caused to the brain.

2.2.1. What Causes Stroke?

The causes are associated with any event that causes the interruption of blood supply to the brain. The main causes are the following:

• Ischemic stroke which is due to a blockage of an artery.
• Hemorrhagic stroke due to the bursting of an artery causing hemorrhagie.

A transient ischemic attack is when the interruption of the blood supply is temporary.

2.2.2. What Are the Symptoms of Stroke?

A stroke manifests with the following symptoms:

• Facial paralysis on one side
• Trouble speaking or understanding others
• Difficulty lifting arms due weakness and numbness

It is extremely important to call for an emergency to prevent further damage to the brain.

2.2.3. What Are the Risk Factors for Stroke?

The following conditions increase the risk of stroke:

• Hypertension (high blood pressure)
• Diabetes
• High cholesterol level in the blood
• Irregular heartbeats

2.3. What Is Peripheral Arterial Disease?

Peripheral Arterial Disease (PAD) is characterized by the blocking or narrowing of the blood vessels that carry blood to the legs.

The narrowing or blockage of the blood vessels is associated with atherosclerosis.

2.3.1. What Are the Symptoms of Peripheral Arterial Disease?

Due to the lack of blood supply to the legs, the following symptoms may manifest:

• Aches or cramps when walking (claudication) can happen to the hip, thigh, buttock, or calf
• Pain
• Weakness
• Hair loss in the legs
• Change in skin color of the affected leg
• Ulcers

2.3.2. What Are the Risk factors for Peripheral Arterial Disease?

The following factors can increase the risk of peripheral arterial disease:

• Age (above 60 years)
• Smoking
• Diabetes
• High cholesterol level in the blood
• Atherosclerosis

Conclusion

Heart disease is the leading cause of death and is associated with risk factors such as diabetes, unhealthy diet, overweight and obesity, excessive alcohol use, and lack of activity and exercise. Therefore, changes in lifestyles can significantly prevent the consequence of heart diseases.

The post What Are the Most Common Cardiovascular Diseases? appeared first on .

They are due to an urge or sensation that eases after performing the movement or the sound.

1. What Are the Types of Tics?

1.1. Primary Tics

• Transient tic disorder

Transient tic disorders are motor or vocal tics that last for less than a year.

• Chronic tic disorder

Chronic tic disorders are motor or vocal tics that last for more than a year.

• Adult-onset tic disorder

Adult-onset tic disorder is a recurrent childhood tic disorder; however, this subtype can be classified as a secondary tic disorder if it is due to acquired conditions such as encephalitis or head trauma [2].

• Tourette syndrome

Tourette syndrome is a neurological disease that affects certain parts of the brain (frontal subcortical circuits) responsible for voluntary movements [3].

It is characterized by both vocal and motor chronic tics that are sudden and repetitive such as blinking, clearing throat, grunting, or facial movements [4].

The genetic causes of Tourette’s Syndrome are unknown; however, some cases are associated with mutations in genes such as SLITRK1, CNTNAP2, and HDC.

SLITRK1 is a protein found in the membrane of neurons where it is involved in the regulation of synapses.

CNTNAP2 is a protein found in the membrane of the neurons where it plays a role in axons, while HDC is an enzyme involved in the function of the neurotransmitter histidine.

1.2. Secondary Tics

Secondary tics can be associated with the following disorders and conditions:

• Global Brain Developmental Disorder

This disorder is due to neurodevelopmental anomalies that lead to delays in the development of social and communication skills, such as autism, mental retardation (intellectual disability), and Pervasive developmental disorders (PDD).

• Infections

Examples of infections that affect the nervous system such as:

Viral Encephalitis

It is an inflammation of the brain caused by a viral infection.

Creutzfeldt–Jakob Disease

Creutzfeldt-Jacob disease is a progressive neurodegenerative disease affecting the brain and causing cognitive disorders such as memory loss, changes in behavior, and ataxia (uncoordinated movements)

The disease is due to the accumulation of a glycoprotein known as a prion, which functions in the brain are not well known [5].

Post-Streptococcal Disorders

Post-streptococcal disorders are autoimmune disorders that happen following infections with a type of bacteria known as Staphylococcus pyogenes.

• Genetic and Neurodegenerative Diseases

Wilson Disease

Wilson disease is a rare genetic disease characterized by the accumulation of copper in different parts of the body including the brain [6].

Huntington Disease

Huntington’s Disease is a neurodegenerative disease that affects the brain causing dementia, depression, difficulty focusing, involuntary movement, stumbling, and clumsiness  [7].

