Pain is associated with prospective memory dysfunction in multiple sclerosis

Abstract

Prospective memory (PM) pertains to the execution of a future goal or behavior. Initial research implies that people with multiple sclerosis (MS) are apt to show impaired prospective memory for activities of daily living. Yet, PM impairment does not occur in all people with MS. Thus, some other variable besides disease status alone may contribute to PM dysfunction in people with MS. Chronic pain may be such a variable. Approximately 50–70% of people with MS experience significant pain, and such pain has been thought to diminish memory function. To investigate this possibility, 96 patients with MS and 29 healthy subjects were administered the Memory for Intentions Screening Test (MIST; Woods, S. P., Iudicello, J. E., Moran, L. M, Carey, C. L., Dawson, M. S., & Grant, I. (2008). HIV-associated prospective memory impairment increases risk of dependence in everyday functioning. Neuropsychology, 22, 110–117.), a well-validated measure of prospective memory, and the Medical Outcomes Study Pain Effects Scale (PES; Fischer, J. S., Rudick, R. A., Cutter, G. R., & Reingold, S. C. (1999). The multiple sclerosis functional composite measure (MSFC): An integrated approach to MS clinical outcome assessment. National MS Society Clinical Outcomes Assessment Task Force. Multiple Sclerosis, 5, 244–250.) to assess chronic pain. After controlling for demographic variables and disability severity, subjective pain accounted for significant variance in PM, particularly for time-based intentions over sustained delay periods. These data accord well with assertions that pain may degrade ability to remember new intentions and suggests that pain is associated with PM dysfunction in people with MS.