Neurological disorders are conditions that affect the nervous system, which includes the brain, spinal cord, and nerves. These disorders can result in a wide range of symptoms, such as changes in sensation, movement, or cognition.

Some neurological disorders are considered psychiatric conditions, as they can affect mood, behavior, and cognitive function. Examples of these disorders include depression, anxiety, and schizophrenia.

Neurological disorders can arise from a variety of causes, including genetic factors, infections, injuries, and autoimmune disorders. Some neurological disorders may also be idiopathic, meaning that their exact cause is unknown.

Neurological and psychiatric conditions can be categorized based on their etiology and the nerve branch locations involved:

Etiology-based categorization:

1. Genetic disorders: These are caused by mutations or abnormalities in the genes responsible for normal brain development and function. Examples include Huntington’s disease, spinocerebellar ataxias, and fragile X syndrome.
2. Neurodegenerative disorders: These are characterized by progressive loss of nerve cells and/or their connections in the brain or other parts of the nervous system. Examples include Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis (ALS).
3. Traumatic brain injuries: These are caused by external forces that result in damage to the brain tissue, such as concussion, contusion, or penetrating injury.
4. Infections: These are caused by microorganisms that invade and damage the brain tissue, such as bacterial meningitis, viral encephalitis, or prion diseases.
5. Autoimmune disorders: These are caused by an abnormal immune response that targets and damages the nervous system, such as multiple sclerosis, neuromyelitis optica, or Guillain-Barré syndrome.

Nerve branch-based categorization:

1. Central nervous system (CNS) disorders: These affect the brain and/or spinal cord, which make up the CNS. Examples include stroke, traumatic brain injury, Alzheimer’s disease, and multiple sclerosis.
2. Peripheral nervous system (PNS) disorders: These affect the nerves that extend from the spinal cord to other parts of the body, which make up the PNS. Examples include carpal tunnel syndrome, peripheral neuropathy, and Guillain-Barré syndrome.
3. Autonomic nervous system (ANS) disorders: These affect the nerves that control involuntary functions of the body, such as heart rate, blood pressure, digestion, and sweating. Examples include autonomic neuropathy, dysautonomia, and postural orthostatic tachycardia syndrome (POTS).
4. Psychiatric disorders: These affect the emotional and cognitive functions of the brain, such as mood, perception, thought, and behavior. Examples include depression, anxiety, bipolar disorder, schizophrenia, and autism spectrum disorder.

Many neurological and psychiatric conditions can involve multiple nerve branch locations and have complex etiologies. Therefore, the categorization above is meant to provide a general framework for understanding these conditions and is not meant to be comprehensive or definitive

There are several factors that can increase the risk of developing neurological disorders, including:

• Age: many neurological disorders are more common in older adults
• Genetics: certain genetic mutations or family history can increase the likelihood of developing neurological disorders
• Environmental factors: exposure to toxins, infections, or traumatic brain injury can increase the risk of neurological disorders
• Lifestyle factors: poor diet, lack of exercise, and substance abuse can also increase the risk of neurological disorders.

There are many different neurological disorders, and they can be categorized based on their underlying cause or etiology. Some common neurological disorders and their etiologies include:

• Neurodegenerative disorders, such as Alzheimer’s disease and Parkinson’s disease, which involve the progressive loss of neurons and brain function over time.
• Stroke, which is caused by a disruption of blood flow to the brain
• Traumatic brain injury, which can result from a blow or jolt to the head
• Epilepsy, which is caused by abnormal electrical activity in the brain
• Multiple sclerosis, which is an autoimmune disorder that affects the nervous system.

Hormones can also be involved in the development of some neurological disorders. For example, hormones such as estrogen and testosterone can affect brain function and may play a role in the development of conditions such as Alzheimer’s disease and Parkinson’s disease

There are many genetic mutations that can increase the likelihood of developing neurological disorders. Some of these mutations are inherited, while others can occur spontaneously.

Common genetic mutations that have been associated with neurological disorders include:

• Mutations in the huntingtin (HTT) gene: These mutations are associated with Huntington’s disease, a progressive neurodegenerative disorder that affects movement, cognition, and behavior.
• Mutations in the amyloid precursor protein (APP) gene: These mutations can increase the production of beta-amyloid protein, which can lead to the development of Alzheimer’s disease.
• Mutations in the superoxide dismutase 1 (SOD1) gene: These mutations can cause damage to motor neurons, leading to the development of amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease.
• Mutations in the tau (MAPT) gene: These mutations are associated with several neurodegenerative disorders, including Alzheimer’s disease and frontotemporal dementia.
• Mutations in the Parkin (PARK2) gene: These mutations are associated with early-onset Parkinson’s disease.

