Intraindividual variability, subjective cognitive difficulties, and head injury history in former collegiate athletes

Objectives: The association between head injury history and subjective cognitive symptoms among contact sport athletes has been frequently reported, but links between head injury history and performance-based measures have been more variable. Dispersion-based intraindividual variability (IIV) may better align with subjective cognitive concerns and be a more sensitive measure of subtle head injury-related changes. This study investigated the associations among IIV, subjective cognitive symptoms, and head injury history. Methods: Former collegiate football players (N = 57 included in analyses; age = 38 ± 1.5 years) completed evaluations consisting of neuropsychological assessment, subjective rating of cognition (Neuro-QoL Cognitive Functioning-Short Form and Behavior Rating Inventory of Executive Function-Adult; BRIEF-A), and structured interviews of head impact history (i.e. HIEE). Three IIV indices were calculated reflecting degree of dispersion across cognitive domains: Memory-IIV, reaction time/processing speed-IIV (RT/PS-IIV), and attention/executive function-IIV. General linear models were fit to test associations among IIV, subjective measures, concussion history, and Head Impact Exposure Estimate (HIEE). Results: Greater history of concussion and RHI exposure were not significantly associated with levels of cognitive dispersion (IIV indices, p's >.05). Worse general subjective cognition was associated with greater RT/PS-IIV, and worse BRIEF-A metacognition was associated with greater memory-IIV, even when controlling for psychological distress and sleep quality. Conclusions: Results support the assessment of dispersion in cognitive performance as a useful objective measure that complements subjective cognitive symptoms. While IIV is clinically relevant for detecting subtle cognitive difficulties not captured by central tendency methods, it may only indirectly, if at all, relate to changes associated specifically with head injury history.