Neurodegeneration

Neurodegenerative Diseases

TanovaMed Neurodegeneration April 22, 2019April 29, 2019Brain diseases, loss of brain function

The world over, life expectancy is increasing due to various reasons such as better access to health services, improved nutrition and other positive lifestyle changes. It is therefore unfortunate that we have not found a way to stem the tide of increasing cases of neurodegenerative diseases. Nevertheless, scientists are working tirelessly to understand the etiology of brain deterioration that comes with aging in the hope of finding a cure for neurodegenerative diseases.

The brain is made up of billions of cells known as neurons which facilitate vital communications in the brain. These neurons are present at birth and continue forming during the early days of life. There has been a lot of controversy as to whether adults are able to form new neurons; it is now emerging that neurogenesis in adulthood is a possibility in certain conditions.

Neurodegenerative disease is a broad term used to define diseases that occur following the loss of function and death of neurons in the brain. They have a slow onset and arise in old age laying weight to the claim that aging is linked to cognitive deterioration. As much as the symptoms of degenerative diseases may vary, the changes at the cellular level are interlinked. Symptoms may be emotional or behavioral, they include: memory loss, anxiety, agitation, mood changes, changes in gait, depression and diminished quality of life among others. When it comes to causation, genetics and environmental factors play a key role, but this will vary from one disease to the other. Common degenerative diseases include: Alzheimer’s disease, Parkinson’s disease, Motor neuron disease, Huntington disease, Spinal Muscular Atrophy, Prion disease, Multiple sclerosis and ALS.

To better understand this, let us look at a few of these conditions, how they present, risk factors and possible treatments.

Parkinson’s Disease

Parkinson’s disease occurs when neurons in the substantia nigra die; this region of the brain sends communication to the basal ganglia to cause musculoskeletal movement. The substantia nigra releases dopamine that is sent to the basal ganglia to trigger movement. When neurons in this part of the brain die, a person will have symptoms such as: resting tremor, rigidity and difficult in making movements. Initiating movement is difficult and they may need assistance. The person suffering from this may also portray emotional symptoms such as depression and anxiety. With brain deterioration also come memory deficits, lack of focus, attention deficits and slowness in processing thoughts.

Huntington’s Disease

Similar to Parkinson’s, Huntington disease affects neurons in the basal ganglia. However, Huntington disease is genetic and associated with a genetic defect in chromosome 4. This causes protein build up in the brain which results in toxicity to the brain cells. Patients will present with excessive movement that is uncoordinated. They will also have facial grimacing, jerking movements and impaired gait. The patient will also struggle to make intentional movements. Other symptoms include irritability, anxiety and rapid mood changes.

Dementia

Most neurodegenerative diseases will cause memory loss. It is believed that as the brain shrinks, memories are subsequently lost. Alzheimer’s disease and Lewy body dementia are the most common forms of neurodegenerative dementias.

Alzheimer’s Disease

This disease will present with plaques that build up in the cerebral cortex and it presents with gradual memory loss that worsens with time. It affects people aged between 40-90 years. As it progresses, patients will develop other symptoms that include: diminished reasoning skills, diminished ability to talk, diminished motor-eye coordination and emotional instability. Science has shown that acetylcholinesterase inhibitors can slow the progression of this disease.

Treatment of neurodegenerative diseases

Most neurodegenerative diseases are lifelong, with patients being advised to seek palliative treatment. But a lot of research is going on in this area and promising a lot of hope. One of the pathways being considered is stem cell therapy to replace the dead neurons. This idea is still in the pre clinical stage. A four-step approach to address neurogenerative diseases involves the following:

Neuroprotection: measures to protect brain cells from neurodegradation

Neuroplasticity: stimulating neurons to form new connections to adapt to changes such as injuries

Neuroenhancement: measures to enhance cognitive functions

Neurogenesis: Triggering brain cells to regenerate

TanovaMed Neurodegeneration April 22, 2019May 20, 2019Brain deterioration, cognitive decline, neurodegeneration

What is neurodegeneration?

Previously, it was believed that human beings were born with the complete set of neurons that they would need for their entire lifetime and were incapable of forming new neurons later in life. But new evidence has contradicted this theory and we now know that human beings are capable of forming new neurons in later life. In this brief, we shall discuss what kills brain cells, the mechanisms through which this happens and the implications of brain deterioration.

Neurons are the basic working unit of the brain; they may also be called brain cells. They transmit information to other neurons, muscles or glands.

During intra uterine life and shortly after birth, the nervous system is created in humans with 50% more neurons. These extra neurons are degraded through a programmed cell death mechanism known as apoptosis. Later in life, neuronal death that is unprogrammed and deleterious can happen; this is referred to as necrotic cell death to differentiate it from apoptosis. It may occur following traumatic brain injury, inflammation, exposure to environmental toxins, infections or genetic mutations.

Neurodegeneration is the progressive degradation of brain cells through necrotic processes. When this happens, the brain loses some key functions such as memory, cognition, judgment and intelligence. Neurodegeneration is a key element in the development of several chronic illnesses that affect the brain such as Alzheimer’s, Parkinson’s, dementia and Huntington disease. As much as these diseases differ in their presentation, the changes that happen at a cellular level are closely interlinked. Understanding the causes of brain deterioration is helpful in ameliorating the above-mentioned diseases.

What causes neurodegeneration?

The real triggers for neurodegeneration are hazy; however, a few factors have shown a positive correlation. Scientists are continuously looking into these factors in the hope that they can find possible cures for neurodegenerative diseases. The key factors include aging, exposure to toxic substances, inflammation, infections, genetic mutations and traumatic injuries. We shall look at a few of these factors.

· Aging

There are quite a few theories that have attempted to explain cognitive decline as a person age. Some theorists have also argued against the notion that brain deterioration is a natural process of aging. Whichever the case is, we are aware that most degenerative diseases have a late onset making it apparent that brain deterioration has something to do with aging.

Aging is associated with mitochondrial mutations and oxidative stress which occur over time. These two factors have been linked to neurodegeneration. Loss of mitochondrial function can also contribute to an accumulation of toxins in the brain. These toxins can kill brain cells.

· Buildup of toxins in the brain

Toxins can accumulate in the brain for several reasons such as injury, inflammation and infections. Chemical toxicity results in necrotic cell death. For example, the buildup of proteins tau and amyloid in Alzheimer’s disease results in neurodegeneration.

· Genetic mutations

Researchers at the University of Michigan have discovered a lipid molecule PI(3,5)P2 that is vital for the survival of nervous system cells. When this molecule undergoes mutation or is absent, brain cells begin to die.

· Autophagic block

Autophagy is a process through which the body gets rid of damaged cells by delivering them to lysosomes for degradation. In autophagy, defective cells are pushed out, so the brain remains “clean.” But when autophagy has been blocked, normal cells are broken down and thrown out leading to neurodegeneration. Science has confirmed that mutations of autophagic cells promote neurodegeneration. Alzheimer’s disease and Parkinson’s disease are both linked to defects in the autophagic pathways.

It is clear that all these factors that cause brain cells to die are interrelated. In some cases, neurons begin to malfunction and lose communication with other neurons and glands. When this happens, the symptoms will be similar to those that appear when brain cells have been destroyed.

Implications of neurodegeneration

Neurodegeneration is the trigger for the development and progression of neurodegenerative diseases. In trying to find a cure for neurodegenerative diseases, scientists have been forced to investigate the process of reversing or inhibiting neurodegeneration.