Neurodegenerative Disease

What is Neurodegenerative Disease?

Neurodegenerative disease is an umbrella term for conditions which primarily affect the neurons in the human brain. The term neurodegeneration is a combination of two words - "neuro," referring to nervous system cells called neurons and "degeneration," referring to progressive deterioration or death. Therefore, neurodegeneration is an age-associated progressive deterioration or death of neuronal (brain) structures and functions ultimately leading to cognitive disability and dementia. Alzheimer's disease, Parkinson's disease and Huntington’s disease are the most common neurodegenerative diseases.

• Huntington’s Disease:  A neurodegenerative disease that can be passed on from parent to child and affects the basal ganglia, leading to problems with moving too much
• Alzheimer’s Disease:  Neurodegenerative diseases that mainly lead to memory problems
• Parkinson’s Disease:  A neurodegenerative disease whose main symptoms are related to problems with movement, due to neuron death in the substantia nigra

All three conditions involve progressive brain deterioration or degeneration and although they have different clinical features, the cellular degeneration appears to be similar. For example, Parkinson's disease affects the basal ganglia of the brain, depleting it of dopamine, leading to stiffness, rigidity and tremors in the major muscles of the body. Alzheimer's disease is caused by deposits of tiny protein plaques that damage different parts of the brain and lead to progressive loss of memory. Huntington's disease is a genetic disorder that affects major muscles of the body leading to progressive muscle and coordination decline and eventually death.

Less than 5% of neurodegenerative diseases are caused by genetic mutations, while the remainder are thought to be caused by either a build-up of toxic proteins in the brain or loss of mitochondrial function, which eventually leads to the creation of damaging toxic substances in the brain. Scientists tend to agree that the result of the toxic proteins and substances cause a programmed cell death, which is deliberate suicide of the cell for the purpose of protecting other nearby neurons from these toxic substances.

Dementias are responsible for the greatest burden of neurodegenerative diseases, with Alzheimer’s representing approximately 60-70% of dementia cases. In general, dementia is the term for memory loss with the most common type being Alzheimer’s disease.

Every type of dementia is a result of neurodegeneration (shrinking of the brain). Shrinking is caused by a lot of neuronal death occurring throughout the brain. Because of the large number of neurons dying, people with dementia not only start losing their memories, but they eventually lose their ability to move, communicate, and even think properly