Effects of Subconcussive Head Injury on Anxiety

Pediatric traumatic brain injury (TBI) is the leading cause of death and disability in children and affects approximately 322,000 children under the age of nine every year. Thus, concussion rates and outcomes in adolescents and young adults have received much attention in recent years. Separately from concussions, repeated subconcussive head injury is thought to increase risk for cognitive and behavioral decline. In particular, the relationship between subconcussive head injury and mental health requires study. For example, the effects of subconcussive head injury on ability to manage anxiety remain unknown. Previous work has shown that TBI can lead to deficits in ability to manage anxiety. The present study examined the relationship between subconcussive head injury and ability to manage anxiety. Subconcussive head injury frequency and severity was measured using a subconcussive head injury scale adapted from Marchi et al. (2013). Results revealed no significant correlation between scores on the anxiety inventory and scores on the subconcussive head injury scale. Findings from this study imply that an increased number of head hits does not lead to an increase of anxiety symptoms. SUBCONCUSSIVE HEAD INJURY 3 Effects of Subconcussive Head Injury on Anxiety Head Injury Chronic traumatic encephalopathy (CTE) is a progressive degenerative disease of the brain found in people with a history of repetitive brain trauma (Spiotta, Shin, Bartsch, & Benzel, 2011). While the incidence, prevalence, and possible short and long term health consequences of concussions are well described (Wiebe, Comstock, & Nance, 2011), the effects of repeated subconcussive head injuries remain unclear. Subconcussive head injuries result from rapid cranial impact following a head hit during the deceleration of the body following initial impact which lead to long-term neurological deficits, but are not recognized as concussions (Bailes et al., 2013). Several highly publicized cases of professional athletes who died at a young age were later found to have CTE. Currently, the effects of subconcussive head injury are not being studied in the general population. A general population cohort would include participants who have occupational hazards that may include subconcussive head injuries, victims of abuse who sustained a subconcussive head hit, epileptics, and participants who may have sustained subconcussive head injuries from everyday activities. Accumulated subconcussive head injuries have been hypothesized to contribute to the long-term consequences of contact sport participation (Broglio, & Guskiewicz, 2014; Spiotta, Shin, Bartsch, & Benzel, 2011). McCalister et al. (2012) conducted a study of head hit impact on cognitive performance using collegiate football and hockey players. They found athletes’ scores on performance tests for new learning were significantly negatively correlated with greater head impact exposure experienced over the duration of one playing season (McCalister et al., 2012). Yet, none of the athletes in SUBCONCUSSIVE HEAD INJURY 4 the study had a diagnosed concussion. Talavage et al. (2014) studied the effects of head hits obtained during the playing season had on neurological functioning during the playing season, and about three months after the season ended, using high school football players. They found that the football players who did not report having a prior concussion, still had significant neurological deficits and impairment to the prefrontal cortex. Studies such as this one underscore the need for further research into the short and long term consequences of subconcussive head injuries. Symptoms of concussion can occur with no noticeable changes in pathology, and may be so subtle that even an MRI would not be able to detect them (Van Kampen et al., 2006). Concussion under diagnosis suggests that a subconcussive head injury, where an individual does not quite meet the threshold for a concussion diagnosis, is largely undetected in the general population. Moreover, as subconcussive head injuries are not a recognized medical condition (unlike concussion), tracking the effect of this condition hasn’t occurred in the health care system. However, if subconcussive head injuries lead to negative outcomes, recognizing and tracking them will be important to improve health care. Symptoms associated with having a concussion have been shown to last years after the initial impact. Moreover, mental illnesses associated with repeated concussion include depression, anxiety, and post traumatic stress disorder (Bryan, 1999). Indeed, many of the long-term effects of concussion overlap with symptoms of anxiety disorders. The following symptoms are included in the detection of post-concussive syndrome: fatigue, headaches, dizziness, sleep disturbance, difficulty concentrating, irritability, apathy or affective disturbance, or personality changes (Barlow, 2014; Brown, SUBCONCUSSIVE HEAD INJURY 5 Campbell, Lehman, Grisham, & Mancill, 2001). Thus, the symptoms that overlap between post-concussive symptoms and general anxiety disorder include: difficulty concentrating, irritability, and sleep disturbances (Yuelong, 2014). The overlap of symptoms between post-concussive symptoms and anxiety may suggest that damage to brain circuits involved with mediating anxiety could lead to the development of an anxiety disorder. Willer & Leddy (2006) stated that patients with post-concussive symptoms might have semi-permanent brain injury, therefore the structural changes in the brain of the individual have not returned to the same orientation as before their brain injury (Willer & Leddy, 2006). This may suggest that further research is needed to find if post-concussive symptoms and anxiety are due to the semi-permanent damage of brain structures associated with anxiety. Despite the possible role of subconcussive head injuries in producing long term brain and behavior abnormalities, brain injury prevention efforts in youth and adult contact sports have typically focused on minimizing only an athlete's concussive episode risk. Although the effect of repetitive subconcussive trauma in contact sports has received increased attention recently, it has yet to be fully addressed (Spiotta, Shin, Bartsch, & Benzel, 2011). With more awareness and funding being put towards head injury research, researchers are beginning to pursue studies in subconcussive head injury. For example, specific neuropsychological test are being developed to detect frequency of subconcussive head injuries. One such tool, the Head Hit Index, developed by Dr. Damir Janigro of the Cleveland Clinic measures subconcussive head injury frequency and severity. SUBCONCUSSIVE HEAD INJURY 6