The post-concussion syndrome (PCS) is relatively common following mild traumatic brain injury (MTBI). However, the factors that cause and maintain this syndrome continue to be debated. The purpose of this investigation was to examine the prevalence of postconcussion-like symptoms in a sample of healthy individuals. Participants (N = 104) completed the British Columbia Postconcussion Symptom Inventory-Short Form (BC-PSI-Sf), a test designed to measure both the frequency and intensity of ICD-10 criteria for PCS, and the Beck Depression Inventory (2nd ed.). Specific endorsement rates of postconcussion-like symptoms ranged from 35.9% to 75.7% for any experience of the symptoms in the past 2 weeks, and from 2.9% to 15.5% for the experience of more severe symptoms. Symptoms reported on the BC-PSI-Sf also showed a moderately high correlation with self-reported depressive symptoms [r (102) =.76, p <.01]. This study illustrates that the presence of postconcussion-like symptoms: (a). are not unique to mild head injury and are commonly found in healthy individuals, and (b). are highly correlated with depressive symptoms.

This study examined multiple biopsychosocial factors relating to post-concussion symptom (PCS) reporting in patients with mild traumatic brain injuries (mTBI), including structural (computed tomography and magnetic resonance imaging [MRI]) and microstructural neuroimaging (diffusion tensor imaging [DTI]). Patients with mTBIs completed several questionnaires and cognitive testing at approximately one month (n=126) and one year (n=103) post-injury. At approximately three weeks post-injury, DTI was undertaken using a Siemens 3T scanner in a subgroup (n=71). Measures of fractional anisotropy were calculated for 16 regions of interest (ROIs) and measures of apparent diffusion coefficient were calculated for 10 ROIs. Patients were compared with healthy control subjects. Using International Classification of Diseases, Tenth Revision (ICD-10) PCS criteria and mild or greater symptom reporting, 59% of the mTBI sample met criteria at one month and 38% met criteria at one year. However, 31% of the healthy control sample also met criteria for the syndrome-illustrating a high false-positive rate. Significant predictors of ICD-10 PCS at one month were pre-injury mental health problems and the presence of extra-cranial bodily injuries. Being symptomatic at one month was a significant predictor of being symptomatic at one year, and depression was significantly related to PCS at both one month and one year. Intracranial abnormalities visible on MRI were present in 12.1% of this sample, and multifocal areas of unusual white matter as measured by DTI were present in 50.7% (compared with 12.4% of controls). Structural MRI abnormalities and microstructural white matter findings were not significantly associated with greater post-concussion symptom reporting. The personal experience and reporting of post-concussion symptoms is likely individualized, representing the cumulative effect of multiple variables, such as genetics, mental health history, current life stress, medical problems, chronic pain, depression, personality factors, and other psychosocial and environmental factors. The extent to which damage to the structure of the brain contributes to the persistence of post-concussion symptoms remains unclear.

These findings suggest that chronic post-concussive symptoms following an mTBI relate to altered exosomal activity, and that greater tau pathology may underlie chronic post-concussive symptoms that develop following mTBIs. It also suggests that central inflammatory activity contributes to PTSD symptoms following an mTBI, providing necessary insights into the role of inflammation in chronic PTSD symptoms.