A-14: ADHD, Dementia, or Both? Challenges at the Intersection of Neurodevelopment and Neurodegeneration

Abstract

Objective: Attention-Deficit/Hyperactivity Disorder (ADHD) is associated with functional impairment across the lifespan, as well as comorbidities that may diminish cognitive functioning (e.g., substance use, cardiovascular disease, psychological symptoms). In older adults, these symptoms may complicate accurate detection of dementia. This exploratory case series aims to identify common challenges and opportunities for future research within this population. Method/Data Selection: Four older adults with suspected ADHD (ages 65-81, 50% female) referred due to suspected dementia, with available neurodiagnostic data (including serum biomarkers for Alzheimer’s disease (e.g., Aβ 42/40 ratio, p-tau217, p-tau181)) and various neuroimaging studies (e.g., MRI with NeuroQuant analysis, FDG PET, amyoid PET), were identified via convenience sampling in an outpatient neuropsychology clinic. Collateral informants (family members) were interviewed in all cases. Results/Data Synthesis: In all cases, retrospective symptom history and collateral report were suggestive of ADHD. One participant received formal ADHD diagnosis and treatment in middle adulthood. Patients and informants largely described amplification of longstanding forgetfulness. Cognitive profiles and biomarker data were variable within and across cases. Common comorbidities involved cerebrovascular disease, psychological symptoms, and history of light to heavy alcohol use. Cognitive disorders with multifactorial etiologies were diagnosed in three cases. Conclusions: While findings are limited due to non-systematic sampling and small sample size, this case series provides insights into challenges and opportunities relevant to this population. Lack of data regarding typical trajectories of ADHD symptoms in normal aging, low rates of ADHD treatment in older adults, and comorbidities with known cognitive sequalae complicate accurate detection and staging of underlying dementia, as well as long-term symptom management.