Premorbid cognitive functioning influences differences between self-reported cognitive difficulties and cognitive assessment in multiple sclerosis

Cognitive difficulties are reported in up to 60% of people with MS (pwMS). There is often a discrepancy between self-reported cognitive difficulties and performance on cognitive assessments. Some of this discrepancy can be explained by depression and fatigue. Pre-MS cognitive abilities may be another important variable in explaining differences between self-reported and assessed cognitive abilities. PwMS with high estimated premorbid cognitive functioning (ePCF) may notice cognitive difficulties in daily life whilst performing within the average range on cognitive assessments. We hypothesised that, taking into account depression and fatigue, ePCF would predict (1) differences between self-reported and assessed cognitive abilities and (2) performance on cognitive assessments. We explored whether ePCF predicted (3) self-reported cognitive difficulties. Eighty-seven pwMS completed the Test of Premorbid Functioning (TOPF), the Brief International Cognitive Assessment for MS (BICAMS), self-report measures of cognitive difficulty (MS Neuropsychological Questionnaire; MSNQ), fatigue (MS Fatigue Impact Scale; MFIS) and depression (Hospital Anxiety and Depression Scale; HADS). Results revealed that, taking into account covariates, ePCF predicted (1) differences between self-reported and assessed cognitive abilities, p < .001 (model explained 29.35% of variance), and (2) performance on cognitive assessments, p < .001 (model explained 46.00% of variance), but not (3) self-reported cognitive difficulties, p = .545 (model explained 35.10% of variance). These results provide new and unique insights into predictors of the frequently observed discrepancy between self-reported and assessed cognitive abilities for pwMS. These findings have important implications for clinical practice, including the importance of exploring premorbid factors in self-reported experience of cognitive difficulties.