Adult Attention-Deficit/Hyperactivity Disorder and the Risk of Dementia

Can neurodevelopmental disorders influence the course of neurodegenerative diseases? A scoping review

This scoping review aims at giving an overview of the possible influence of neurodevelopmental disorders (NDDs) on cognitive-behavioral neurodegenerative diseases (CBNDs). Based on the PRISMA-ScR checklist, it details the methods of NDDs screening, the identified NDDs-CBNDs associations, as well as the criteria and types of association. The last literature search was performed in June 2023. In the final study, 32 articles were included. Analysis first showed that NDDs were mainly detected through medical records screening. Second, the association of specific learning disorders and major or mild neurocognitive disorder due to Alzheimer's disease was the most investigated. Third, associations were mostly based on prevalence comparisons. Finally, 66 % of studies reported a positive association between NDDs and CBNDs. Notably, up to 67 % of positive associations were observed with atypical forms of certain CBNDs. Authors' interpretations suggest that NDDs could constitute a risk factor for CBNDs. However, the influence of NDDs on CBNDs still lacks evidence and biological support, possibly due to the heterogeneity of methods and criteria employed. Developing validated assessment tools for all NDDs and conducting cohort studies could be beneficial for research, and clinical practice. Indeed, this review also underlines the importance of adopting a life-span approach regarding CBNDs.

Psychiatric Disease as a Potential Risk Factor for Dementia: A Narrative Review

Neurodegenerative disease is a major global health problem with 150 million people predicted to have dementia by 2050. Genetic factors, environmental factors, demographics, and some diseases have been associated with dementia. In addition to associations between diseases such as hypertension and cerebrovascular disease and dementia, emerging findings associate some psychiatric disorders with incident dementia. Because of the high and increasing global prevalence of dementia and the high worldwide prevalence of psychiatric disorders, the primary objective of this narrative review was to evaluate published findings that evaluate the association between bipolar disorder, depression, anxiety, post-traumatic stress disorder, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorder, schizophrenia and other psychosis syndromes, and personality disorders and personality traits and incident dementia. Here, we highlight findings indicating possible associations between these psychiatric disorders and subsequent dementia and suggest that some psychiatric disorders may be risk factors for incident dementia. Further research, including more large longitudinal studies and additional meta-analyses, however, is needed to better characterize the associations between psychiatric disorders and incident dementia, to identify possible mechanisms for these putative associations, and to identify risk factors within psychiatric disorders that predispose some people with a psychiatric disorder but not others to subsequent dementia. Additional important questions concern how the treatment of psychiatric disorders might affect the risk of incident dementia.

Adult Attention Deficit-Hyperactivity Disorder is associated with Lewy Body Disease and Cognitive Impairment: A prospective cohort Study With 15-year Follow-Up

OBJECTIVES

Past reports have suggested that attention-deficit/hyperactivity disorder (ADHD) may be a risk factor for Lewy body disease (LBD). To confirm this relationship, we conducted the present study.

DESIGN

A prospective observational cohort study with a follow-up to 15 years.

SETTING

The subjects were recruited from cognitive neurology clinics, where they attended for a cognitive complaint or health check-up.

PARTICIPANTS

Two groups of subjects: ADHD adults and healthy subjects.

MEASUREMENTS

The risk of dementia and LBD was estimated with Kaplan-Meier analysis comparing for the presence or absence of ADHD with the log-rank test. Predictors of conversion were assessed through separate univariate and multivariate Cox regression analyses, adjusting for several variables.

RESULTS

The baseline sample consisted of 161 subjects with ADHD and 109 without ADHD. At the end of the follow-up, 31 subjects developed dementia, 27 cases in the ADHD group and 4 in comparison group. Dementia with Lewy bodies (DLB) was the most frequent type (N:20) of which 19 corresponded to the ADHD group. The incidence of non-amnestic-MCI in the ADHD group was higher representing 67.1 % of these subjects (N:108), and 17.4% (N:19) of healthy cases. The hazard ratios for dementia and LBD in the multivariate adjusted model were 3.33 (95% CI 1.0915 to 10.1699) and 54.54 (95% CI 7.4849 to 397.5028), respectively in the ADHD group.

CONCLUSIONS

This study showed that adult ADHD is independently associated with an increased risk of LBD, dementia, and na-MCI. Future studies should clarify this relationship to develop preventive measures for these patients.