If you have a family member with dementia, you may be wondering if it is hereditary. The answer is yes…and no. The genetics of dementia are complex with many factors weighing in. If your loved one has dementia, the first step in discerning if you are at risk is understanding what caused their dementia in the first place. Although not all dementias can be diagnosed with certainty, a skilled physician can preform a series of medical assessments to provide you with a diagnosis that is as accurate as possible.
Dementia is Not a Disease
Dementia is not a disease rather, a term that describes a wide range of symptoms associated with mental decline and memory loss. Currently, the top two causes of dementia in the U.S. are Alzheimer’s and blockages that restrict vessels from carrying blood and oxygen to the brain resulting in what is called vascular dementia (or multi-infarct dementia). These blockages often cause a series of small strokes that are undetectable to the individual having them. Other hereditary and non hereditary factors can cause dementia, sometimes in combination. Although some forms of dementia cannot be avoided, talk to your doctor about ways you can reduce your chances.
Dementia Caused by Alzheimer’s Disease
It is important to keep in mind that even if you or a family member has a type of dementia that is hereditary, this does not mean that it will inevitably be passed down. In fact, according to the National Institute on Aging, 95% of Alzheimer’s cases develop in older adults and do not have a clear-cut genetic cause. Out of the other approximate 5%, the majority have early-onset Alzheimer’s, which affects people between the ages of 30 and 60 and often has a direct genetic component. Children with one parent carrying a genetic mutation for early-onset Alzheimer’s have a 50/50 chance of developing the disease. This means if your family member did not develop early-onset Alzheimer’s Disease the chances are extremely minimal that it will be inherited by children or grandchildren.
Vascular and Other Forms of Dementia
Somewhere between 60-80% of all dementia cases are related to Alzheimer’s Disease. Another approximate 20% of cases have vascular dementia making it the second most common type. Vascular dementia varies from that found in Alzheimer’s as it is primarily caused by the interruption (infarction) of blood flow to the brain. These infarctions often cause strokes or a series of mini strokes causing widespread brain damage. These are often caused by diseases, health issues and some can be hereditary.
High blood pressure, high cholesterol, and diabetes can all lead to infarctions causing vascular dementia and have genetic components. If you have a close relative with these conditions who also had stroke, it’s likely you could share those risk factors as well. Other common risk factors related to vascular dementia include excessive alcohol, obesity, smoking and a sedentary lifestyle.
Although much less common, diseases such as Huntington’s Disease, Parkinson’s Disease, Pick’s Disease and Creutzfeldt-Jakob Disease may all lead to irreversible dementia. If a family member is diagnosed with a hereditary disease that causes dementia, genetic counseling can help you understand how these genes affect risk, what symptoms to watch for, and what tests and treatments are available.
Reducing the Risk
Although genes can play a part in inheriting dementia, they are only a small piece of the pie. No matter what genes you inherit, regular physical exercise, a healthy diet, limiting alcohol intake and not smoking can reduce your risk at any age.