Modeling age using cognitive, psychosocial and physiological variables: the Boston Normative Aging Study.

A structural equation model is computed for 36 variables from eight domains of data using 100 healthy male subjects whose age varies between 30 and 80 years. Chronological age is required to be an exogenous variable while cognitive function variables are required to be an ultimate endogenous or outcome set. The model suggests that the direct effect of age on cognition is substantially reduced when social, life style, physiological, and brain state variables are allowed to become intervening variables. The study also finds that there is an association between cognitive function and psychosocial measures relating to general psychiatric symptomatology and social support systems.