Neuroacanthocytosis

Neuroacanthocytosis is a group of genetic disorders characterized by anomalies of red blood cells (acanthocytosis) and movement disorders [8].

Hallervorden-Spatz Syndrome

Hallervorden-Spatz syndrome is a rare neurodegenerative disease characterized by the accumulation of iron in a part of the brain known as basal ganglia causing its damage [9].

• Drugs

Drugs such as caffeine [10], carbamazepine [11], cocaine [12], and lamotrigine [13].

• Toxins

Carbon monoxide poisoning [14].

• Brain injury

Head trauma [15], stroke (very low supply of oxygen to the brain), and ischemic encephalopathy (low supply of oxygen to the brain) [16].

• Immune Disorders of the Central Nervous System (CNS)

Antiphospholipid Antibody Syndrome

This syndrome is characterized by the production of antibodies against phospholipids in the body which increases the risk of blood clots and thrombosis [17].

Sydenham’s Chorea

Sydenham’s Chorea is a neurological disorder that affects children after an infection with a group A beta-hemolytic streptococcus (GABHS) [18].

• Psychiatric Disorders

Schizophrenia

Schizophrenia is a complex and severe mental health disorder that is classified as a type of psychosis. It is characterized by significant alterations in thoughts, perception, mood, and behaviors [19].

Psychogenic tics

Psychogenic tics are characterized by the sudden onset of brief motor tics that are due to an urge or sensation that can be suppressed. Psychogenic tics can be due to the body’s response to stress [20].

2. What Are the First Signs of Tics?

The initial evaluation of tics is difficult as other disorders may have similar signs such as attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), dyskinesis, stereotypies, or tourettism [21].

3. Do Tic Disorders Go Away?

An improvement in individuals affected by tics is generally observed by adolescence or early adulthood; therefore, waiting for a period of time can lessen the severity of the tics.

4. How Are Tics Treated?

Most individuals with tics do not seek treatment and education of the affected individual, family, and school environment (e.g., school personnel) about the causes of tics is the initial intervention [21].

This educational approach can prevent such as embarrassment, bullying, anger, self-harm, and social isolation.

However, if the tics become severe, non-pharmacological and pharmacological tic-suppressive medications are provided [21] [22].

• Non-pharmacological treatment

Behavioral Therapy

The aim of this therapy is to help the affected individuals to manage their tics and reduce their severity.

Habit Reversal

This intervention involves awareness training and competing response training.

The awareness training request from the affected individual to name the tic loud, while in the competing response training, the affected individual learns to do a new behavior every time the tic manifests [22].

• Pharmacological treatment

Although most prescribed medications for tics are not approved by the US FDA (Food and Drug Administration), Tics-suppressing medications such as alpha-2-agonists, dopamine blocking agents, are used for severe cases of tics to help individuals with tics with their daily life  [21].

Conclusion

Tic disorders can be primarily associated with Tourette’s syndrome but can also be related to physical and mental disorders, brain injury, drugs, or intoxications. Fortunately, an improvement in individuals affected by tics is generally observed by adolescence or early adulthood. Meanwhile, some of the affected individuals may suffer from embarrassment, bullying, and isolation, due to a lack of education on the causes of tics.

Therefore, is essential that the affected individual learn how to manage the tics in everyday life to reduce associated discomfort, stress, and anxiety.

The education of the family and people in close contact with the affected individual can also significantly reduce embarrassment and bullying through better understanding the difficulties facing an individual with a tic disorder.

The post How Do You Know If You Have a Tic Disorder? appeared first on .

• Mental health disorders such as schizophrenia, bipolar disorder, or psychosis
• Central nervous system disorders
• Neurological disorders
• Toxic and metabolic disorders and conditions
• Sleep deprivation or disorders
• Physical disorders such as diseases of vision and hearing organs
• Drugs such as some medications, alcohol, and hallucinogens (e.g., plant hallucinogens)
• Stroke
• Post-traumatic stress disorder (PTSD)

More information on the different types of hallucinations and their causes are provided below.

1- How Do You Know If You Hallucinate?

If an individual is hearing, seeing, smelling, tasting, and feeling (touch) things that are not real or do not exist outside their mind, this individual is likely to be experiencing hallucinations.

2- Is It Normal to Hallucinate?

Hallucinations can be a sign of mental health, neurological, and physical disorders. They can also be a sign of drugs consumption such as alcohol and hallucinogens.

3- What Are the 5 Types of Hallucinations?

