Signs and symptoms of multiple sclerosis (MS) may overlap with those of depression, a common comorbidity. This study explored whether inclusion of somatic items on the Beck Depression Inventory-II (BDI-II) falsely elevated scores in a clinical sample of 557 adults with MS evaluated by the health psychology service within an MS center. Our sample's BDI-II responses were subjected to exploratory factor analysis, and the results were compared with those reported in the BDI-II manual. Analyses were then conducted to compare patients who identified fatigue as their worst MS symptom with those who did not and to compare those with high and low levels of fatigue and daytime sleepiness in terms of total BDI-II score, percentage contribution of specific somatic items (ie, tiredness or fatigue) to total BDI-II score, and the sum contribution of the somatic-affective factor to the BDI-II score. Respondents who reported fatigue as their worst MS symptom and those who did not had almost identical BDI-II scores. Among patients reporting fatigue as their worst symptom, only the “loss of energy” item was significantly higher, as was the “tiredness or fatigue” item among patients with severe fatigue. Percentage contribution of the somatic-affective factor to the total BDI-II score did not differ significantly by the presence of fatigue as the worst MS symptom or level of daytime sleepiness. In conclusion, somatic items do not necessarily confound depression scores for individuals with MS and should be retained when using the BDI-II to assess depression in this population.

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Author notes

From the Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA (PC); and Department of Sociology, Case Western Reserve University, Cleveland, OH, USA (NJW). At the time this study was conducted, Dr. Crawford was affiliated with the Cleveland Clinic, Cleveland, OH, USA.