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Forensic Updates

Unraveling the Complex Interaction between Traumatic Brain Injury and Psychiatric Disorders

Dr. Sam Goldstein

Perhaps no greater challenge faces the forensic neuropsychologist today than the differential diagnosis of impairment secondary to emotional and mental health disorders versus chronic pain and/or traumatic brain injury. This challenge is amplified in cases of mild Traumatic Brain Injury in the approximate 15% to 20% of that group suffering from persistent concussive symptoms, or as it is sometimes referred to, a Persistent Post-Concussive Disorder. In forensic neuropsychology, this issue is particularly salient as I am typically asked to offer an opinion concerning the apportionment of etiology when multiple, possible explanations for symptoms and impairments are present.

It is well understood that individuals suffering from post-accident chronic pain, psychiatric disorders such as Post Traumatic Stress Disorder, as well as Traumatic Brain Injury, can exhibit very similar profiles of daily functional impairment involving what I have referred to in my work as “impairment in cognitive efficiency.” Impairment in cognitive efficiency is defined as the discrepancy between an individual’s capabilities and their actual functioning in everyday life. For example, chronic pain can impair real life concentration and incidental memory leading to daily challenges at home and in the workplace. So too can Post Traumatic Stress Disorder, Generalized Anxiety and Depression. This pattern of inefficiency is also one of the most characteristic presentations of individuals suffering a Traumatic Brain Injury. The available scientific literature provides some assistance and guidance in the differential diagnostic process. However, there continues to be a dearth of literature examining the cognitive impairments in individuals with chronic pain and psychiatric disorders, while researchers have taken great interest in understanding and defining the adverse emotional and behavioral consequences experienced by individuals suffering from Traumatic Brain Injury. Neuropsychological testing is helpful as well but only adds a small part in explaining the etiology of daily problems in all but the most extreme case.

In this legal update, I will briefly review recent research concerning the onset and presentation of emotional and behavioral challenges in children and adults suffering from Traumatic Brain Injury as well as provide guidelines I employ as a forensic neuropsychologist to approach this issue in a reasoned and reasonable manner.

A recent large-scale study 1 integrating and analyzing the genome-wide association of twenty-five brain disorders finds that psychiatric disorders broadly share a considerable portion of their common variant gene risk, especially across conditions such as depression and anxiety. In contrast, neurological disorders such as diseases or those related to Traumatic Brain Injury, share relatively little common genetic risk. This suggests multiple different and largely independent pathways that may give rise to similar clinical manifestations (e.g., someone with a TBI may share many symptomatic characteristics of someone suffering from chronic depression). Further, the high degree of genetic correlation among these psychiatric disorders adds further evidence that current clinical diagnostic protocols do not reflect specific genetic etiology for these disorders and those genetic risk factors for psychiatric disorders do not respect clinical diagnostic boundaries. It is precisely for this reason that the current Diagnostic and Statistical Manual of the American Psychiatric Association in its fifth edition raises concerns about the use of these diagnostic entities in high stakes situations such as litigation. This problem only further complicates the differential diagnostic etiology of an individual suffering from an accident causing physical and psychological injury presenting for forensic evaluation.

In a recent large scale meta-analysis2 (a study combining many other studies), David Perry and colleagues found a significant relationship between TBI and the subsequent development of neurologic and psychiatric disorders. They also found higher risk for the development of conditions such as Alzheimer’s and Parkinson’s Disease. Interestingly this association was present in the examination only of mild traumatic brain injury cases. Further, this study found, contrary to popular belief, that multiple TBI’s were not associated with higher odds of disease than a single TBI. It is fair to conclude that a history of even a mild TBI is associated with the development of neurologic and psychiatric illness. TBI is either a risk factor for a heterogeneous, pathologic process or TBI may contribute to a common pathologic mechanism.