There are 5 types of hallucinations that are not all due to psychotic disorders. Hallucinations can be caused by psychiatric and physical disorders [1].

3.1. What Are Auditory Hallucinations?

An auditory hallucination is the perception of sounds that are not real or do not exist outside of the mind of an individual [2]. They can be due to the following causes:

• Schizophrenia

Schizophrenia is a complex and severe mental health disorder that is classified as a type of psychosis. It is characterized by significant alterations in thoughts, perception, mood, and behaviors [3].

• Central Nervous System (CNS) Disorders

These are disorders that affect the brain known as encephalopathies or the spinal cord which are known as myelopathies.

• Psychotic Depression

Psychotic depression is a major depression associated with symptoms such as delusions, hallucinations, sleep issues, reduced motivation, and the capacity to experience a pleasure. It is often associated with bipolar disorder and major depression.

• Mania

Mania is a mood disorder characterized by an excessive level of energy, arousal, and enthusiasm.

• Post-Traumatic Stress Disorder (PTSD)

PTSD is an anxiety disorder associated with extremely stressful or distressing situations.

• Peripheral Lesions

Peripheral lesions are lesions that affect sensory or motor neurons of the peripheral nervous system (outside the brain and the spinal cord).

• Middle and Inner Ear Diseases

There are many diseases that affect tissues and organs of the middle and inner ear causing dizziness, inflammation, discharge, or hearing loss.

• Auditory Nerve Disease

This disorder affects the auditory nerve responsible for transmitting sound to the brain.

• Stroke

Stroke is a condition characterized by a very low blood supply to the brain which prevents its proper function.

• Arterio-vascular malformations

These are malformations that affect arteries and vessels responsible for blood supply to organs involved in hearing.

• Delirium

Delirium is a state of mental confusion lasting hours or days with alterations in consciousness, cognition, and attention.

• Dissociative Identity Disorder

Dissociative identity disorder or multiple personality disorder is a mental disorder characterized by the presence of at least two states of personality.

• Pontine Lesions

These are lesions that affect the pons region of the brainstem part of the brain which controls hearing, balance, involuntary actions, taste, and facial sensations.

• Temporal Lobe Epilepsy

Temporal lobe epilepsy is seizures that began in the temporal lobe and spread to other areas of the brain.

• Hallucinogens

Hallucinogens are chemical substances that modify the function of the nervous system causing cognitive, behavioral, perception, and consciousness changes. The most known hallucinogen is LSD (D-Lysergic acid diethylamide).

• Alcohol Hallucinosis

Alcohol Hallucinosis is a chronic state of alcoholic intoxication that affects the auditory system causing hallucinations.

• Syncope

Syncope or fainting is associated with low blood pressure resulting in a loss of consciousness and muscle strength.

3.2. What Are Visual Hallucinations?

A visual hallucination is the perception of images that are not real or do not exist outside of the mind of an individual such as crawling insects or small animals [4]. They can be due to the following causes:

• Neurologic Disorders

Neurologic Disorders are diseases that affect the nervous system including the central nervous system (brain and spinal cord) and the peripheric nervous system.

• Epilepsy

Epilepsy is associated with seizures that are due to abnormal electrical activity in the brain.

• Migraine

A migraine is a severe form of headache that manifests as an excruciating pain on one side of the head accompanied by a feeling of sickness and an increased sensitivity to light and sound.

• Glaucoma

Glaucoma is due to an excessive increase in the intraocular pressure within the eye that leads to damages including vision loss.

• Optic Nerve Disorders

This disorder affects the optic nerves responsible for transmitting visual information to the brain.

• Toxic Metabolic Disorders

Toxic metabolic disorders are characterized by the accumulation of products of metabolism (metabolites) in the tissues of the body leading to their damage. When affecting the eyes, it can cause damages that lead to anomalies with vision, such as visual hallucinations.

• Toxic Metabolic Encephalopathy

Toxic metabolic encephalopathy is also associated with the accumulation of metabolites in the brain leading to damages. If damaging parts of the brain involved in vision, it can cause anomalies with the vision such as visual hallucinations

• Schizophrenia

Schizophrenia is a complex and severe mental health disorder that is classified as a type of psychosis. It is characterized by significant alterations in thoughts, perception, mood, and behaviors [3].

• Hallucinogens

Hallucinogens are chemical substances that modify the function of the nervous system causing cognitive, behavioral, perception, and consciousness changes. The most known hallucinogen is LSD (D-Lysergic acid diethylamide).

