Relationships between intraindividual cognitive variability, self-reported cognitive dysfunction, and functional...

Intraindividual cognitive variability (IIV) may be associated with subtle cognitive difficulties and potentially be an early indicator of decline. This study aimed to examine the relationships between IIV, self-reported cognitive difficulties, and functional difficulties in persons with multiple sclerosis (pwMS).

Three measures of IIV, intraindividual standard deviation (ISD), maximum discrepancy score (MDS), and coefficient of variance (CoV), and 1 mean composite were created from 11 neuropsychological indices. Participants (n = 35) completed the Perceived Deficits Questionnaire (PDQ), Test of Everyday Cognitive Abilities (TECA), and a questionnaire about whether they experienced memory-related problems in eight functional areas. Partial Spearman correlations examined the associations between cognitive performance, PDQ, TECA, and number of self-reported functional memory problems, controlling for premorbid functioning (Test of Premorbid Functioning; TOPF) or a composite of fatigue, depression, and anxiety symptom ratings (SymptoMScreen) in separate matrices.

In both matrices, the number of self-reported functional memory problems was correlated with the PDQ (ρ = .39-.47) and ISD (ρ = -.38), as well as CoV in the SymptoMScreen matrix (ρ = -.31). PDQ was correlated with both MDS (ρ = -.33) and ISD (ρ = -.33) only when controlling for SymptoMScreen. In both matrices, TECA was correlated with CoV (ρ = .46-.50) and mean performance (ρ = -.66 to -.68), as well as ISD when controlling for TOPF (ρ = .31).

The number of self-reported functional memory problems was associated with worse ratings of perceived cognition (i.e. PDQ). Increased dispersion on different metrics, but not mean performance, was associated with fewer reported functional memory problems and self-reported cognitive dysfunction, when controlling for premorbid functioning or symptoms. Both IIV metrics and mean performance were related to greater difficulty completing timed everyday activities. Results suggest a disconnect between pwMS's perceptions of their functional difficulties with an objective measurement of their abilities. Further evaluation into IIV is needed to help guide earlier identification and intervention of cognitive problems in pwMS.