Causes of Alzheimer’s Disease
What causes Alzheimer's disease is unknown, but genetic factors play a role: The disease seems to run in some families and is caused or influenced by several specific gene abnormalities.
One abnormality affects the protein part of certain lipoproteins, which transport cholesterol through the bloodstream.
Symptoms of Alzheimer’s Disease
In Alzheimer's disease, parts of the brain degenerate, destroying nerve cells and reducing the responsiveness of the remaining ones to many of the chemical messengers that transmit signals in the brain (neurotransmitters).
Abnormalities in brain tissue consist of neuritic plaques and neurofibrillary tangles. Such abnormalities develop to some degree in all people as they age but are much more numerous in people with Alzheimer's disease.
The first sign may be forgetting recent events, although sometimes the disease begins with depression, fears, anxiety, decreased emotion, or other personality changes. In the early stages, judgment and abstract thinking may be impaired. Speech patterns may change slightly; the person may use simpler words, use words incorrectly, or be unable to find the appropriate word. An inability to interpret visual cues may make driving a car difficult.
People with Alzheimer's disease may be able to function socially but may behave unusually. For example, they may forget the name of a recent visitor, and their emotions may change unpredictably and rapidly. They may get lost on their way to the shops.
As Alzheimer's disease progresses, people have trouble remembering events in the past. They may require help with eating, dressing, bathing, or going to the toilet. Wandering, agitation, irritability, hostility, and physical aggression are common. All sense of time and place is lost: People with Alzheimer's disease may even get lost on their way to the bathroom at home. Their increasing confusion puts them at risk of falling. Psychoses, with hallucinations, delusions, and paranoia, develop at some point in about half of people with Alzheimer's disease.
Eventually, people with Alzheimer's disease cannot walk or take care of their personal needs. They may be incontinent and unable to swallow, eat, or speak. These changes put them at risk of undernutrition, pneumonia, and bedsores (pressure sores). Memory is completely lost.
Progression is unpredictable. The expected survival from the time the disorder is diagnosed ranges from 2 to 10 years, but usually 3 to 5 years. On average, people with Alzheimer's disease who can no longer walk live no more than 6 months.
