As the fastest-growing segment of the planet’s population is the ‘older than 85’ group, the impact is a fast-increasing incidence of dementia resulting from Alzheimer’s and other neurodegenerative diseases (World Health Organization, 2012). Understanding the genetic, biological and environmental determinants of the cascade of events that trigger a neurodegenerative HKI272 disease is thus a priority, but another priority is to understand how the brain reacts functionally to changes occurring in its structural aspects, which can be the result of normal aging or

the incoming of a neurodegenerative disease. This reaction of the brain is at the basis of its attempts to compensate for cognitive impairments that would otherwise result from changes in its structural aspects. In seeking to determine how the brain reacts to Crenolanib cell line and can compensate for cognitive disorders in aging, it is crucial to understand how it handles normal aging. The goal of this review is to report on a number of studies suggesting that the brains of individuals who

maintain adequate cognitive abilities despite neurobiological aging are able to do so because they constantly adapt to changes occurring in the structural brain. After a summary of the impact of aging on brain structures, and a brief reminder of the different functional reorganization principles that are thought to permit the preservation of cognitive abilities, we will summarize some of the studies by our research group that shed light on the dynamic nature of these compensatory mechanisms and their dependence on multiple determinants, including the nature of the task and its complexity. The composition of the brain is affected by the passing of the years. Numerous structural changes Anacetrapib occur, including loss of white matter

structural integrity (Caserta et al., 2009). It is estimated that between 1% and 2% of brain mass is lost each year in adulthood. This loss of brain mass is not equally distributed (Raz et al., 2005). Some areas, in particular the hippocampus, lose brain mass more rapidly than others, such as the lateral prefrontal cortex. In some cases, such as the primary visual cortex, the mass is quasi-stable (Hedden & Gabrieli, 2004). At the same time, some basic cognitive abilities are affected. Information processing speed, attentional processes and inhibition controls are gradually affected (Salthouse, 1996, 2004). Not surprisingly, and despite the fact that cognitive impairment in aging is not the same in all individuals (Valdois et al., 1990), most cognitive abilities, such as spatial orientation and numerical abilities, are affected in normal aging (Schaie & Willis, 1993). Language abilities remain surprisingly well preserved with age, even though the brain regions on which they rely do undergo structural changes as well and they also require many of the basic cognitive abilities known to be affected with age.