DEMENTIA

Dementia is a major neurocognitive disorder that extends to various degrees of severity from person to person. it is caused due to damage or loss of nerve cells or their connections in the brain.

Causes-

· Age

· Dementia in your family

· Illnesses including diabetes, Down syndrome, heart disease, and

· sleep apnea

· Depression

· poor diet, and lack of exercise

ALZHEIMERS

There are various types of dementia associated with various types of damage of brain cells in particular regions of the brain. For example ,in alzheimers, high levels of proteins like amyloid and tau inside and outside the brain cells make it hard for them to stay healthy and communicate with each other. The hippocampus is the center for learning and memory, and the brain cells in this region are often the first to be damaged. That’s why memory loss is one of the first symptoms of Alzheimer’s.

Genetic disorders

Even though we cant bring it down to one particular gene that causes Alzheimer’s, however, there is one gene called the Alipoprotein E (ApoE) gene that increases the risk of getting Alzheimer’s. This is the alipoprotein E (ApoE) gene

This gene gives instructions for making a protein called apolipoprotein E, which combines with lipids and fats in the body to form molecules called lipoproteins. These molecules are responsible for packaging cholesterol and other fats and carrying them through the bloodstream, as APOE is the principal cholesterol carrier in the brain. It is synthesized in the liver

The ApoE gene has three common variants - e2, e3 and e4. Each individual has two copies of the APOE gene, which may or my not be the same as each other. Therefore everyone is born with one of the six possible combinations: e2/e2, e2/e3, e3/e3, e2/e4, e3/e4 or e4/e4.

• The relatively rare APOE e2 gene can sometimes provide some protection against developing Alzheimer’s disease. Even if people with this gene do develop alzheimers, it occurs later in life as compared to people with other variants.

• The most common variant is the APOE e3 gene. Unlike the APOE e2 and APOE e4, APOE e3 does not play a role in increasing or decreasing the risk of developing Alzheimer’s. It plays a neutral role.

• 25-30% of the population have the APOE e4 gene and it occurs in about 40% of all people who develop late-onset Alzheimer’s. it has been has confirmed that APOE e4 leads to an increased risk of developing the disease, but the reason has still not been understood. People who inherit 1 or 2 copies of APOE e4 usually develop Alzheimer’s earlier as compared to those who don’t carry this variant.

An interesting fact is that Nigerian people have one of the highest observed frequency of the APOE4 allele in the entire world, however, Nigeria is among the countries with the least reported cases of alzheimers. This is thought to be because of their food habits and environmental and cultural factors.

PROTEIN DISORDERS

Neurofibrillary Tangles

Abnormal accumulations of a unique protein named tau inside the neuron causes neurofibrillary tangles. Structures called microtubules are present in healthy neurons; these microtubules support the neurons internally and also help in guiding nutrients and molecules from the cell body to axon and dendrites. Usually, in people without Alzheimer’s, tau binds with and stabilizes microtubules. However, in people with Alzheimer’s disease abnormal chemical changes lead to tau detaching from microtubules and sticking to other tau molecules, forming threads and eventually joining to form tangles inside neurons. These tangles and threads block the internal neuron’s transport system, harming the synaptic communication between neurons.

Amyloid Plaques

The beta amyloid protein is formed from the breakdown of a larger protein, amyloid precursor protein gives the beta-amyloid protein which plays a role in Alzheimer’s. it comes in several different forms that gets collected in between neurons. The beta-amyloid 42 form is confirmed to be especially toxic. This naturally occurring protein in abnormal levels in the Alzheimer’s brain start clumping together and form plaques that collect between neurons and disrupt cell function.

-Aalia Imran