Risk of neurodegenerative disease or dementia in adults with attention-deficit/hyperactivity disorder: a systematic review.
Level 3 - non-randomized controlled study
Systematic review of observational studies (5 cohort and 2 case-control studies)
PubMed 37663597 · doi:10.3389/fpsyt.2023.1158546
What was done
A systematic review of five databases was conducted in May 2023 to evaluate the association between ADHD and incident neurodegenerative diseases or dementia in cohort, case-control, and clinical trial designs. Study characteristics were extracted by two independent reviewers, and risk of bias was assessed using the Newcastle-Ottawa Scale. From 2,137 initial records, seven studies (five cohort and two case-control) met inclusion criteria, examining all-cause dementia, Alzheimer's disease, Parkinson's and Lewy body diseases, vascular dementia, and mild cognitive impairment. Due to heterogeneity in covariates and reported risk metrics, findings were synthesized narratively without meta-analysis.
What was found
The abstract reports no numerical effect sizes or risk ratios. Four of the seven studies were rated as having an overall low risk of bias. The included studies demonstrated evidence of an association between ADHD and subsequent dementia or neurodegenerative disease, but the magnitude of any direct effect could not be established.
Why it matters
This review collates the emerging observational literature linking ADHD to long-term neurocognitive decline, showing that while a relationship is documented, the field currently lacks sufficiently uniform methodology to quantify risk.
Limits
The total evidence base is small (7 studies), composed entirely of non-randomized observational designs (5 cohort, 2 case-control), with 3 of 7 studies not achieving a low risk of bias rating. Substantial heterogeneity in covariate adjustment and reported risk metrics precluded meta-analysis, and underlying mechanisms or direct causal pathways remain unmeasured.
Cited by
- supports Published scientific research demonstrates a relationship between ADHD and an increased risk of cognitive decline.