Hormones as “difference makers” in cognitive and socioemotional aging processes

Abstract

Aging is associated with well-recognized alterations in brain function, some of which are reflected in cognitive decline. While less appreciated, there is also considerable evidence of socioemotional changes later in life, some of which are beneficial. In this review, we examine age-related changes and individual differences in four neuroendocrine systems—cortisol, estrogen, testosterone, and oxytocin—as “difference makers” in these processes. This suite of interrelated hormonal systems actively coordinates regulatory processes in brain and behavior throughout development, and their level and function fluctuate during the aging process. Despite these facts, their specific impact in cognitive and socioemotional aging has received relatively limited study. It is known that chronically elevated levels of the stress hormone cortisol exert neurotoxic effects on the aging brain with negative impacts on cognition and socioemotional functioning. In contrast, the sex hormones estrogen and testosterone appear to have neuroprotective effects in cognitive aging, but may decrease prosociality. Higher levels of the neuropeptide oxytocin benefit socioemotional functioning, but little is known about the effects of oxytocin on cognition or about age-related changes in the oxytocin system. In this paper, we will review the role of these hormones in the context of cognitive and socioemotional aging. In particular, we address the aforementioned gap in the literature by: (1) examining both singular actions and interrelations of these four hormonal systems; (2) exploring their correlations and causal relationships with aspects of cognitive and socioemotional aging; and (3) considering multilevel internal and external influences on these hormone systems within the framework of explanatory pluralism. We conclude with a discussion of promising future research directions.

Patterns of Behaviour, Group Structure and Reproductive Status Predict Levels of Glucocorticoid Metabolites in Zoo-Housed Ring-Tailed Lemurs, Lemur catta

“…Cortisol titres change across age in some primate species potentially confounding experimental results evaluating HPA function [Ebner et al, 2015]. We predict (P2) a positive correlation between cortisol levels and age as shown in other primate species (e.g.…”

Sexual dimorphisms in swimming behavior, cerebral metabolic activity and adrenoceptors in adult zebrafish (Danio rerio)

“…Such paradigms of dimorphic behavioral phenotypes characterize exploratory behavior [19], aging process [20], early life stress influences [21], anxiety-like and social behavior [22,23]. The latter behavioral dimorphisms are linked to the noradrenergic system, as it is a critical mediator of acute stress-induced anxiety [24], of sympathetic stress responses, locomotion and cognition [25,26].…”

Oxytocin’s effect on resting-state functional connectivity varies by age and sex

“…This emerging evidence of age and sex differences in the actions of the oxytocin system raise the possibility of a regulation of oxytocin's effects by gonadal steroids (e.g., testosterone, estrogen, progesterone) or other age- and sex-specific biological factors (e.g., brain anatomy, endogenous oxytocin levels; Bos et al, 2012; Carter et al, 2007; Ebner et al, 2015b; Kanat et al, 2014; MacDonald, 2013), as proposed in our recent Age-Related Genetic, Neurobiological, Sociobehavioral Model of Oxytocin (AGeNeS-OT) model (Ebner et al, 2013). Further, evidence that oxytocin's social-cognitive and affective effects differ by level of proficiency, in that more impaired compared to less impaired individuals appear to benefit more from oxytocin administration (Bartz et al, 2010) also supports the idea that oxytocin's effects may vary across age and sex.…”