The Relationship between personality and perceived mental fatigability

An increase in number of adults over the age of 65 living in the United States has led to a proportionate increase in the number of individuals reporting symptoms of fatigue - one of the chief complaints among older adults that has been associated with a decline in functionality, and increased risk for negative health outcomes. Perceived mental fatigability is a construct of fatigue that is ideal for the measurement of perceived mental tiredness in an aging population because it accounts for self-pacing bias, provides activities that are standardized in intensity and duration, and can be done with a self-report questionnaire as opposed to a performance-based assessment, which are common among measures of fatigue, but difficult for older adults. Personality traits may be related to perceived mental fatigability through several direct and indirect mechanisms including health behaviors, sensation seeking behaviors, and the cost/benefit theory of motivation. This cross-sectional analysis considers a sample of 1,812 relatively healthy and educated older men from the 4th visit of the Osteoporotic Fractures in Men (MrOS) Study, completed between 2014 and 2016. Linear regression models were used to assess the relationship between optimism, conscientiousness, goal reengagement, goal disengagement, and perceived mental fatigability as measured by the Pittsburgh Fatigability Scale (PFS) when controlling for relevant demographics, psychological and behavioral variables, comorbidities, and physical activity and function. Approximately a quarter of the sample (25%, n=448) reported higher perceived mental fatigability. Goal disengagement was not associated with perceived mental fatigability, and goal reengagement was only significantly associated before the addition of age and demographic variables. Lower conscientiousness and optimism remained significantly associated with higher perceived mental fatigability, independent of all significant covariates. However, depression, self-rated health status, and global sleep quality appeared to have the largest effect on the strength of the relationship. The public health significance of these findings is that the mechanism in which personality traits influence perceived mental fatigability can be used to help design targeted interventions that can reduce perceived mental fatigability in older adults and decrease the prevalence of related adverse health outcomes