Subjective cognitive function in individuals with multiple sclerosis: Associations with objective cognitive function, anxiety, depression, and fatigue.

BACKGROUND

Cognitive impairment is common in persons with multiple sclerosis (pwMS) and is associated with reduced health-related quality of life. Self-report measures are sometimes used to identify cognitive deficits, but the association between subjective and objective cognitive function is unclear.

METHODS

We analyzed data from 345 pwMS who were administered two objective measures of cognitive functioning: Symbol Digit Modalities Test (SDMT), a measure of processing speed, and California Verbal Learning Test-II (CVLT-II), a measure of verbal learning. Participants also completed the computer adaptive testing version of Quality of Life in Neurological Disorders (Neuro-QoL). Subjective cognitive function was assessed using the Neuro-QoL Cognitive Function domain, which measures perceived difficulties with memory, attention, and decision-making. Neuro-QoL Anxiety, Depression, and Fatigue domains were also included in the analysis.

RESULTS

In univariate analyses, subjective cognitive function was associated with SDMT, CVLT-II, Neuro-QoL Anxiety, Neuro-QoL Depression, and Neuro-QoL Fatigue (p < 0.05 for each comparison). Using a multivariable regression model that included SDMT, CVLT-II, Neuro-QoL Anxiety, Neuro-QoL Depression, and Neuro-QoL Fatigue, self-reported cognitive function was not associated with SDMT or CVLT-II. Instead, fatigue had the strongest association with subjective cognitive function in the presence of the other variables. Anxiety and depression were also independent predictors of self-reported cognitive function.

CONCLUSIONS

In pwMS, self-reported cognitive function was more closely associated with anxiety, depression, and fatigue than objective measures of cognitive functioning. These findings suggest that screening for anxiety, depression, and fatigue is important in the clinical interpretation of self-reported cognitive deficits.