Various research approaches try to solve the puzzles related to dementia or healthy brain ageing. Neurogenetic, neuroimaging and neuropharmacological research are the most visible of these. Psychological research in dementia has been instrumental in improving familial or institutional care. However, it has not been regarded as basic research. Recent psychological research into the mechanisms of co-forming or shaping the clinical presentation of dementias can be counted as truly basic research. The ‘cognitive or brain reserve’ concept has been fruitful in implementing psychological knowledge on plasticity factors in dementia. The new concept of ‘motivational reserve capacity’ extends these psychological concepts. In particular, it provides a basis for integrating various findings on how lifestyle factors effectively shape clinical dementia presentations – or lead to healthy brain ageing.