• Sleep deprivation

Sleep deprivation is associated with insufficient (not enough) sleep that can be acute or chronic leading to reduced alertness, performance, and health issues.

• Drug and Alcohol Withdrawal Syndromes

These withdrawal syndromes are due to the changes in neurotransmission mediated by GABA.

• Retinal Diseases

Retinal diseases are disorders that affect the retina of the eye such as macular degeneration, intraocular tumors, retinal tear, and macular edema [5].

• Affective Disorders

Affective disorders are mental conditions characterized by changes in mood and emotions such as major depressive disorder.

• Conversion Disorders

Conversion disorders are mental conditions that cannot be explained by the presence of a disease or injury and which are characterized by paralysis, blindness, or other symptoms of the nervous system [6].

• Cataract Formation

A cataract is the clouding of the lenses of the eyes that help focus on objects at different distances.

• Enucleation

Surgical removal of the entire eye from its socket.

• Narcolepsy

Narcolepsy is a chronic disorder associated with the reduction in the ability to regulate the sleep-wake cycles.

• Choroidal Disorder

The choroidal disorder is due to damages to blood vessels in the eye known as choroid causing anomalies in vision.

• Sensory Deprivation

Sensory deprivation is an intentional reduction in the perception of one or more senses.

• Intense Emotional Experiences

These are life experiences that had significant emotional effects on the affected individuals such as a loss of a loved one, sexual abuse, or traumatic experiences.

3.3. What Are Olfactory Hallucinations?

An olfactory hallucination is the perception of smell that is not real or does not exist outside of the mind of an individual [7]. They can occur with several mental health disorders such as:

• Schizophrenia

Schizophrenia is a complex and severe mental health disorder that is classified as a type of psychosis. It is characterized by significant alterations in thoughts, perception, mood, and behaviors [3].

• Bipolar Disorder

Bipolar Disorder is a mood disorder characterized by mood swings between periods of depression (depressive episodes), and elevated mood that can be severe known as mania (manic episode) or less severe known as hypomania.

• Substance Abuse

Abusive consumption of drugs

• Eating Disorders

Eating disorders are characterized by unusual habits of excessive eating (e.g., binge eating disorder) or insufficient eating (e.g., anorexia).

3.4. What Are Gustatory Hallucinations?

A gustatory hallucination is the perception of taste (often metallic taste) that is not real or does not exist outside of the mind of an individual [8].

• Temporal Lobe Diseases

Temporal Lobe Disease causes seizures that began in the temporal lobe and spread to other areas of the brain. They can be caused by tumors, injury to the head, stroke, brain infections, or brain lesions

• Parietal Operculum Lesions

These are lesions that affect a part of the cerebral cortex causing the absence of speech.

3.5. What Are Tactile Hallucinations?

A tactile hallucination is the perception of touch that is not real or does not exist outside of the mind of an individual [7]. They can be due to the following causes:

• Substance Abuse

Abusive consumption of drugs

• Drug and Alcohol Withdrawal Syndromes

These withdrawal syndromes are due to the changes in neurotransmission mediated by GABA.

4- Can Stress Cause Hallucinations?

Auditory hallucinations have been associated with Post-Traumatic Stress Disorder (PTSD). PTSD is an anxiety disorder associated with extremely stressful or distressing situations.

6- What Causes Hallucinations in the Elderly?

Most of the hallucinations in the elderly are visual or auditory which can be due to the following causes:

• Side effects of Medications
• Diseases such as brain cancer, kidney, or liver failure.
• Dementia and Alzheimer Disease
• Grieving
• Impairment in hearing and vision
• Delirium

Conclusion

Hallucinations are very complex and their treatment depends on the cause of the hallucination.

The post What Causes the Brain to Hallucinate? appeared first on .

• Acetylcholine
• Dopamine
• Glutamate
• GABA
• Serotonin
• Norepinephrine
• Histamine

Neurotransmitters are produced by neurons and released in gaps that are found between neurons and between neurons and organs. These junctions are known as synapses.

When neurotransmitters are released in the synapses by a neuron, they go and bind to receptors on the receiving neuron or organ. It is like crossing from one side of a river to the other side.

This transition of neurotransmitters from one side to the other is known as neurotransmission.

As neurotransmitters are chemical messengers, they hold instructions such as excitatory (Doing) or inhibitory (Stop doing) information that is communicated and conveyed between neurons until they reach the target tissue or organ responsible for the execution of a specific action such as thinking, learning, emotions, memory, and movement.

