Cardiovascular Disease and Alzheimer's Disease Risk
Numerous risk factors for cardiovascular disease also appear to be risk factors for Alzheimer's disease. These include:
- elevated LDL cholesterol levels
- low HDL cholesterol levels
- high blood pressure
- overconsumption of unhealthy fats
- excess body weight
- diabetes (now considered to be a cardiovascular risk factor equivalent)
Down Syndrome and Alzheimer's Disease Risk
The risk of Alzheimer's disease is three to five times higher among people with Down syndrome than in the general population. The genetic abnormality responsible for Down syndrome is located on chromosome 21, the chromosome containing the amyloid precursor gene.
Head Injury and Alzheimer's Disease Risk
There appears to be a strong link between serious head injury and risk of developing Alzheimer's disease later in life. Indeed, the risk may be 50% higher in those with a head injury that led to even brief unconsciousness. Because of this, doctors recommend always wearing a seat belt in moving vehicles and a helmet while bicycling to protect the brain from injury.
Depression and Alzheimer's Disease Risk
Several studies have suggested that experiencing depression may increase a person’s susceptibility to Alzheimer's disease later in life. Two studies reported in the Archives of General Psychiatry found an association between depression and the development of Alzheimer's disease.
In one, researchers analyzed the results of several well-conducted studies and found that a history of depression doubled a person's risk of developing Alzheimer's disease. The other study explored the possible link between depression and the formation of beta-amyloid plaques and neurofibrillary tangles (the hallmark brain abnormalities found in Alzheimer's disease).
The researchers examined the brains of 102 people who had died of Alzheimer's disease—50 had a lifetime history of depression and 52 had no history of depression. They found that brains from people who had suffered from depression had more plaques and tangles in the hippocampus than did the brains from people without a history of depression.
Moreover, when the researchers reviewed the medical records of the Alzheimer's patients, they discovered that cognitive decline was more rapid in those with a history of depression. It is not clear whether treating depression can reduce the risk of developing Alzheimer's.