The relationship between cognitive complaints and burden of non-cognitive symptoms in multiple sclerosis

Cognitive complaints are common in multiple sclerosis, but their relationship to non-cognitive symptoms such as fatigue, sleep dysfunction and psychopathology has not been systematically examined in patients referred for specialist cognitive evaluation. These potentially modifiable symptoms may warrant attention in a clinical context.

This study aimed to characterise common patterns of cognitive and non-cognitive symptoms in a referred patient cohort and determine whether cognitive complaints are associated with clinically significant fatigue, sleep dysfunction and psychopathology.

Cognitive complaints were captured using (a) a binary classification derived from clinical impression and (b) a severity rating from a self-report instrument. Objective cognitive performance was measured across five cognitive domains. Patients also completed self-report measures of fatigue, sleep dysfunction and psychopathology.

Fifty-one patients were included. Although 98% had cognitive complaints, only 29% had objective cognitive impairment. Most (90%) had significant non-cognitive symptoms, primarily fatigue (86%), sleep dysfunction (28%) and depression (26%). Pattern analysis revealed that the most common symptom phenotype was cognitive complaints with significant non-cognitive symptoms, occurring in the absence of objective cognitive impairment. More severe cognitive complaints were associated with greater psychopathology (r = 0.57, BF₁₀ = 2188.48), fatigue (r = 0.53, BF₁₀ = 366.44) and sleep dysfunction (r = 0.47, BF₁₀ = 69.27).

Cognitive complaints in multiple sclerosis may reflect broader non-cognitive symptom burden rather than objective cognitive impairment, even among patients referred for specialist evaluation. Their presence should prompt consideration of fatigue, sleep disturbance and psychopathology as potential targets for intervention.