Clinical Correlates of Psychiatric Comorbidities in Patients With Multiple Sclerosis

Overview

Many neuropsychiatric abnormalities associated with multiple sclerosis (MS). These may be broadly divided into 2 categories: disorders of mood, affect,and behavior and abnormalities affecting cognition. With respect to the former, theepidemiology, phenomenology, and theories of etiology are described for the syndromes ofdepression, bipolar disorder, euphoria, pathological laughing and crying, and psychosisattributable to MS. Finally,treatment pertaining to all these disorders is reviewed, with the observation thattranslational research has been found wanting when it comes to providing algorithms toguide clinicians. Guidelines derived from general psychiatry still largely apply, althoughthey may not always be most effective in patients with neurologic disorders. The importance of future research addressing this imbalance is emphasized, forneuropsychiatric sequel add significantly to the morbidity associated with MS.(1) The evolution of the neuropsychiatry of multiple sclerosis(MS), with a set sequence of events unfoldingoverthecourseofacenturyormore,providesahistoricalparadigmforotherneurologicdisorders.Accordingtotheparadigm,aclinically astute neurologist, whom posterity will treat kindly,first describes the neurologic (and occasionally, the psycho-logical) signs and symptomsthat cometo define the disorder. Over succeeding decades, the diagnostic criteria arerefined by further observation supplemented by data fromnew technologies. Mental state changes either pass with littlenoticeoraremissed.Acoupleofgenerationslatercomes belated recognition of prominent abnormalities in mentation-neuropsychiatryredux. . Invariably, the data reveal major psychiatric problems integral to the disease, and then, with fewexceptions, clinical research stops. Few double-blind,placebo-controlled treatment trials in neuropsychiatry provide an evidence-based approach to treating the newly discernedbehaviouralabnormalities. ThelifetimeprevalenceofmajordepressioninMS isapproximately 50% (2). A meta-analysis suggests that this is higherthan in other neurologic disorders (3) and, depending on thereferencepoint,is3to10 timestherateinthegeneral population (4). While the basic phenomenology of the MS depressive syndrome overlaps with that found in primarydepression, certain symptoms are more typical, while othersoccur less commonly. Thus, irritability, discouragement, andasenseoffrustration aremorelikelytoaccompanylowmoodthan are feelings of guilt and poor self-esteem (5). It is alsoimportanttorememberthatsymptomssuchasinsomnia,poorappetite,anddifficultieswithconcentrationandmemorymaybe equally attributable to depression or to MS. Depression is an important reason for so many MS patients'thoughtsofself-harm:suicidalintentoccursinapproximately30% of MS patients and is linked to the presence and severityof depression and social isolation (