Cognitive Workload During a Sustained Visual Attention Task in Middle-Aged and Older Adults With Persistent Symptoms After a Mild Traumatic Brain Injury

Background Individuals with prolonged symptoms after a mild traumatic brain injury (mTBI) report requiring more effort to complete complex and sustained activities. However, the relationship between cognitive workload and patient-reported symptoms is unclear. Objective To compare the cognitive workload between middle-aged and older adults with persistent symptoms after mTBI and controls during a sustained visual attention task and to examine the relationship between workload and patient-reported symptoms. Methods In this cross-sectional study, 48 adults (24 with persistent symptoms after mTBI (mean age = 54.92 ± 9.1 years) and 24 age-matched controls (mean age = 55.00 ± 8.7 years) completed the Dot Cancellation (DC) test. Outcome measures included performance measured by time to completion and number of errors on the test, objective workload measured by the Index of Cognitive Activity (ICA), subjective workload measured by the National Aeronautics and Space Administration Task Load Index (NASA-TLX), and patient-reported outcomes of symptom severity measured by the Post-Concussion Symptom Scale (PCSS), and mental fatigue measured by the Mental Fatigue Scale (MFS). Results Individuals with mTBI symptoms took longer to complete the DC test ( P = .002) and had higher scores on the NASA-TLX (mTBI = 37.5 [20.4, 50.8] compared to controls 10.4 [5, 27.5], P < .001). No differences in ICA were noted between the groups after accounting for DC time. Moderate correlations were observed between NASA-TLX and PCSS (ρ = .58, P < .001) and NASA-TLX and MFS (ρ = .58, P < .001). Conclusions Individuals with persistent symptoms following mTBI exhibit greater subjective cognitive workload and take longer to complete a sustained visual attention task compared to age-matched controls. However, objective measures of cognitive workload did not differ significantly once task duration was controlled. Perceived cognitive workload experienced by this population is influenced by symptom severity and mental fatigue.