We found a preventive effect (fewer behavioral symptoms at 4 months for TAP-VA participants than controls), a maintenance effect (TAP-VA caregivers provided assistance with a similar number of ADLs at 4 months whereas controls reported increases in assistance required), reductions in frequency by severity of behaviors and pain, and slowing of functional dependence. TAP-VA also benefited caregivers by reducing distress with behavior.Results are consistent with those of other TAP trials (initial pilot, TAP-hospital, TAP Brazil, TAP-Australia), extending reported benefits to pain and functional dependence. It is disappointing that 4-month benefits did not endure to 8 months, yet expectations for long-term effects may be unrealistic without repeated exposure to the treatment (activity engagement). Unlike pharmacotherapies, activity use depends upon caregivers. We could not determine whether caregivers discontinued activity use or activities needed modifications. Why do customized activities reduce behavioral symptoms, improve function, and decrease pain? The etiology of symptoms is unclear. Conceptual models suggest that symptoms are consequences of heightened vulnerabilities to physical and social environments due to neurodegenerative processes. Customized activities may help veterans remain physically active, reducing pain, and meaningfully engaged with purpose, an enduring need. Instructing caregivers in ways to support function may reduce dependency. Future research should identify the underlying mechanisms by which tailored activities have their effects, including neurobiological links. Activities may affect gene expression networks and cellular health, physiological stress, and circadian rhythms, which are potential pathways as to how activity engagement may have its effects.