Not all individuals with these mutations will develop neurological disorders, and other factors, such as environmental factors and lifestyle choices, can also play a role in the development of these disorders.

Amyloidosis can be a result of neurological disease or a contributing factor, depending on the specific type of amyloidosis and the underlying cause.

Amyloidosis is a condition where abnormal protein fragments called amyloid build up in various organs and tissues, including the nervous system. There are many different types of amyloidosis, and they can be caused by different underlying diseases or conditions.

In some cases, neurological diseases can lead to the development of amyloidosis. For example, Alzheimer’s disease is characterized by the accumulation of beta-amyloid protein in the brain, which can lead to the development of cerebral amyloid angiopathy (CAA), a form of amyloidosis that affects the blood vessels in the brain.

In other cases, amyloidosis can contribute to the development or progression of neurological disease. For example, transthyretin amyloidosis (ATTR) is a type of amyloidosis that affects the peripheral nerves and can lead to neuropathy, or nerve damage. In some cases, ATTR can also affect the heart, which can lead to heart failure and other cardiovascular problems.

Overall, the relationship between neurological disease and amyloidosis is complex and depends on the specific type of amyloidosis and the underlying cause.

There are several hormonal imbalances that have been associated with an increased likelihood of developing neurological diseases. Here are a few examples:

1. Thyroid hormone imbalances: Both hypothyroidism (low thyroid hormone levels) and hyperthyroidism (high thyroid hormone levels) have been associated with an increased risk of developing neurological diseases such as dementia, Alzheimer’s disease, and stroke.
2. Gonadal hormone imbalances: Changes in estrogen and testosterone levels have been linked to neurological diseases such as Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis. Women may have a higher risk of developing these diseases due to the decline in estrogen levels that occurs during menopause.
3. Adrenal hormone imbalances: Excessive production of cortisol (a hormone produced by the adrenal gland) has been linked to neurological diseases such as Alzheimer’s disease and depression.
4. Growth hormone imbalances: Excessive production of growth hormone has been linked to acromegaly, a condition that can lead to neurological complications such as pituitary tumors, cognitive impairment, and sleep apnea.

Hormonal imbalances alone are usually not enough to cause neurological disease. Other factors such as genetics, environmental factors, and lifestyle choices can also play a role.

The symptoms of neurological diseases can vary widely depending on the specific disease, its severity, and the individual. However, here are some common signs and symptoms that may indicate the presence of a neurological disease:

1. Changes in vision, such as blurry vision or loss of vision.
2. Muscle weakness or tremors.
3. Loss of sensation or numbness.
4. Difficulty with coordination or balance.
5. Seizures or convulsions.
6. Memory loss or difficulty with thinking or reasoning.
7. Headaches that are severe or persistent.
8. Dizziness or vertigo.
9. Mood changes, such as depression or anxiety.
10. Speech difficulties, such as slurring or stuttering.

If you are experiencing any of these symptoms, it is important to seek medical attention as soon as possible. Your healthcare provider may perform a neurological exam, which can include tests of reflexes, coordination, sensation, and cognitive function. Additional tests such as MRI or CT scans, blood tests, or nerve conduction studies

There are a variety of approved and undergoing novel therapies for neurological diseases. Here are some therapies for neurological diseases:

1. Biologic drugs for multiple sclerosis (MS): Drugs such as interferons, glatiramer acetate, and monoclonal antibodies are used to modify the immune system in MS patients.
2. Deep brain stimulation for Parkinson’s disease: Deep brain stimulation involves implanting electrodes in specific areas of the brain to help regulate abnormal brain activity and reduce symptoms of Parkinson’s disease.
3. Gene therapy for spinal muscular atrophy (SMA): The FDA has approved gene therapies such as Zolgensma and Spinraza for the treatment of SMA, a genetic disorder that affects the muscles and causes weakness and wasting.
4. Chimeric antigen receptor (CAR) T-cell therapy for certain types of brain cancer: CAR T-cell therapy involves modifying the patient’s own immune cells to target and destroy cancer cells.
5. Anti-amyloid drugs for Alzheimer’s disease: Drugs such as aducanumab are designed to target and remove amyloid plaques in the brain, which are a hallmark of Alzheimer’s disease.
6. Antidepressants for depression: Selective serotonin reuptake inhibitors (SSRIs) and other antidepressants can help alleviate symptoms of depression by regulating the levels of certain neurotransmitters in the brain.
7. Stem cell therapy for spinal cord injury: Stem cells are being studied as a potential therapy for spinal cord injury, as they have the ability to differentiate into different types of cells and promote tissue repair and regeneration.

