Cognitive reserve in the recovery and rehabilitation of stroke and traumatic brain injury: A systematic review

Objective: Cognitive reserve (CR) is the brain's ability to cope with changes related to aging and/or disease. Originally introduced to explain individual differences in the clinical manifestations of dementia, CR has recently emerged as a relevant construct in stroke and traumatic brain injury (TBI). This systematic review aims to investigate whether CR could predict post-stroke and TBI clinical recovery and rehabilitation outcomes, and how different variables used to estimate CR (i.e., proxies) are related to the prognosis and effectiveness of rehabilitation in these clinical populations. Method: A search was made in Pubmed, Embase, and PsycInfo for articles published until 12 January 2023, following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) protocol guidelines. Results: 31 studies were included after completing all screening stages. Overall, results show that a higher CR was associated with a better prognosis and a more effective rehabilitation in most of the clinical aspects considered: cognitive functioning, functional, occupational, and socio-emotional abilities, as well as psychiatric and neurological scales. Conclusions: A higher CR seems to be associated with a more favorable prognosis and a better rehabilitation outcome after stroke and TBI. Results suggest that CR should be taken into account in clinical practice to make more accurate predictions about recovery and effectiveness of rehabilitation. However, some inconsistencies suggest the need for further investigations, possibly using multiple proxies for CR.