I. What Is Acetylcholine?

Acetylcholine is an organic chemical involved in the transmission of instructions between neurons and muscles known as neuromotor or neuromuscular transmission, and between neurons that transmit information for brain organs and glands that are involved in attention, wakefulness, learning, memory (short-term memory), motivation, and mood and emotion [1].

1- What Is the Role of Acetylcholine in Disorders and diseases?

• Acetylcholine and Myasthenia Gravis

In Myasthenia Gravis, the body produces antibodies against acetylcholine receptors blocking the neuromuscular transmission resulting in muscles weakness and fatigue [2].

• Acetylcholine and Alzheimer’s Disease

As acetylcholine is essential for processing memory and learning, the loss of cholinergic neurons (neurons that uses acetylcholine for neurotransmission) contributes to the causes of Alzheimer’s Disease [3].

2- What Drugs Affect Acetylcholine?

There are drugs that promote the function of acetylcholine (agonists) such as nicotine, muscarine, and neostigmine, while others block its activity (antagonists) such as curare, atropine, scopolamine, and botulinum toxin.

In clinics, myorelaxants are used for the treatment of Myasthenia Gravis using inhibitors of cholinesterase, an enzyme that blocks the function of acetylcholine. For Alzheimer’s Disease, the cholinesterase inhibitor, rivastigmine, is used.

II. What Is Dopamine?

Dopamine is an organic chemical involved in the transmission of instructions between neurons to control movement and reward-motivated behavior, such as pleasure, craving, decision making based on rewards, associative learning (learning new things), and short-term memory [4].

1- What Is the Role of Dopamine in Diseases and disorders?

• Dopamine and Parkinson’s disease

Parkinson’s disease is due to the loss of neurons that secrete dopamine (substantia Negra region in the brain) and that control movement. As a result, symptoms such as trembling, stiffness, and slower movement are associated with this disease [5].

• Dopamine and Attention Deficit Hyperactivity Disorder (ADHD)

This disorder is associated with defects in dopamine neurotransmission resulting in reduced attention, short-term memory, and impulse control [6].

• Dopamine and Schizophrenia

Although the mechanism is not well known, the excessive use of dopamine stimulants, such as amphetamine, has been shown to induce schizophrenia [7].

2- What Drugs Affect Dopamine?

There are drugs that directly promote the function of dopamine (agonists) such as Deprenyl, while others directly block its activity (antagonists) such as chlorpromazine.

III. What is Glutamate?

Glutamate is the most abundant chemical messenger that is involved in excitatory neurotransmission which increases nerves impulses (action potential). It is implicated in cognitive activity, including memory and learning, the growth of neurons, and the formation of synapses [8].

1- What Is the Role of Glutamate in Diseases and disorders?

• Glutamate and Epileptic Seizures

Due to the high excitatory activity of glutamate (excitotoxicity), neurons are excessively stimulated resulting in uncontrolled shaking and loss of consciousness. If lasting for longer periods these epileptic seizures can lead to brain damage [9].

• Glutamate and Autism (Autism Syndrome Disorder)

This has been associated with alterations in glutamate function during the neurodevelopment of the embryo [10]. The born child has social and communication difficulties as well as limited and repetitive behavior.

• Glutamate and Stroke

Too much glutamate known as excitotoxicity can lead to the destruction of neurons resulting in stroke and death [11].

• Glutamate and Intellectual Disability

This has also been associated with alterations in glutamate function during the neurodevelopment of the embryo [12].

• Glutamate and Amyotrophic Lateral Disability (ALS)

ALS is a progressive degenerative disorder characterized by the loss of motor neurons (movement control) due to glutamate excitotoxicity [8].

• Glutamate and Alzheimer’s Disease

Glutamate excitotoxicity has been associated with the death of neurons, involved in learning and memory, and that is found in the cortex and hippocampus [13].

2- What Drugs Affect Glutamate?

There are drugs that promote the function of glutamate (agonists) such as NMDA (N-methyl-d-aspartate and AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid), while others block its activity (antagonists) such as ketamine and AP5 ((2R)-amino-5-phosphonovaleric acid).

IV. What is GABA?

GABA (Gamma-Aminobutyric acid) is a chemical messenger and the major inhibitor of neurotransmission by reducing nerves’ impulses (action potential). Therefore, it has an opposite action to that of glutamate, and therefore, ensures balanced neurotransmission. GABA is involved in self-control, emotions, and attention [14].

1- What Is the Role of GABA in disorders?

