2. Genes

Certain genes that can be inherited from a parent can increase a person’s risk of developing dementia. According to experts, there are two types of these genes: risk genes and familial genes.

Risk genes are much more common than familial ones. However, they don’t always end up causing dementia. Until now, there have been more than 20 risk genes that we know can contribute to dementia, although most of them only slightly increase the risk.

The most important risk gene here is called apolipoprotein E (APOE). What’s worrying about this risk gene is that certain variants of it can make a person up to four times more likely to have Alzheimer’s disease than those who don’t have this version of the gene.

However, having the APOE gene doesn’t always mean that you’ll develop dementia. Most people who have it never develop the condition.

Familial genes, on the other hand, are known to significantly increase your risk of developing mental disorders. This is especially true if one of your parents struggled with it. Here’s how this happens: If one parent carries a familial gene, their kid has a 1 in 2 chance of inheriting it. If this happens, the child has a high chance of developing dementia—generally when they are in their 50s and 60s.

This type of gene is rarely associated with mental disorders; however, it may be the cause of about 1 in 3 cases of frontotemporal dementia, which is a less common sort of mental disorder.