22 Head Injury and Executive Functioning in the MIDUS Cohort

Abstract

Objective:It has been well established that sustaining a head injury can result in cognitive impairments, but there is little research on the impact of head injuries within middle-aged and older adult samples. Given the two most common samples for head trauma research are athletes and military service members, most of this literature presents findings of individuals under 35 years old. It is important to study head injury outcomes in older samples because greater lengths of time may have passed since the injuries occurred, which may influence findings. Additionally, research indicates that head injuries can lead to measurable executive functioning difficulties - a cognitive domain previously established as susceptible to cognitive ageing-related decline. Therefore, the current investigation seeks to assess the connection between history of head injury and executive functioning performance in middle-aged and older adult participants.Participants and Methods:The current study examined 1150 participants from the 2nd wave of the Midlife in the United States cohort (MIDUS) and 801 participants of the MIDUS refresher panel. As a part of the biomarkers study, participants indicated how many head injuries they experienced (up to three) along with whether they were hospitalized and the year the injury occurred. As a part of the cognitive study, participants completed a battery of measures that were combined into a single Z-scored executive functioning measure. Regression was used to evaluate the association between self-reported head trauma and executive functioning, controlling for age and gender. Post hoc analyses examined hospitalization and recency of head injury.Results:Of the 1951 included participants, 70.7% reported zero head injuries, 20.8% reported one head injury, 5.8% reported two head injuries, and 2.7% reported at least three head injuries. History of head trauma was not associated with lower levels of executive functioning (F[3,1945]=2.68, p=.38). Furthermore, executive functioning performance was not associated with hospitalization for head injury (b=-.04, p=.31) or recent head injuries (b=-.04, p=.70).Conclusions:The current results do not provide evidence of decreased executive functioning performance linked to history of head injury in middle-aged and older adults. These findings are inconsistent with earlier literature suggesting that executive dysfunction is associated with prior head trauma. It is important to consider, however, that the operationalization of executive functioning as a cognitive domain is controversial and produces significant debate. Therefore, the present results solely indicate a lack of connection between previous head trauma and executive functioning, specifically as assessed by the current definition and measures. The present analyses were limited by the broad inclusion of all head injuries rather than a narrowed scope of specifically concussions or mild traumatic brain injuries. However, the study had the advantage of being adequately powered via a large sample size. The current results suggest that additional research is needed within middle-aged and older adult samples to investigate possible connections between head trauma and executive functioning performance using alternate definitions and assessments.