Abstract: Deficits in memory performance have been linked to a wide range of neurological and

neuropsychiatric conditions. While many studies have assessed the memory impacts of individual

conditions, this study considers a broader perspective by evaluating how memory recall is

differentially associated with nine common neuropsychiatric conditions using data drawn from

55 international studies, aggregating 15,883 unique participants aged 15–90. The effects of dementia,

mild cognitive impairment, Parkinson’s disease, traumatic brain injury, stroke, depression, attentiondeficit/

hyperactivity disorder (ADHD), schizophrenia, and bipolar disorder on immediate, short-,

and long-delay verbal learning and memory (VLM) scores were estimated relative to matched healthy

individuals. Random forest models identified age, years of education, and site as important VLM

covariates. A Bayesian harmonization approach was used to isolate and remove site effects. Regression

estimated the adjusted association of each clinical group with VLM scores. Memory deficits

were strongly associated with dementia and schizophrenia (p < 0.001), while neither depression

nor ADHD showed consistent associations with VLM scores (p > 0.05). Differences associated with

clinical conditions were larger for longer delayed recall duration items. By comparing VLM across

clinical conditions, this study provides a foundation for enhanced diagnostic precision and offers

new insights into disease management of comorbid disorders.

Keywords: verbal learning; memory; dementia; depression; Parkinson’s disease; schizophrenia;

stroke; traumatic brain injury; bipolar disorder; attention-deficit/hyperactivity disorder