Chronic Hypopituitarism Associated with Increased Postconcussive Symptoms Is Prevalent after Blast-Induced Mild Traumatic Brain Injury

Abstract

The most frequent injury sustained by US service members deployed to Iraq or Afghanistan is mild traumatic brain injuries (mTBI), or concussion, by far most often caused by blast waves from improvised explosive devices or other explosive ordnance. TBI from all causes gives rise to chronic neuroendocrine disorders with an estimated prevalence of 25–50%. The current study expands upon our earlier finding that chronic pituitary gland dysfunction occurs with a similarly high frequency after blast-related concussions. We measured circulating hormone levels and accessed demographic and testing data from two groups of male veterans with hazardous duty experience in Iraq or Afghanistan. Veterans in the mTBI group had experienced one or more blast-related concussion. Members of the deployment control (DC) group encountered similar deployment conditions but had no history of blast-related mTBI. 12 of 39 (31%) of the mTBI participants and 3 of 20 (15%) veterans in the DC group screened positive for one or more neuroendocrine disorders. Positive screens for growth hormone deficiency occurred most often. Analysis of responses on self-report questionnaires revealed main effects of both mTBI and hypopituitarism on postconcussive and posttraumatic stress disorder (PTSD) symptoms. Symptoms associated with pituitary dysfunction overlap considerably with those of PTSD. They include cognitive deficiencies, mood and anxiety disorders, sleep problems, diminished quality of life, deleterious changes in metabolism and body composition, and increased cardiovascular mortality. When such symptoms are due to hypopituitarism, they may be alleviated by hormone replacement. These findings suggest consideration of routine post-deployment neuroendocrine screening of service members and veterans who have experienced blast-related mTBI and are reporting postconcussive symptoms.

Neuroendocrine Abnormalities Following Traumatic Brain Injury: An Important Contributor to Neuropsychiatric Sequelae

“…A military survey of soldiers returning from Iraq reported 44% of troops who had sustained mild TBIs with loss of consciousness screened positive for PTSD as compared to 16% who sustained only bodily injury ( 127 ). Additionally, a very recent study of veterans returning from dangerous posts in Iraq or Afghanistan found significant main effects of mild TBI on self-report questionnaires measuring PTSD symptoms ( 60 ). From an experimental angle, an animal study by Elder and others found that blast exposure causing mild TBI in anesthetized mice provoked PTSD-related traits, such as increased startle response (i.e., anxiety), enhanced contextual fear response, altered response in a predator scent assay, and increased expression of a protein involved in the fear response, suggesting that frank structural injury from the blast may have been the cause of the symptoms rather than memory of the event ( 120 ).…”

“…This is nonetheless speculative at this point. And yet, one aforementioned study of veterans did report intriguing results: using self-report questionnaires to investigate the relationship between TBI, overall hypopituitarism, and PTSD, the authors revealed a significant main effect of TBI-induced hypopituitarism on questionnaires assessing PTSD symptoms ( 60 ).…”

“…Therefore, it comes as no surprise that these same symptoms after head trauma that were once regarded simply under the umbrella of post-concussive syndrome are being reconsidered in the context of PHTH and specifically post-TBI GHD. Moreover, many symptoms of post-traumatic stress disorder (PTSD) overlap with those of TBI, and questions have arisen whether neuroendocrine pathologies may contribute to PTSD in the setting of head trauma ( 59 , 60 ). Although it is extremely complicated to parse out which symptoms attributed to PTSD may be specifically linked to brain injury as such, knowing what symptoms may be due to neuroendocrine abnormalities is being given special attention ( 61 ).…”

Neuroendocrine consequences of traumatic brain injury and strategies for management

“…In a recent study, it was reported that 31% of veterans who at least had one blast-related mild TBI developed PD, while the rate was 15% among the control group. It was stated that the symptoms of PD overlapped significantly with those of posttraumatic stress disorder (PTSD) (9). The rate of PD due to sportsrelated TBIs was reported to range from 15% to 46.6% (10).…”

Neuroendocrine function and associated mental health outcomes following mild traumatic brain injury in OEF‐deployed service members

“…Accumulating evidence suggests TBI impairs the hypothalamic‐pituitary‐adrenal axis, resulting in clinical manifestations resembling post‐concussive symptoms (Bondanelli et al, ; Undurti et al, ; West & Sharp, ; Wilkinson et al, ). Both acute and persistent neuroendocrine dysfunction (NED) can have a profound impact on health outcomes following mTBI.…”