If dementia has already occurred in the family, many people are unsure: Am I now at a high risk of developing dementia? But are dementias actually hereditary? And what is the risk for relatives of individuals already affected?
Dementia is not dementia
The term dementia encompasses a variety of different diseases with different causes. There are no individual genes or gene combinations that apply equally to all dementia diseases.
The most common form of dementia is Alzheimer's disease. Accounting for about 60 to 80 percent of all dementia cases, Alzheimer's dementia is the most widespread form of dementia. Regarding genetic characteristics in Alzheimer's, a distinction is made between two forms: the hereditary Form of Alzheimer's disease (familial, autosomal dominant inherited variant) and the age-related form (sporadic variant). While the first form is genetically determined, the age-related variant involves only an increased risk of dementia in conjunction with certain genetic factors.
How likely is it to inherit Alzheimer's?
Hereditary familial Alzheimer's disease accounts for only one to five percent of all Alzheimer's cases; the majority of affected individuals (95 to 99 percent) develop the age-related form. Therefore, Alzheimer's is a hereditary disease in only rare cases. This is a circumstance that offers hope. Because the risk for the age-related form can be lowered. Up to 45 percent of the risk for the age-related form is attributable to modifiable risk factors that can be actively influenced through targeted measures. Try here the digiDEM Bavaria Prevention Coach® and learn how to lower your dementia risk.
In the familial form of Alzheimer's, the probability of inheriting the disease is between 50 and 100 percent, depending on the parents' genes. This risk cannot be influenced. Affected individuals often develop the disease before the age of 65, while the age-related form usually appears after the age of 65. The type of symptoms is very similar in both forms; however, the disease typically progresses faster and is more severe in the hereditary form.
Genetic risk also in other forms of dementia
Genetic factors can also play a role in other forms of dementia. For example, up to 50 percent of people with frontotemporal dementia (FTD) have a family history of dementia or other psychiatric disorders. 15 to 28 percent of cases could be directly hereditary. Furthermore, there is evidence that similar genetic risk factors play a role in Lewy body dementia as in Alzheimer's disease. Here you will find detailed information about frontotemporal dementia and About Lewy Body Dementia.
In summary, certain forms of dementia can be hereditary. Learn more about it in our article on the topic Familial Alzheimer's Disease: Rare Gene Mutation as a Cause. However, hereditary forms of dementia represent only a small proportion of all dementia cases. For most forms of dementia, the following applies: A healthy lifestyle positively influences the risk of dementia.
Sources
DGN e. V. & DGPPN e. V. (Eds.) S3 Guideline on Dementias, Version 4.0, 11/28/2023.
