Differing associations between measures of somatic symptom reporting, personality, and mild traumatic brain injury (mTBI).

Objective: Somatic complaints are known to complicate recovery after mild traumatic brain injury (mTBI), but the construct is poorly understood due to evolving definitions of associated disorders and uncertainty related to its position within the broader construct network of psychopathology. Methods: To better understand measures of somatic symptom reporting widely used with mTBI patients, we examined relationships between the Brief Symptom Inventory-18 Somatization (SOM) scale, the Minnesota Multiple Personality Inventory-2-Restructured Form Somatic Complaints (RC1) scale, other measures of psychological and personality functioning, and mTBI in both athlete concussion (n = 100) and civilian trauma (n = 75 mTBI, n = 79 orthopedic injury) samples. Results: The association between post-injury SOM and RC1 was moderate (r=.37-.46) and similar to associations between these inventories and depression and anxiety symptoms. In civilians with mTBI, RC1 was more strongly associated with diverse personality dimensions than SOM. mTBI athletes reported increases in somatic symptoms from pre- to post-injury, with larger group effect sizes on SOM (ηp2 = 0.34, p < .001) than RC1 (ηp2 = 0.09, p = .003). Civilian mTBI patients showed a trend for somewhat higher post-injury RC1 scores than orthopedic trauma controls (ηp2 = 0.02, p = .068). Conclusions: Findings add to the current knowledge of the influence of somatic complaints in mTBI. BSI-18 SOM and MMPI-2-RF RC1 are not interchangeable, as they are only modestly correlated and demonstrate differing associations with other clinical outcomes and mTBI.