In a new study from Karolinska Institutet, researchers found a link between ADHD and dementia across generations.
They found that parents and grandparents of individuals with ADHD were at higher risk of dementia than those with children and grandchildren without ADHD.
The findings suggest that there are common genetic and/or environmental contributions to the association between ADHD and dementia.
ADHD (attention-deficit/hyperactivity disorder) is a neurodevelopmental disorder characterized by inattention, impulsiveness and hyperactivity. It affects an estimated 3 percent of adults worldwide.
The number of new ADHD diagnoses has increased dramatically in the last decades amid increasing awareness and knowledge about the disorder.
However, since the diagnosis is still relatively new, there has only been a limited number of small studies on the development of dementia in people with ADHD, often with conflicting results.
In the study, the researchers wanted to overcome this by examining to what extent older generations of individuals with ADHD were diagnosed with dementia.
They looked at more than two million people born in Sweden between 1980 and 2001, of whom around 3.2% were diagnosed with ADHD.
Using national registries, the researchers linked these persons to over five million biological relatives, including parents, grandparents and uncles and aunts, and investigated to what extent these relatives developed dementia.
The team found that parents of individuals with ADHD had a 34% higher risk of dementia than parents of individuals without ADHD.
The risk of Alzheimer’s disease, the most common type of dementia, was 55% higher in parents of individuals with ADHD. Individuals with ADHD were more likely to have parents with early-onset dementia than late-onset.
The researchers note that the absolute risk of dementia was low for the parent cohort; only 0.17% of the parents were diagnosed with dementia during the follow-up period.
The association was lower for second-degree relatives of individuals with ADHD, i.e. grandparents and uncles and aunts.
For example, grandparents of individuals with ADHD had a 10% increased risk of dementia compared to grandparents of individuals without ADHD.
While the study is unable to determine a cause-and-effect relationship, the researchers present several potential explanations that can be explored in future research.
One is that there are undiscovered genetic variants that contribute to both traits, or family-wide environmental risk factors, such as socioeconomic status, that may have an impact on the association
Another possible explanation is that ADHD increases the risk of physical health conditions, which in turn leads to an increased risk of dementia.
For more information about dementia and your health, please see recent studies about this blood test can predict dementia, Alzheimer’s 5 years early and results showing that Mediterranean diet may strongly prevent dementia, memory loss.
The study is published in Alzheimer’s & Dementia. One author of the study is Le Zhang.
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