ORIGINAL PAPER Structural and Functional Imaging Correlates of Cognitive and Brain Reserve Hypotheses in Healthy and Pathological Aging David Bartre ´s-Faz • Eider M. Arenaza-Urquijo Received: 22 December 2010 / Accepted: 25 July 2011 Ó Springer Science+Business Media, LLC 2011 Abstract In the field of ageing and dementia, brain- or cognitive reserve refers to the capacity of the brain to manage pathology or age-related changes thereby mini- mizing clinical manifestations. The brain reserve capacity (BRC) hypothesis argues that this capacity derives from an individual’s unique neural profile (e.g., cell count, synaptic connections, brain volume, etc.). Complimentarily, the cognitive reserve (CR) hypothesis emphasizes inter-indi- vidual differences in the effective recruitment of neural networks and cognitive processes to compensate for age- related effects or pathology. Despite an abundance of research, there is scarce literature attempting to synthesize the BRC the CR models. In this paper, we will review important aging and dementia studies using structural and functional neuroimaging techniques to investigate and attempt to assimilate both reserve hypotheses. The possi- bility to conceptualize reserve as reflecting indexes of brain plasticity will be proposed and novel data suggesting an intimate and complex correspondence between active and passive components of reserve will be presented. Keywords Aging Á Dementia Á Brain reserve Á Cognitive reserve Á Neuroplasticity Á MRI Á Functional MRI Á Cognition Á Brain networks Á Compensation Introduction Cognitive and Brain Reserve Cognitive- or brain reserve refers to the hypothesized capacity of an adult brain to cope with brain pathology in order to minimize symptomatology (Stern 2002). Within the fields of ageing and dementia, the concept of reserve emerged from repeated observations of Alzheimer’s Dis- ease (AD) neuropathology in otherwise clinically healthy elders (Snowdon 2003) and by reported weak or absent associations between unique cognitive profiles and AD neuropathology (Driscoll et al. 2006). Two influential hypotheses have been proposed to account for these counterintuitive observations (Stern 2002). The first is the ‘brain reserve capacity’ (BRC) model. Largely concerned with anatomical correlates, the BRC suggests that passive factors (such as the number of synapses or brain volume) confer a particular capacity to endure neuropathological processes. With regards to dementia and pre-dementia conditions, the BRC serves to prolong the preclinical stage until a critical threshold is reached. Once the BRC is depleted by increasing levels of neuropathology, vulnera- bility to brain damage is unavoidable and, eventually, clinical and functional deficits become evident (Satz et al. 1993). This hypothesis predicts that individual differences in anatomy manifest in different levels of insult tolerance before clinical deficit emerges. A proposed shortcoming of the passive (BRC) model is that it does not account for individual differences in This is one of several papers published together in Brain Topography on the ‘‘Special Issue: Brain Imaging across the Lifespan’’. D. Bartre ´s-Faz (&) Á E. M. Arenaza-Urquijo Department of Psychiatry and Clinical Psychobiology, Faculty of Medicine, University of Barcelona, Casanova 143, 08036 Barcelona, Spain e-mail: dbartres@ub.edu D. Bartre ´s-Faz Institut d’Investigacions Biome `diques August Pi i Sunyer (IDIBAPS), Barcelona, Spain 123 Brain Topogr DOI 10.1007/s10548-011-0195-9