What causes Alzheimer’s Disease?
Alzheimer’s disease is caused by parts of the brain shrinking (atrophy), which affects the structure and function of particular brain areas.
It’s not known exactly what causes this process to begin. However, in the brains of people with Alzheimer’s disease, scientists have found:
- Amyloid plaques which are found between the dying cells in the brain, from the build up of a protein called beta-amyloid.
- Neurofibrillary tangles within the brain neurons, from a disintegration of another protein, called tau.
- Imbalances in a chemical called acetylcholine.
It’s also common to have a degree of vascular damage in the brain.
These reduce the effectiveness of healthy neurons (nerve cells that carry messages to and from the brain), gradually destroying them.
Over time, this damage spreads to several areas of the brain. The first areas affected are responsible for memories.
Late-onset Alzheimer’s. This is the most common form of the disease, which happens to people age 65 and older.
Early-onset Alzheimer’s. This type happens to people who are younger than age 65. Often, they’re in their 40s or 50s when they’re diagnosed with the disease.
Familial Alzheimer’s disease (FAD). This is a form of Alzheimer’s disease that doctors know for certain is linked to genes.
The symptoms of Alzheimer’s disease get worse as the disease progresses and are categorised into three stages.
Mild or early stage.
In the early stage the main symptom is memory lapses and forgetfulness. Someone may also experience mood swings and speech problems.
Moderate or mid stage.
As the disease progresses, symptoms of moderate or mid stage include:
- Spatial problems, judging distances and getting lost.
- Visual problems or hallucinations.
- Delusions or false memories.
- Obsessive or repetitive behaviour.
- Sleep problems.
- Memory problems with more recent events.
- Language & speech problems (aphasia).
- Mood swings, frustration or depression.
Severe or late stage.
Earlier symptoms may worsen and new ones may develop, including:
- Difficulty swallowing (dysphagia).
- Mobility problems.
- Loss of appetite or weight loss.
- More prone to infection.
- Significant short term and long term memory problems.
- Gradual loss of speech.
- Neglecting personal hygiene.
On average, people with Alzheimer’s disease live for eight to ten years after their symptoms begin.