• GABA and Epileptic seizures

As GABA is an inhibitor of neurotransmission, the reduction in its level in neurons results in excitotoxicity as neurons are excessively stimulated resulting in uncontrolled shaking and loss of consciousness [15].  

• GABA and Sleep Disorder

GABA is known to favor sleep and alterations in its level in neurons will keep them stimulated which affects sleep [16].

• GABA and Anxiety Disorders

GABA has been shown to prevent the activation of the hypothalamus-pituitary gland-adrenal glands axis (HPA axis) that is involved in fear and anxiety. Reduction in the level of GABA promotes anxiety [17].

• GABA and Schizophrenia

Although the mechanism by which GABA is involved in schizophrenia is not well known, it is suggested that the reduction in GABA affects the function of the prefrontal cortex responsible for cognitive control (information processing and behavior) [18].

• GABA and Major Depression

The mechanism linking GABA and major depression is suggested to be like the one involved in anxiety disorders where a deficit in GABA increases the activation of the HPA axis [19].

• GABA and Autism (Autism Syndrome Disorder)

The link between GABA and autism may be due to defect in GABA function during the neurodevelopment of the embryo [20].

2- What Drugs Affect GABA?

There are drugs that promote the function of GABA (agonists) such as muscimol, while others block its activity (antagonists) such as bicuculine and tiagabine.

V. What is Serotonin?

Serotonin is a chemical messenger involved in the neurotransmission of information related to mood, reward, learning, memory, and cognition.

1- What Is the Role of Serotonin in disorders?

• Serotonin and Major depression

Although significant abnormalities in the function of serotonin were seen in depressed patients, the mechanism by which serotonin is involved in depression is not well known [21].

• Serotonin and Autism (Autism Syndrome Disorder)

The link between serotonin and autism may be due to alterations in serotonin function during the neurodevelopment of the embryo [22].

2- What Drugs Affect Serotonin?

There are drugs that directly promote the function of serotonin (agonists) such as lysergic acid diethylamide, fenfluramine, and MDMA (methylenedioxymethamphetamine), while others directly block its activity (antagonists) such as SSRI, ondansetron, and PCPA.

VI.  What is Norepinephrine?

Norepinephrine is a hormone and chemical messenger associated with the “fight-or-flight” response mediated by the HPA axis.

In temporary stressful situations, the hypothalamus secretes CRH (corticotropin-releasing hormone) to stimulate the secretion of ACTH (Adrenocorticotropic hormone) by the pituitary gland leading to the secretion of the hormone noradrenaline (norepinephrine) which instructs the brain and body for action [23].  

1- What Is the Role of Norepinephrine in disorders?

• Norepinephrine and Pheochromocytoma

Pheochromocytoma is a tumor found in the adrenal medulla where norepinephrine is produced. Because tumor cells produce large quantities of norepinephrine, symptoms such as hypertension as observed [24].

• Norepinephrine and Attention Deficit Hyperactivity Disorder (ADHD)

Although the mechanism between norepinephrine and ADHD is not well known, alterations in the processing of norepinephrine appear to be involved in impulsiveness and hyperactivity seen in ADHD [25].

2- What Drugs Affect Norepinephrine?

There are drugs that directly promote the function of epinephrine (agonists) such as moclobemide, idazoxan while others directly block its activity (antagonists) such as fusaric acid.

VII. What is Histamine?

Histamine is a well know actor in local immune responses, and is produced by mast cells and basophils; however, it is also an important neurotransmitter involved in itching following inflammation, and in the regulation of sleep-wakefulness cycle [26].

1- What Is the Role of Histamine in disorders?

• Histamine and Chronic Inflammation Diseases

Histamine is involved in the regulation of the function of immune cells which secrete cytokines that are involved in inflammation. Therefore, alteration of histamine levels is seen in several diseases, including atopic dermatitis, allergic asthma, and allergic rhinitis.

• Histamine and Allergies

Histamine is actively secreted by mast cells and basophils following their activation by allergens (substances causing allergies) which results in swelling, smooth muscle contraction, itching, and tachycardia.

• Mastocytosis

An excess of histamine is produced during mastocytosis which is characterized by increased proliferation of mast cells

2- What Drugs Affect Histamine?

There are drugs that directly block the function of histamine (agonists) such as diphenhydramine (Benadryl).

Conclusion

Neurotransmitters are essential for the function of the nervous system as they transmit information from the brain to other parts of the body and the other way around. Therefore, any alterations in their function have significant impacts on mental health and diseases.

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