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New Study Finds Link Between ADHD & Alzheimer's Disease

Morgan Chamberlain
Author:
December 8, 2022
Morgan Chamberlain
mbg Supplement Editor
By Morgan Chamberlain
mbg Supplement Editor
Morgan Chamberlain is a supplement editor at mindbodygreen. She graduated from Syracuse University with a Bachelor of Science degree in magazine journalism and a minor in nutrition.
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Image by Lucas Ottone / `
December 8, 2022

Scientists have previously hypothesized that attention-deficit/hyperactivity disorder (ADHD) may be a risk factor for cognitive decline and Alzheimer's disease (AD). However, the lack of studies investigating age-related cognitive decline in individuals with ADHD later in life has prevented a distinct association between ADHD and cognitive decline—until now.

Researchers from the University of Pittsburgh Medical Center (UPMC) have found an association between genetic liability for ADHD and the development of AD pathophysiology1 in a new study published by Molecular Psychiatry today. This groundbreaking study is the first of its kind to establish a scientific correlation between ADHD and cognitive decline.

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Given the ongoing research on adult-onset ADHD, an influx in adult ADHD diagnoses (especially in women) over the past few years, and the fact that the number of people with Alzheimer's disease (i.e., 6.5 million Americans over the age of 65, per the Alzheimer's Association) is expected to grow 95% by 2050, this scientific discovery is critical for advancing the future of cognitive care for individuals with ADHD and AD.

The brain study design.

Researchers analyzed 212 cognitively unimpaired, self-identified white adults ages 55 to 90 from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Participants' ADHD polygenic risk scores (ADHD-PRS) were measured to determine their genetic liability for ADHD. However, none of the participants had a clinical ADHD diagnosis.

A series of cognitive imaging tests and assessments were performed at the baseline of the study (then six months later, one year later, and annually after that) to track cognitive decline and AD pathology.

These tests included:

  • Amyloid-β positron emission tomography (Aβ-PET) scans to detect deposits of Aβ (a key peptide in the pathogenesis of AD) in the brain
  • Levels of phosphorylated tau (p-tau) in cerebrospinal fluid (CSF)—the accumulation of which leads to synaptic impairment and neuronal dysfunction
  • Brain magnetic resonance imaging (MRI) scans to visually inspect gray matter probability maps
  • Clinical and neuropsychological assessments to test cognitive functions—such as logical memory, word recall, executive function, and auditory verbal learning
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Association of ADHD-PRS with cognition and AD biomarkers were tested over the course of six years.

ADHD & cognitive decline.

The study found that higher ADHD-PRS (i.e., a higher genetic liability for ADHD) was associated with decreased cognitive performance and memory over time.

The combination of a high genetic liability to ADHD and brain Aβ deposition was more significant on cognitive deterioration than either factor alone.

In Aβ-positive individuals, higher ADHD-PRS was also associated with increased CSP p-tau levels, reduced gray matter density, and atrophy in the frontal and parietal regions. No significant association was observed between high genetic liability to ADHD and neurodegeneration in Aβ-negative individuals.

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What's next for ADHD & AD research?

Though this research indicates associations between the genetic risk of ADHD to Alzheimer's disease, lead study author and psychiatry resident at UPMC, Douglas Leffa, M.D., Ph.D., says more work is needed to link a confirmed ADHD diagnosis to the risks of Alzheimer's disease.

"We believe the next step will be to measure biomarkers of Alzheimer's pathology in older individuals that were diagnosed with ADHD in childhood. By following these individuals over time, we will be able to confirm the association between ADHD and late-onset Alzheimer's disease, as well as better comprehend the mechanisms behind it," he explains.

Additionally, Leffa points out that studies on the genetic risk of ADHD (including this one) and most of the Alzheimer's literature have been conducted in individuals that self-identify as white. "Future research should definitely focus on recruiting a more diverse population in order to answer how race plays into the genetic association between ADHD and Alzheimer's disease," he says.

How can individuals with ADHD prevent cognitive decline?

As we've seen in the results of this study, genetic liability for ADHD itself does not lead to neurodegeneration. Rather, a high ADHD-PRS puts Aβ-positive (but not Aβ-negative) individuals at a higher risk of cognitive decline.

As such, the advice for taking care of your cognitive well-being as you age is the same for individuals with and without ADHD:

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The takeaway.

Researchers have established a significant association between genetic liability for ADHD and cognitive decline associated with Alzheimer's disease. That said, additional longitudinal studies can help us determine the exact mechanisms of this association and better understand how interventions might impact brain longevity and cognitive well-being in individuals with ADHD throughout their life span and as they age.

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Morgan Chamberlain
Morgan Chamberlain
mbg Supplement Editor

Morgan Chamberlain is a supplement editor at mindbodygreen. She graduated from Syracuse University with a Bachelor of Science degree in magazine journalism and a minor in nutrition. Chamberlain believes in taking small steps to improve your well-being—whether that means eating more plant-based foods, checking in with a therapist weekly, or spending quality time with your closest friends. When she isn’t typing away furiously at her keyboard, you can find her cooking in the kitchen, hanging outside, or doing a vinyasa flow.