Adults whose parents have dementia are likely to be diagnosed earlier

New research by American researchers at the Washington University School of Medicine in St. Louis indicates that adults whose parents have dementia are likely to develop the same symptoms an average of six years earlier.

The study indicates that factors like education, blood pressure and carrying the APOE4 gene — which increases the risk of dementia — explain less than a third of the variation of the age at which dementia symptoms begin to appear.

“It’s important to know who is going to get dementia, but it’s also important to know when symptoms will develop,” said lead author Gregory Day, MD, an assistant professor of neurology.

“If we can better understand the factors that delay or accelerate the age at onset, we eventually could get to the point where we collect this information at a doctor’s visit, put it through our calculator, and determine an expected age at onset for any adult child of a person with dementia.”

To consider the link between hereditary factors and intergenerational differences in the age at which dementia appears, Dr Day’s team worked with a group of 164 Alzheimer’s patients who had at least one parent affected by the disease.

Alzheimer’s disease is the most common cause of dementia, which affects about 5.8 million people in the United States. Between 10 and 15% of the children of Alzheimer’s patients will themselves develop symptoms of the disease.

Picture; iStock

Diagnosis an average of 13 years earlier when both parents have dementia

The researchers examined medical records and interviewed the participants and their close friends and family members to determine the age at which dementia began to appear in each participant as well as in their parents.

People who had one parent with dementia themselves developed the symptoms an average of six years earlier than the average age their parents were when they were diagnosed. When both parents had dementia, symptoms appeared an average of 13 years earlier in their adult children.

Although the researchers assessed multiple factors including genes, cardiovascular disease and education, they found that these factors did not fully determine the cause of earlier symptom manifestation in the adult children.

“…[P]eople with two parents with dementia developed the disease much younger than people with one parent. That suggests that it’s more than just changes in diagnostic criteria or social attitudes.

“People with two parents with dementia may have a double dose of genetic or other risk factors that pushes them toward a younger age at onset,” explained Dr Day in a statement.

“Although we’re not yet at the point where we can modify people’s genes, we can begin to explore how these genes may accelerate or slow down the onset of dementia in these individuals. By learning more about the effect of these genes on Alzheimer’s disease, we may be able to develop novel treatments.”

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