These are just a few examples of the many novel therapies being developed for neurological diseases. It is important to note that some of these therapies may still be in clinical trials and not yet widely available to the public.

Stem cells are being studied as a potential therapy for various neurological disorders because of their ability to differentiate into different types of cells and promote tissue repair and regeneration. Here are some examples of how stem cells are being used to treat neurological disorders:

1. Parkinson’s disease: Researchers are investigating the use of stem cells to replace dopamine-producing neurons that are lost in Parkinson’s disease. The hope is that these new neurons will restore normal function and improve symptoms.
2. Multiple sclerosis (MS): Stem cells are being studied as a potential treatment for MS because they have the ability to regenerate myelin, the protective coating around nerve fibers that is damaged in MS.
3. Spinal cord injury: Stem cells are being studied as a potential therapy for spinal cord injury because they have the ability to differentiate into different types of cells and promote tissue repair and regeneration.
4. Alzheimer’s disease: Researchers are investigating the use of stem cells to replace damaged neurons in the brain and promote the growth of new brain cells.
5. Stroke: Stem cells are being studied as a potential therapy for stroke because they have the ability to differentiate into different types of cells and promote tissue repair and regeneration.

There are different types of stem cells being used in these studies, including embryonic stem cells, induced pluripotent stem cells (iPSCs), and adult stem cells. However, it is important to note that many of these studies are still in the experimental phase and have not yet been widely adopted as a standard therapy for these conditions

Stem cell therapy is a promising approach for the treatment of neurological disorders. The goal of this therapy is to use stem cells to replace or repair damaged or diseased cells in the nervous system. There are several different types of stem cells that can be used for this purpose, including:

1. Embryonic stem cells: These stem cells are derived from embryos and have the ability to differentiate into any type of cell in the body.
2. Induced pluripotent stem cells (iPSCs): These stem cells are created by reprogramming adult cells, such as skin cells, back into a pluripotent state.
3. Neural stem cells: These stem cells are found in the brain and have the ability to differentiate into different types of neural cells.
4. Mesenchymal stem cells: These stem cells are found in bone marrow and other tissues and have the ability to differentiate into a variety of cell types, including neural cells.

Stem cell therapy for neurological disorders involves transplanting stem cells into the affected area of the nervous system. The stem cells then differentiate into the specific types of cells needed to repair or replace damaged or diseased nerve cells in the nerve system!

There is ongoing research on the use of embryonic stem cells, sperm, and oocytes (not ovules) for stem cell therapy in a variety of conditions:

1. Embryonic stem cells: These are derived from embryos that are donated for research purposes. They have the potential to differentiate into any type of cell in the body and are being studied for a variety of conditions, including Parkinson’s disease, spinal cord injury, and heart disease.
2. Sperm: Sperm have been used to create pluripotent stem cells through a process called reprogramming. These cells have the potential to differentiate into any type of cell in the body and are being studied for a variety of conditions, including diabetes and heart disease.
3. Oocytes: Oocytes have also been used to create pluripotent stem cells through reprogramming. These cells have the potential to differentiate into any type of cell in the body and are being studied for a variety of conditions, including Alzheimer’s disease and spinal cord injury.

The use of embryonic stem cells and reprogrammed sperm and oocytes is still controversial, and there are ongoing ethical debates around their use in research and therapy. Additionally, many of these studies are still in the experimental phase and have not yet been widely adopted as a standard therapy for these conditions.

There are several drugs and hormone analogues that are approved or undergoing clinical trials for maintaining nerve cell health and preventing neurological disorders. Here are some examples:

1. Nerve growth factor (NGF) analogues: NGF is a protein that promotes the growth and survival of nerve cells. Analogues of NGF are being studied as potential therapies for Alzheimer’s disease, as they may help to protect and repair damaged nerve cells.
2. Insulin-like growth factor-1 (IGF-1) analogues: IGF-1 is a hormone that plays a role in the growth and survival of nerve cells. Analogues of IGF-1 are being studied as potential therapies for a variety of neurological disorders, including Alzheimer’s disease, Parkinson’s disease, and ALS.
3. HDAC inhibitors: Histone deacetylase (HDAC) inhibitors are a class of drugs that can modify the structure of chromatin and regulate gene expression. HDAC inhibitors are being studied as potential therapies for a variety of neurological disorders, including Huntington’s disease, Alzheimer’s disease, and multiple sclerosis.
4. BDNF mimetics: Brain-derived neurotrophic factor (BDNF) is a protein that promotes the growth and survival of nerve cells. Mimetics of BDNF are being studied as potential therapies for a variety of neurological disorders, including Alzheimer’s disease and depression.
5. GLP-1 receptor agonists: Glucagon-like peptide-1 (GLP-1) is a hormone that regulates glucose metabolism and has been shown to have neuroprotective effects. GLP-1 receptor agonists are being studied as potential therapies for a variety of neurological disorders, including Alzheimer’s disease and Parkinson’s disease.

