AIM: To explore the need for a personal measure of cognitive decline (Personal Cognitive Decline, Personal-CD), in individuals with Pediatric Onset Multiple Sclerosis (POMS), focusing on declines relative to estimated previous abilities rather than the normative standards. We explored the significance of both Personal-CD, defined as a decline in cognitive performance relative to individual's estimated premorbid abilities, as well as Cognitive Impairment (CI), defined as performance below -1.5 SD of the normative means. METHOD: A cohort observational study included 31 POMS patients (20 females, mean age 15.8 years) recruited from a pediatric neuroimmunology clinic, with a 94 % consent rate. Participants underwent neuropsychological assessments across six cognitive domains and psychological questionnaires on anxiety and depression. A high rate of participants who showed academic excellence (n = 11) was found, who were compared to those with typical academic performance (n = 20). RESULTS: CI was identified in 26 % of participants, primarily in those with typical academic performance, and was associated with disease-related disability (p = .02). In contrast, 45 % showed Personal-CD, particularly in the excellence group (73 %), found associated with depression (p = .01), but not with disease severity. INTERPRETATION: Personal-CD uncovered subtle cognitive decline overlooked by the use of standard CI measures, especially in high-achieving patients. These cognitive changes were associated with depressive symptoms rather than disease severity. Thus, albeit supporting the use of CI as associated with disease severity, the use of Personal-CD highlights also the role of psychological distress in coping with POMS.