Body mass index and somatic symptom severity in patients with somatic symptom disorder: the mediating role of working memory
Hee Jin Kim 1, Hye Ri Kim 1, Jae-Chan Jin 2, Doug Hyun Han 1, Sun Mi Kim 1*
1Department of Psychiatry, Chung-Ang University College of Medicine, Seoul, Korea, 2Department of Social Welfare, Graduate School of Soongsil University, Seoul, Korea
Received: June 3, 2020; Revised: July 23, 2020; Accepted: July 30, 2020; Published online: July 30, 2020.
© The Korean College of Neuropsychopharmacology. All rights reserved.

Objective: In somatic symptom disorder (SSD), cognitive dysfunction is related to perceptive distortion that excessively amplifies bodily sensations. The association between high body mass index (BMI) and cognitive dysfunction could be attributed to underlying systemic inflammation. We aimed to evaluate whether patients with SSD and high BMI exhibit increased somatic symptom severity and whether this is mediated by cognitive dysfunction.
Methods: This retrospective, cross-sectional study was conducted on 54 patients with SSD (20 men/34 women, mean age ± standard deviation: 40.65 ± 13.23 years). Participants’ BMI, laboratory data including complete blood count and lipid profile, results from the Korean Wechsler Adult Intelligence Scale-IV, and scores of the Korean-Symptom Checklist 95-Somatization (SCL95-SOM) were analyzed. We performed a path analysis to evaluate BMI as a predictor of somatic symptoms.
Results: In a path analysis, the SCL95-SOM score was directly influenced by working memory (b = -0.326, P = 0.032), which was significantly influenced by BMI (b = -0.338, P = 0.009), although there was no direct effect of BMI on the SCL95-SOM score. The path analytic model showed a close fit to the data with the following values: χ2 (df) = 0.918 (1), P = 0.338, root mean square error of approximation = 0.000 (< 0.001), and comparative fit index = 1.00.
Conclusion: Patients with SSD and high BMI may exhibit increased somatic symptom severity, and this is mediated by working memory dysfunction. Weight management may help improve symptoms in patients with SSD and high BMI.
Keywords: Somatoform disorder, Medically unexplained syndrome, Body mass index, Working memory, Cognitive dysfunction