Temporal Processing in Multiple Sclerosis: A Selective Cognitive Vulnerability

Background Cognitive impairment in Multiple Sclerosis (MS) extends beyond classical domains such as processing speed and memory, yet temporal aspects of cognition remain underexplored. Temporal cognition including time estimation, memory for time, and future oriented thinking is essential for organising experience, sequencing events, and supporting prospective behaviour. These functions rely on cognitive systems such as memory, attention, executive control, and processing speed, and on brain regions commonly affected in MS, including frontal, temporal, and parietal areas, suggesting that temporal cognition may also be vulnerable in this condition. Despite this, no study has examined temporal cognition in MS across present , past and future oriented processes, nor investigated how performance in these domains relates to structural disease burden such as lesion volume. Objectives This study aimed to characterise temporal cognition in MS by assessing memory for time (past), interval timing (present), and future oriented thinking (future) using a naturalistic, ecologically grounded paradigm. A further objective was to determine whether performance across these domains is associated with clinical variables linked to disease severity and burden, including EDSS, T2 lesion load, and disease duration. Methods 28 PwMS (age 38±10 years; education 16.2±3 years; disease duration 10.7±11 years; EDSS 2.5±1.5) and 45 matched healthy controls viewed a full television episode and subsequently completed temporal cognition tasks. Past oriented processes were assessed through temporal order reconstruction, recency discrimination, and temporal distance estimation. Present oriented processes were evaluated using an interval reproduction task with regular and irregular auditory sequences. Future oriented thinking was assessed through questionnaires measuring general future orientation and future self projection. Correlations with EDSS, T2 lesion load, and disease duration were computed Results PwMS showed marked impairments in memory for time, with reduced recency accuracy (p = .011), larger errors in temporal reconstruction (p < .001), and greater duration estimation errors (p < .001). Interval timing was relatively preserved, with no group differences for regular intervals (p = .495) and only a trend toward reduced accuracy for irregular intervals (p = .077). Future oriented thinking showed a dissociation: general future orientation was preserved (p = .172), whereas future self projection was reduced (p = .032). No temporal cognition measure correlated significantly with EDSS, T2 lesion load, or disease duration (all p > .28). Conclusion PwMS show a selective pattern of impairment in temporal cognition, particularly affecting memory for time and future self projection, while basic interval timing remains relatively preserved. Temporal cognition emerges as a clinically relevant and previously overlooked dimension of MS cognitive impairment, with potential implications for more sensitive neuropsychological assessment.