- Recent research has found a link between ADHD and a heightened risk of cognitive decline, which, in turn, is a risk factor for dementia.
- The study also found that individuals who have high genetic risk for ADHD have a heightened dementia risk, as well.
- Longer-term studies are needed to confirm the potential mechanisms behind this striking association.
New research led by scientists from the University of Pittsburgh School of Medicine (UMPC) has found that adults with attention-deficit/hyperactivity disorder (ADHD) have a heightened risk of mild cognitive impairment in later life.
Mild cognitive impairment is characterized by memory issues and a slight decline in thinking skills, and can be a risk factor for developing dementia.
The study findings appear in
Speaking to Medical News TodayDouglas Teixeira Leffa, MD, PhD, co-first author of this study, psychiatry resident at UPMC at the time when this study was conducted, explained what motivated the research team to investigate this association.
“Researchers have been seeing this link for a while, and what this study adds is a stronger look at it,” said Teixeira Leffa.
“We observed this association both when ADHD was defined clinically and when we examined an estimate of genetic liability to ADHD, which provides complementary evidence that the relationship is not simply explained by how ADHD is diagnosed or recorded in healthcare settings,” the study author explained.
35% greater odds of dementia with highest ADHD genetic risk
For this study, the research team analyzed the electronic health records and genomic data of 187,341 adults ages 50 and older from the
In the first instance, the researchers found that 6.7% of participants with ADHD developed cognitive impairment as they got older, while only 3.4% of participants without ADHD experienced the same.
They concluded that people with ADHD had a more than four-fold higher risk of cognitive impairment compared with their neurotypical peers. The increase in risk remained stable even after the researchers accounted for confounding factors including age, biological sex, and comorbidities.
When they calculated participants’ genetic risk score for ADHD, the research team further found that those with the highest genetic risk for this neurodivergent profile had 35% greater odds of developing dementia than those with the lowest genetic risk for ADHD.
Why is ADHD linked to cognitive impairment risk?
The current study did not look at the potential mechanism behind the link between ADHD and cognitive impairment risk but previous research from a different team of scientists may offer some subtle clues.
A study conducted by researchers from the Geneva University Hospitals and the University of Geneva (UNIGE), in Switzerland – which appeared in
The UNIGE researchers assessed the iron content in the brains of 32 adults ages 25–45 with ADHD, and those of 29 age-matched neurotypical peers. The researchers also measured neurofilament light chain protein (NfL) levels in the participants’ blood.
Over-accumulation of iron in the brain is associated with
The UNIGE study found that adults with ADHD presented altered levels of iron accumulation in different regions of the brain compared to their neurotypical peers, as well as increased blood NfL levels.
So far, however, the exact reasons for a higher risk of age-related neurodegeneration in adults with ADHD remain unconfirmed.
“Why individuals with ADHD may be more likely to develop dementia remains a crucial unanswered question,” said Teixeira Leffa.
“One possibility is that ADHD may be associated with lower cognitive reserve or resilience, meaning that people with ADHD may have less ability to compensate for pathological age-related changes in the brain, so symptoms such as memory problems could become noticeable earlier. Another possibility is that people with ADHD are, on average, more exposed over the life course to factors that are themselves associated with poorer cognitive health, including sleep problems, cardiometabolic risk, physical inactivity, substance use, chronic stress, and social adversity.”
—Douglas Teixeira Leffa, MD, PhD
Does ADHD cause cognitive impairment?
Commenting on the University of Pittsburgh School of Medicine study, Thomas MacLaren, BMBS, MRCPsych, consultant psychiatrist at Re:Cognition Health in London, United Kingdom, emphasized that “we need to look beyond ADHD as a condition affecting attention and concentration.”
“It can affect executive function, sleep, emotional regulation, and overall health throughout a person’s life, all of which may shape long-term cognitive well-being,” MacLaren, who was not involved in the research, explained. “Shared genetic factors may also be involved,” he hypothesized.
According to study co-author Teixeira Leffa, ADHD may be linked to cognitive impairment risk due to a multitude of interacting factors.
“The answer likely involves multiple interacting processes,” he told us. “In our analyses, we used statistical methods to account for several potentially relevant factors, but the role of each of these processes is difficult to quantify precisely using a study design such as ours.”
“Disentangling their relative contributions will likely require prospective longitudinal studies with repeated measurements over time,” noted Teixeira Leffa.
Will I develop dementia if I have ADHD?
According to MacLaren, we need to exercise caution and not assume that ADHD itself is necessarily the factor causing the decline in thinking and memory as people age. He told us:
“The study suggests that genetic susceptibility to ADHD could be associated with a greater risk of cognitive impairment later in life. However, we cannot yet say that ADHD directly causes this increased risk. Co-existing conditions, including depression, anxiety, and sleep disorders, may also contribute.”
“Importantly, this does not mean that people with ADHD will inevitably develop dementia,” MacLaren emphasized. “We need to better understand the relationship, but the findings highlight why long-term cognitive health deserves greater attention.”
Teixeira Leffa likewise emphasized “that having ADHD does not mean that someone will develop dementia.”
“Most individuals with ADHD in our study did not develop cognitive impairment, and our findings should not be interpreted as demonstrating that ADHD causes dementia,” he pointed out, adding that “at this point, we also do not have convincing evidence that a specific ADHD treatment prevents later cognitive impairment.”
What can people with ADHD do to mitigate dementia risk?
Teixeira Leffa suggested that people with ADHD who worry about their brain health as they age should focus on following the same advice as everyone else.
“(A)dults with ADHD can focus on the same factors that are important for brain health in the general population, such as regular physical activity, good sleep, management of cardiovascular and metabolic risk factors, avoiding smoking and harmful substance use, and remaining socially and cognitively engaged,” he told us.
MacLaren echoed this advice, also “encourag(ing) people to seek appropriate support for their ADHD and any co-existing conditions.” He explained that “treatment can improve symptoms and daily functioning, although we do not yet know whether ADHD medication reduces future dementia risk.”
“From an ADHD perspective, effectively managing symptoms and associated medical or psychiatric conditions is also important,” Teixeira Leffa added.
Further, “as people with ADHD age, clinicians and patients should also be attentive to meaningful changes in memory or other aspects of cognition rather than automatically attributing new difficulties to longstanding ADHD,” the study author advised.
ADHD and dementia research: Where to next?
“I would like to see long-term studies following people with ADHD into later life to establish how their cognitive health changes over time and what drives the increased risk,” MacLaren told MNT.
“We particularly need to understand whether ADHD severity, genetics, lifestyle factors and co-existing conditions influence outcomes, and whether treatment has any protective effect,” he explained. “Research should also explore how clinicians can distinguish longstanding ADHD symptoms from early signs of cognitive decline.”
“Ultimately, the aim should be to identify opportunities for earlier intervention without causing unnecessary alarm,” said the consultant psychiatrist. “An increased statistical risk is not a prediction of an individual’s future, and better evidence could help us provide more targeted support as people with ADHD age.”
Finally, Teixeira Leffa stressed that “there are certainly many unanswered questions in this area,” and that the research team’s first aim going forward is “to understand why this relationship exists.”
“We need long-term studies that follow people with well-characterized ADHD across adulthood and into older age, ideally with repeated cognitive assessments, biomarkers, and information about treatment and other health and lifestyle factors. This would help determine whether ADHD itself contributes to risk, and whether the association is driven by shared biological or environmental factors.”
—Douglas Teixeira Leffa, MD, PhD
“Another important question is whether ADHD treatment, or better management of associated risk factors, can influence later cognitive outcomes. At this point, we do not have convincing evidence to answer that question,” the study author concluded.
