Background: Research has examined the influence of positive psychological factors including purpose in life (PIL), need for cognition (NFC), and psychological flexibility on behaviors that support brain health (i.e., preserved cognitive functioning and brain structures). However, more research is needed to examine their predictive validity in relation to other important factors in this context including emotional distress and dementia worry. Objective: The current study included 348 older adults who completed self-report measures of PIL, NFC, psychological flexibility, emotional distress, dementia worry, and brain health behavior engagement via Qualtrics. Results: Greater PIL was associated with more engagement in all brain health behaviors while NFC was only associated with more cognitive activity, heart health monitoring, and stress management. Psychological flexibility mediated the association between PIL and engagement. Conclusion: Our findings add evidence to the incremental validity of positive neuropsychological factors on engagement in brain health behaviors. Implications for neuropsychological interventions are discussed.