APOE4-related differences in cortical thickness are modulated by sex in middle age.

Apolipoprotein E (APOE) ε4, the strongest genetic risk for late-onset Alzheimer's disease (AD), confers greater risk in females than males. While APOE4-related modulation of structural brain integrity in AD is well documented, extant literature on sex-APOE interactions has focused on older adults. The understanding of the healthy brain as a part of the normal aging process and as distinct from explicit disease or pathology is essential before comparison can be made with pathological states.

Reversal learning in young and middle-age neurotypicals: Individual difference reaction time considerations.

Reversal learning is frequently used to assess components of executive function that contribute to understanding age-related cognitive differences. Reaction time (RT) is less characterized in the reversal learning literature, perhaps due to the daunting task of analyzing the entire RT distribution, but has been deemed a generally sensitive measure of cognitive aging. The current study extends our prior work to further characterize distributional properties of the reversal RT distribution and to distinguish groups of individuals with fractionated profiles of performance, which may be of clinical importance within the context of cognitive aging.

A distributional and theoretical analysis of reaction time in the reversal task across adulthood.

Reversal learning assesses components of executive function important for understanding cognitive changes with age. Extant reversal learning literature has largely assessed measures of accuracy, but reaction time (RT) has not yet been well characterized, perhaps due to the daunting task of analyzing non-normal RT distributions. The current study contributes to the literature by examining distributional and theoretical aspects of the entire RT distribution in addition to accuracy.