Attention-deficit/hyperactivity disorder (ADHD) in adults is independently associated with an increased risk for dementia with Lewy bodies (DLB), dementia, and nonamnestic mild cognitive impairment (naMCI), results of a new study showed.
“Determining whether there is an association between ADHD and subsequent conversion to a specific type of dementia is important. This information could generate opportunities for prevention and early treatment, as well as initiate research into the pathophysiological processes involved in understanding the process of cognitive decline,” the researchers, led by Ángel Golimstok, MD, of Hospital Italiano, Buenos Aires, Argentina, wrote.
The findings were published online on April 10 in The American Journal of Geriatric Psychiatry.
Seeking Confirmation
The researchers first identified a link between DLB and ADHD in 2011. Since then, there have been eight additional studies from other groups also showing a possible link between ADHD and DLB.
To confirm the relationship, the researchers recruited 270 individuals between the ages of 45 and 70 years between 2007 and 2012. Of these, 161 had ADHD, and 109 were healthy controls.
Participants with ADHD met the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, text revision criteria for a diagnosis in the past and had a chronic course of ADHD symptoms from adolescence to adulthood that caused mild to severe impairment.
Investigators excluded participants who had been taking ADHD medications for 6 months or more, those with MCI at study initiation, and those with other comorbid psychiatric disorders.
At baseline, all participants received a physical exam, an MRI, and a neuropsychological exam to test for any type of dementia-related impairment.
Study participants were followed for an average of 12 years. A total of 27 individuals with ADHD developed dementia vs four patients in the control group (17% vs 4%, respectively), and 19 of those also had DLB (P = .002 for both).
Of those who developed any type of dementia, 87% were from the ADHD group. The most frequent type of dementia was DLB, 95% of which occurred in the ADHD group. Overall, DLB represented 70% of the dementia cases among participants with ADHD.
A total of 108 participants with ADHD were subsequently diagnosed with naMCI vs 19 healthy controls (67% vs 17%; P < .001).
“Although this pattern of deficits is reasonably expected in early DLB, these results should be interpreted with caution because they may be related to the overlap of symptoms and cognitive deficits between ADHD and naMCI, which may lead to an overestimation of the degenerative phenomenon. Thus, our cases of naMCI could correspond to the natural aging of ADHD patients and not to pathological deterioration,” the authors wrote.
The researchers pointed out that the sample of patients with ADHD originally sought evaluation because of a cognitive complaint or their own motivation. Therefore, the study results are not generalizable to all patients with ADHD. Another limitation was the relatively small number of patients included in the sample.
There was no reported source of funding, and there were no relevant disclosures reported.
