Fig. 1

Complex mechanisms associated with aging. Aging is polymorphic and three general forms of aging are described: pathological/problematic, common/usual, and successful aging. Although classically considered to be categorical, these forms of aging can also be seen as a continuum (spectrum of aging; e.g., [59]). The underlying determinants of these different forms of aging are multifactorial and depend on various genetic, environmental, and epigenetic factors (see text for a description). Concerning the “gene–environment correlation” in aging, specific genotypes are more frequently associated with a particular environment and individuals with an advantageous genetic profile seek stimulating environments. Reciprocally, stimulating environments enhance the expression of favorable genetic profiles along with epigenetic mechanisms [136]. These different factors have an impact on the phenotypic profile of individuals and, as concerns the neurocognitive phenotype, at several levels of brain structure and function. More precisely, these modulating factors influence the capacities of neural (cerebral) and cognitive reserves (aging-modulatory reserve factors, AMF). These two forms of interrelated reserves are directly related to behavioral performances such as in lexical access and retrieval, particularly affected in aging