Concussion linked to elevated risks for ADHD, dementia, Parkinson’s disease

Concussion was associated with an increased risk for being diagnosed with ADHD, mood and anxiety disorders, dementia and Parkinson’s disease later in life, according to a study published in Family Medicine and Community Health.

“Given our findings, physicians may wish to follow up with previously concussed patients more thoroughly if they are demonstrating objective signs of the conditions discussed in our study,” Marc P. Morissette, PhD, research assistant at the Pan Am Clinic Foundation in Winnipeg, Canada, told Healio Primary Care. “However, screening each patient with a previous concussion for the conditions of interest in our study may not yet be warranted, given that causation has yet to be shown”

Morissette and colleagues conducted a retrospective population-based cohort study using medical health data in the province of Manitoba, Canada. Researchers examined data from 1990-1991 to 2014-2014.

They matched patients who experienced a concussion with three controls who did not based on age, sex and geographic location, and compared their outcomes.

A total of 47,481 participants were included in the concussion group, and 139,030 participants without concussion were included in the matched control group.

Morissette and colleagues determined that compared with controls, those who experienced a concussion were 39% more likely to be diagnosed with ADHD (adjusted HR = 1.39; 95% CI, 1.32-1.46) and 72% more likely to be diagnosed with a mood and anxiety disorder (adjusted HR = 1.72; 95% CI, 1.69-1.76).

Participants who experienced a concussion were also 72% more likely to develop dementia (adjusted HR = 1.72; 95% CI, 1.61-1.84), and 57% more likely to develop Parkinson’s disease (adjusted HR = 1.57; 95% CI, 1.41-1.75) compared with those who did not have a concussion.

Researchers found that experiencing multiple concussions did not elevate the risk for developing ADHD. However, they determined that those who experienced two concussions had a 62% greater risk for developing dementia compared with those who only experienced one concussion (HR = 1.62; 95% CI, 1.25-2.10).

Compared with those who had one concussion, participants who experienced more than three concussions had a greater risk for being diagnosed with mood and anxiety disorders (HR = 1.22; 95% CI, 1.01-1.47) and Parkinson’s disease (HR = 3.27; 95% CI 1.63-6.59).

In sensitivity analyses, researchers found similar associations between concussion and risk for mood and anxiety disorders in all age groups. However, they determined that those in younger age groups appeared to have a greater risk for ADHD, while those in older age groups appeared to have a greater risk for developing dementia and Parkinson’s disease.

Morissette explained that further research is needed to establish causality between concussion and these other conditions, and to identify any pathophysiological mechanisms contributing to these associations.

“[We] hope our findings will encourage clinicians to be cognizant of the potential long-term implications of concussion, thereby resulting in more thorough clinical examination at initial presentation, and at future appointments,” he said.