[Cognitive reserve: evidence, limitations and future research lines].

This review presents recent research on the mechanisms that cause some individuals with a certain degree of underlying neuropathology to show clinical symptoms of dementia, while others, with the same degree of neuropathology, appear cognitively intact. The mechanisms that explain the cognitive reserve hypothesis are also discussed. We describe the explanatory models that have been developed to defend the cognitive reserve hypothesis, the variables that may be associated with this phenomenon, how cognitive reserve manifests in neuropathological terms, and the methodological limitations of the research developed so far. We highlight how some variables associated with cognitive reserve have progressively acquired greater influence in recent years (work complexity, literacy, bilingualism, cognitive stimulation, etc.), while others have progressively been shown to be less important (brain volume). Likewise, we address the need for longitudinal studies that would clarify the causal directionality between the distinct variables and cognitive reserve.