Alzheimer's disease is a chronic progressive disease affecting memory, thinking and human behavior.

It affects mostly elderly and middle-aged people.

Alzheimer's disease is the cause of dementia number 1 in the world.

Doctors are aware of the existence of this disease for many years, but its causes are still not fully understood. It is not known why one person develops Alzheimer's disease, and another person of the same age and lifestyle remains sane. It is also impossible to heal it.

The risk factors for Alzheimer's are as follows:.

- age: after age 65 the probability of dementia increases dramatically.

- Family history: the presence of close relatives with Alzheimer's disease.

- head trauma: serious injuries, even in the distant past, predispose to dementia.

- heart and vascular diseases: hypertension, stroke, atherosclerosis, hypercholesterolemia Genetic component.

Scientists identify two groups of genes associated with Alzheimer's: risk genes and deterministic genes.

The first simply increase the risk of developing the disease, and the second mean that their carrier will necessarily become a victim of Alzheimer's disease.

Risk genes:.

- apolipoprotein E-E4 gene (APOE-e4): 20-25% of carriers of this gene eventually diagnose Alzheimer's disease.

- inherited from both parents, the APOE-e4 gene further increases the risk, as well as predisposes to the early onset of the disease. The alternative gene, APOE-e2, is a natural defense against dementia - it significantly reduces the likelihood of disease.

- a group of genes that regulate communication between nerve cells of the brain and the level of inflammation in the nervous system. Mutations in these genes are associated with Alzheimer's disease in old age and have little effect on the fate of young people, unlike APOE-e4.

Deterministic genes:.

- the beta-amyloid precursor gene (APP).

- presenilin-1 (PS-1) and presenilin-2 (PS-2) gene. All three deterministic genes are responsible for the accumulation in the brain of beta-amyloid - a toxic protein for nerve cells that causes neuronal death and the development of dementia.

Deterministic genes predispose to Alzheimer's disease with an early onset, but the absence of these genes is not at all "insurance" against a serious illness.

In the presence of APP, PS-1 and PS-2 genes speak of family Alzheimer's disease. Symptoms of dementia in such carriers, as a rule, appear in the age of up to 60 years, sometimes even in 30-40 years.

The share of family Alzheimer's disease accounts for only 5% of cases.

Effect of heredity on other types of dementia:.

- Huntington's disease: a dominant mutation in the 4th chromosome leads to progressive dementia and hyperkinesis, the symptoms usually appear after 30 years.

- dementia with Levi bodies, Parkinson's disease are also genetically determined.

Early signs and symptoms of Alzheimer's disease.

Early signs and symptoms may be forgetfulness and memory loss.

Over time, people start to get confused in places, facts and numbers, becoming more and more disoriented, working capacity is deteriorating, independence in everyday affairs is lost.

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