Risk factors

Some of the risk factors associated with dementia can be managed through lifestyle changes or appropriate medical treatments.

Cardiovascular risk factors

Brain infarcts, heart disease and mid-life hypertension increase the risk of Alzheimer’s disease and Vascular dementia. Smoking has also been identified as a risk factor. 

Diabetes

A recent study found that having diabetes increases the risk of developing Alzheimer’s disease by 65%. This risk can be reduced by careful management of diabetes with medications that maintain blood glucose levels within a healthy range.

High cholesterol

Cholesterol is essential to brain function – it is a component of cell membranes (structures that enclose nerve cells), and it is required for the repair and establishment of new connections between nerve cells. However, studies have shown that, high cholesterol in mid-life and late-life can increase the risk of Alzheimer’s disease. Subsequent studies have indicated that cholesterol lowering drugs may lower the risk of developing Alzheimer’s disease.

High homocysteine levels

Homocysteine is a by-product of many metabolic reactions occurring in our body. Some studies have found that high homocysteine levels are associated with an increased risk of Alzheimer’s disease and other dementias. Adequate intake of vitamin B and folate can help reduce homocysteine levels.

Some risk factors predisposing to dementia are associated with genetic inheritance or previous life events, for example:

Genes associated with Alzheimer’s disease

One gene (Apolipoprotein E) has been associated with an increased risk of late onset Alzheimer’s disease while three additional genes (Amyloid Precursor Protein, Presenilin 1 and Presenilin 2) are associated with early onset Alzheimer’s disease. 

Apolipoprotein E (ApoE) carries and delivers cholesterol to the nerve cells which use it for the repair and establishment of new connections. There are three common variants of the ApoE gene. The ApoE 3 variant is the most common, the ApoE 4 variant is thought to increase the risk of Alzheimer’s disease while the ApoE 2 variant appears to have a protective influence.

Mutations in the Amyloid Precursor Protein (APP), Presenilin 1 and Presenilin 2 cause the inherited form of Alzhaimer's disease. However, a majority Alzheimer’s disease cases appear to be sporadic and only a small number of cases are known to be inherited. 

The APP gene makes a protein that is present on the surface of nerve cells and may help them grow and move. The presenilin 1 and 2 genes make proteins that are required for the correct functioning of the APP protein. Mutations in any one of these genes can cause the APP protein to be cut off from the surface of nerve cells. When this happens APP tends to accumulate in amyloid plaques which are a hallmark of Alzheimer’s disease.

Family history

A family history of dementia increases one’s risk of developing dementia. This is probably due to genetic factors that have not yet been discovered.

Head injury

A study of World War II veterans indicated that moderate to severe head injury increased risk of developing Alzheimer’s disease and other dementias. Another study found that this risk is further increased if the head injury resulted in loss of consciousness.