Cognitive reserve in stroke and traumatic brain injury patients

Cognitive reserve (CR) is defined as the ability to cope with brain damage due to pre-existing cognitive processes or to the development of new compensatory processes. Existing research on CR is mostly based on the study of neurodegenerative disorders, such as Alzheimer's disease. Recently, however, this construct has also been applied to other neurological conditions, including multiple sclerosis, Parkinson's disease, epilepsy, stroke, and traumatic brain injury. The present review provides an overview of the studies that have investigated the influence of CR on neuropsychological outcome in stroke and traumatic brain injury patients. We performed a selective search on MEDLINE, CINAHL, and Web of Science Core Collection, using specific keywords including "cognitive reserve", "stroke", and "traumatic brain injury". The review is organized as follows: the first section focuses on works investigating the effect of CR on neuropsychological outcomes in post-stroke patients; the second section discusses studies which support the CR theory in traumatic brain injury. This review suggests that the study of CR in adult brain injury is still insufficient. Future research should investigate the role of other variables, like cognitive and social activities, as markers of CR in patients with brain injury, functional brain correlates of CR in brain activity, and the effect of CR on brain injury rehabilitative outcomes.