Exploring Cognitive Decline In Chronic Fatigue Syndrome Through Two-day Cardiopulmonary Testing

PURPOSE: To investigate the effectiveness of a combined cardiopulmonary (VO2) and cognitive testing protocol in identifying post-exertional malaise (PEM) and exercise induced cognitive decline in patients with chronic fatigue syndrome (CFS). Examining the potential of cognitive testing as a complementary tool to capture a broader range of CFS-related impairments. METHODS: 16 subjects (2 male, 14 female) completed a two-day cardiopulmonary exercise test with the addition of cognitive testing before and after exercise on each day. Cognitive testing included the rapid cognitive assessment task (RCAT), trail making test with numbers only (TMTA), trail making test with combination numbers and letters (TMTB) and task switching test (TST). RESULTS: All subjects had significant decreases in cognitive function on day 1 from pre to post exercise (RCAT final score Δ = -139.7 ± 224.9, p = 0.035; TMTA accuracy Δ = -4.4 ± 6.6, p = 0.037, TMTA avg. hit time Δ = -150.8 ± 309.7 ms; TMTB letters avg. time Δ = -487.4 ± 682.3 ms, p = 0.029) and on day 2 from pre to post exercise (RCAT final score Δ = -179.0 ± 52.1, p = 0.028; TMTB accuracy Δ = -3.6 ± 6.9, p = 0.017). In this cohort, 5 subjects qualified as having PEM based on the criteria of ≥10% decrease in peak VO2 and/or ≥ 10% decrease in anaerobic threshold (AT) VO2. The remaining 11 subjects did not have change in exercise performance, however, showed decreases in cognitive performance from pre to post exercise on day 2 (RCAT final score Δ = -183.0 ± 188.9, p = 0.012; RCAT accuracy Δ = -6.33 ± 6.95, p = 0.037; TMTB Min. hit time Δ = -66.4 ± 236.2 ms, p = 0.065; TMTB letters max. time -596.7 ± 2698.2 ms, p = 0.047). CONCLUSION: This study demonstrates the significant cognitive decline following exertion in patients with CFS. These declines are present regardless of whether subjects met the performance requirements for PEM, suggesting that cognitive decline following exertion may be an inherent feature of CFS. These findings support the use of cognitive testing as an assessment tool for patients diagnosed with CFS and provides insight to the cognitive decline that these patients experience post-exertion.