Israeli researchers have followed more than one hundred thousand adults for seventeen years. They were all born between 1933 and 1952 and had not been diagnosed with ADHD or dementia at the start of the study in 2003. In the following years, 730 of them were diagnosed with ADHD. More than 7,700 people developed dementia. There was more overlap between these groups than you might expect by chance. Adults with ADHD had nearly three times the risk of developing dementia compared to adults without ADHD. For example, by age 85, 43% of older adults with ADHD have been diagnosed with dementia, compared to 15% of older adults without ADHD. The researchers took into account other factors that can increase the risk of dementia, such as smoking, depression, cardiovascular disease, and socioeconomic status.
It is not known why ADHD and dementia often go together. Researchers believe that ADHD in adulthood may be a manifestation of a brain process that makes it difficult to compensate for the aging brain. The scientific article says that less cognitive reserve can lead to ADHD processes that in turn reduce compensatory possibilities.
And finally this. The study did not include people who were diagnosed with ADHD as children. The researchers also noted that adults who took ADHD medications were not more likely to develop dementia. But since it was a very small group, they couldn’t draw any firm conclusions from this.
