Alzheimer's Disease Types - OmniMedicalSearch.com

Conditions & Diseases: Brain & Nervous System

Alzheimer's Disease

Types of Alzheimer’s Disease

Alzheimer’s disease is categorized into three types:

1. Early Onset Alzheimer’s:
Less than 10% of those who suffer from Alzheimer’s disease are diagnosed with this rare type which usually affects those 65 and younger. People with Down’s syndrome, often in the age group of mid- to late 40s or early 50s, are at risk of being affected by this type with patients experiencing premature aging.

Brain abnormalities associated with Alzheimer’s disease are observed in younger people affected by this type. “Early onset of Alzheimer's appears to be linked with a genetic defect on chromosome 14, to which late-onset of Alzheimer's is not linked.” A more commonly observed condition in early onset of Alzheimer’s disease is myoclonus or muscle twitching and spasms (6).

Mutations of three genes, namely presenilin 1, presenilin 2, and amyloid precursor protein, are associated with Early Onset Alzheimer’s disease. These genes in isolation do not cause Alzheimer’s, however, mutations of these genes, can cause the disease (7).

Changes in the brains of younger people affected by Alzheimer’s disease are microscopic, involving twisting of nerve cells “known as neurofibrillary tangles” and formation of structures called plaques by a sticky protein called beta amyloid. These plaques and tangles tend to damage healthy brain cells leading to shrinking and atrophy (8).

2. Late Onset Alzheimer’s:
About 90% of Alzheimer’s disease cases pertain to this type. Also called as Sporadic Alzheimer’s, Late Onset Alzheimer's affects people 65 and older. Seniors 85 and older have a 1 in 2 chance of developing this type of AD (7).

3. Familial Alzheimer’s Disease (FAD):
Familial Alzheimer's Disease is a very rare type of Alzheimer's Disease, affecting less than 1% of all AD cases. FAD usually strikes at a younger age to people in their 40s and 50s. This type is genetically inherited due to a fault on chromosomes 1, 14 or 21 (7).

Article by Kona Vishnu, MS
Medical Writer,
OmniMedicalSearch.com