To investigate the relationship between the P300 event-related potential, neuropsychological measures of memory, subjective memory complaints (SMCs), and indicators of psychosocial functioning.

In this cross-sectional study of 79 community-based older adults, aged 60–75 years, participants completed online surveys and in-person neuropsychological and electroencephalogram (EEG) assessments.

Measures included: the Change subscale of the Metamemory in Adulthood Questionnaire, NIH Toolbox Emotions battery (Perceived Stress and Psychological Well-Being), Geriatric Depression Scale, Geriatric Anxiety Scale, electrocortical measures (EEG), California Verbal Learning Test, 3rd Edition, and diagnostic ratings for mild and major neurocognitive disorders based on full neuropsychological battery, clinical interview, and two-clinician consensus.

P300 amplitude was associated with long-delay verbal memory recall and diagnostic rating. SMCs were not associated with objective memory or diagnostic rating. SMCs were associated with higher perceived stress, anxiety, and depression symptoms and lower psychological well-being.

Neural indicators such as the P300 may be useful for early detection of cognitive impairment. SMCs were not a reliable indicator of early memory impairment in relation to neuropsychological or neural indicators, but may be a useful indicator of unreported stress and mood symptoms in clinical settings.