An intervention for delirium superimposed on dementia based on cognitive reserve theory

Delirium superimposed on dementia (DSD) accelerates the trajectory of functional decline and results in prolonged hospitalization, re-hospitalization, premature nursing home placement, and death. In this article we propose a theory-based intervention for DSD that is derived from the literature on cognitive reserve and neuroplasticity. We begin by defining cognitive reserve, the guiding framework for our hypothesis. We review the pathophysiology and neuropsychology of delirium noting the similarities with dementia - these two conditions reflecting acute and chronic reductions in cognitive reserve, respectively. We then review the evidence for activity-dependent plasticity as a possible mechanism for sparing cognitive reserve in dementia and its potential for addressing DSD. Cognitive training (CT) in the form of stimulating activities has been shown to evoke cognitive processing and facilitate plasticity in dementia. Because of the similarities between dementia and delirium, the use of recreational activities as a vehicle for supporting attentional capacity, and delivering cognitive stimulation, may hold promise for the resolution of DSD. Based on integrated evidence from the literature, we hypothesize that engagement in cognitively stimulating recreational activities will help reduce delirium severity and duration in persons with dementia while providing improved quality of life and reduced costs of care.