Many of these therapies are still in the experimental phase and have not yet been widely adopted as standard therapies for these conditions. Additionally, clinical trials are ongoing to evaluate their safety and efficacy

There are several nerve growth factor (NGF) analogues that are currently being studied for their potential therapeutic use in neurological disorders. Here are some NGF analogues:

1. Tanezumab: Tanezumab is a monoclonal antibody that targets NGF and is being studied for its potential use in the treatment of chronic pain conditions such as osteoarthritis and chronic low back pain.
2. Fulranumab: Fulranumab is another monoclonal antibody that targets NGF and is being studied for its potential use in the treatment of chronic pain conditions.
3. NGF eye drops: NGF eye drops are being studied for their potential use in the treatment of neurotrophic keratitis, a rare eye condition that can cause vision loss.
4. Aducanumab: Aducanumab is a monoclonal antibody that targets amyloid beta, a protein that can build up in the brains of people with Alzheimer’s disease. Aducanumab has been shown to increase NGF levels in the brain, and is currently approved for use in the treatment of Alzheimer’s disease.

It’s important to note that while these therapies are being studied for their potential therapeutic use, they are not yet widely available or approved for use in clinical practice. Clinical trials are ongoing to evaluate their safety and efficacy

Histone deacetylase (HDAC) inhibitors are a class of drugs that target enzymes involved in the regulation of gene expression. They have been studied for their potential therapeutic use in cancer, neurodegenerative disorders, and other conditions. Here are some examples of common HDAC inhibitors:

1. Vorinostat (Zolinza): Vorinostat was the first HDAC inhibitor to be approved by the FDA for the treatment of cutaneous T-cell lymphoma.
2. Romidepsin (Istodax): Romidepsin is another HDAC inhibitor that is approved for the treatment of cutaneous T-cell lymphoma.
3. Belinostat (Beleodaq): Belinostat is an HDAC inhibitor that is approved for the treatment of peripheral T-cell lymphoma.
4. Panobinostat (Farydak): Panobinostat is an HDAC inhibitor that is approved for the treatment of multiple myeloma.
5. Valproic acid: Valproic acid is an HDAC inhibitor that is commonly used as an anticonvulsant in the treatment of epilepsy, but is also being studied for its potential use in cancer and other conditions.

HDAC inhibitors can have significant side effects and should only be used under the supervision of a healthcare professional. Clinical trials are ongoing to evaluate their safety and efficacy in various conditions

HDAC inhibitors can have various side effects, which may vary depending on the specific drug and the dose used. Some common side effects of HDAC inhibitors include:

1. Fatigue and weakness
2. Nausea and vomiting
3. Diarrhea or constipation
4. Loss of appetite and weight loss
5. Low blood cell counts (anemia, thrombocytopenia, leukopenia)
6. Increased risk of infection
7. Headaches
8. Skin rash or itching
9. Increased risk of bleeding
10. Electrolyte imbalances
11. Cardiac arrhythmias
12. Liver toxicity

Not all patients will experience all of these side effects, and some patients may not experience any side effects at all. However, it is important to talk to your healthcare provider if you experience any concerning symptoms while taking an HDAC inhibitor, as they can work with you to manage these side effects and monitor for any potential complications

Some common IGF-1 analogues include:

1. mecasermin (brand name: Increlex)
2. mecasermin rinfabate (brand name: Iplex)
3. mecasermin rinfabate recombinant (brand name: SomatoKine)
4. long-acting growth hormone releasing factor (GRF) analogues, such as tesamorelin (brand name: Egrifta)

These analogues are used to treat various medical conditions, such as growth hormone deficiency, insulin resistance, and muscle wasting disorders. They work by stimulating the production and release of insulin-like growth factor 1 (IGF-1), a hormone that plays an important role in growth, metabolism, and cell proliferation

Verified by: Rami Diab (May 5, 2023)

Citation: Rami Diab. (May 5, 2023). Neurological Disorders Overview, Risks, Novel Therapies. Medcoi Journal of Medicine, 9(2). urn:medcoi:article22305.