In a similar analysis, involving mild traumatic brain injury in children and adolescents, Carolyn Emery and colleagues3 examined thirty studies concluding that few rigorous, prospective studies have examined the psychological, behavioral and psychiatric outcomes in children following mild Traumatic Brain Injury. In the absence of reports of pre-injury problems when ideally comparing mild TBI to non-TBI injured controls, there is little evidence to suggest that psychological, behavioral and/or psychiatric problems persist beyond the acute and sub-acute period following a mild Traumatic Brain Injury in children and adolescents. In contrast to the findings with adults, many of these problems appear to resolve in most cases. Children with the greatest risk for longer term problems appeared to be those with multiple previous mild TBIs or pre-existing psychiatric illness. The authors acknowledge that much better studies are needed noting that future research must focus on high quality, prospective longitudinal data in an effort to understand the long-term risks of mild Traumatic Brain Injury in children.

In a twenty-four-month follow-up in children and adolescents following mild Traumatic Brain Injury, Jeffrey Max and colleagues4 suggested that their findings support that psychiatric morbidity for at least a twenty-four-month period in children suffering from mild Traumatic Brain Injury is more common than previously thought, and that it is also linked to pre-injury vulnerabilities and variables related to both developmental and psychiatric disorders. It should be noted that this was a group of children who were hospitalized and had positive brain findings as the result of their injuries. These authors suggest that not only did neuropsychiatric disorders persist but they appeared to be common in approximately a third of the prospectively studied children. Most of these challenges emerged in the first weeks post-injury.

Finally, Haghsma and colleagues5, in a population of adults with Traumatic Brain Injury, reported that rates of depression and Post Traumatic Stress Disorder at six and twelve-month follow-ups were 7% and 9% respectively. Depression and PTSD was associated with the significantly decreased functional outcome and quality of life. These disorders appeared to be relatively common in this sample and associated with a considerable decrease in functional outcome and quality of life.

It is apparent that even good research does not provide consistent guidelines to appreciate and understand the cause and effect relationship between psychiatric problems, chronic pain and TBI in symptom presentation and impairment, as well as course over time for these conditions. It is an overly simplistic position for a forensic expert to take suggesting that single variables such as group data, test scores, past psychiatric history or even severity of accident forces, can be used in isolation to offer opinions as to the etiology of presenting impairments in everyday life. In these complex cases, I make an effort to carefully collect all available pre-accident and post-accident educational, vocational, medical, mental health data, as well as any and all records that might provide a profile of an individual’s pre and post-accident life functioning. I am also increasingly focusing on measures of ability versus acquired knowledge. Neuropsychological assessment tools evaluating planning, attention, processing speed, working memory and other behaviors falling under the umbrella of executive functioning, are critically important to evaluate. Further, we are observing an increase in the development of computer-based tools such as Nesplora’s Virtual Reality Aquarium designed to evaluate attention and executive functioning in adults and Neurotech’s MOXO continuous performance measure designed to assess attention, vigilance, motor response and regulation. Finally, there are many cases in which firm conclusions cannot be made concerning the etiologic contribution of pre-existing mental health or chronic pain problems, accident related emotional and physical adversity or other post-accident life challenges. The forensic evaluator must take a reasoned and reasonable approach always keeping in mind that as forensic evaluators we are not advocates but rather interpreters of the available science, data and resources.

References

1Arttila, V., et al. ( 2015) Analysis of shared heritability and common disorders of the brain. Science, 360, 1313-1325.
2Perry, D.C., et al. (2016). Traumatic brain injuries associated with subsequent neurologic and psychiatric disease: A meta-analysis. Journal of Neurosurgery, 124, 511-526.
3Emery, C.A., et al. (2016). A systematic review of psychiatric, psychological and behavioural outcomes following mild traumatic brain injury in children and adolescents. Canadian Journal of Psychiatry, 61, 259-269.
4 Max, J.E., et al. (2015). Psychiatric disorders in children and adolescents twenty-four months after a mild traumatic brain injury. Journal of Neuropsychiatry and Clinical Neuroscience, 27, 112-120.
5 Haghsma, J.A., et al. (2015). The impact of depression and post-traumatic stress disorder on functional outcome and health related quality of life of patients with mild traumatic brain injury. Journal of Neurotrauma, 32, 853-862.