Head impacts associated with depression and decreased cognitive function

Head impacts associated with depression and decreased cognitive function

6000 4000 Anna Stelling, PhD

Current research suggests that repetitive head impacts (RHI) resulting from contact sports, military service, domestic violence, or other sources are associated with cognitive and neuropsychiatric disorders.1 It has been proposed that RHI can cause traumatic brain injuries (TBIs) that initiate pathophysiological events ultimately leading to these disorders. However, due to several limitations of available studies, including small cohort sizes, lack of control groups, and retrospective clinical assessments, it remained unclear if RHI can be described as an independent risk factor for neuropsychiatric and cognitive disorders.1 Recently, Michael L. Alosco (Department of Neurology, Boston University School of Medicine, USA) and his team of researchers published the largest ever cross-sectional study comparing measures of depression and cognition from participants with a history of RHI and TBI to a group without such a history.1

Self-report-based assessment of a large cohort

Participants of the study filled out self-report questionnaires about RHI and TBI history. In addition, they had to perform self-report measures of depressive symptoms as well as computer-based neuropsychological tests. In total, the researchers included 13,323 middle-aged and older adults, of which 725 reported RHI mostly due to contact sports and domestic abuse, and 7,277 reported TBI only.1

Higher rates of depression and lower cognitive abilities after head impacts

Dr Alosco and his team found that participants with a history of RHI and TBI both showed more depression symptoms than the control group. They also found a dose-response-like pattern between the amount of head impact exposure and depression symptoms. While the cohort with no exposure to RHI or TBI had the lowest scores on the depression scale, the scores increased with RHI introduction and peaked in the group with both RHI and TBI.  Furthermore, the researchers found that participants with RHI or TBI in their history had worse results in cognitive tests of learning, processing speed, memory, and reaction time. For the majority of test results, the presence of RHI and TBI combined led to worse performance of the participant compared to those suffering from either of the two.1

Great study value despite limitations

Even though the researchers did not have access to the degree of the impact exposure, and the data on RH and TBI are based solely on self-reporting, the results of this large analysis strongly support the previous findings that RHI and TBI both affect neuropsychiatric and cognitive functioning. The authors point out that the lack of granular data on exposure characteristics makes a general interpretation difficult. It was observed that participants with a history of RHI due to contact sports were predominantly male, while those who reported domestic abuse were predominantly female, which gives a natural bias to the results. Given his findings, Dr Alosco summarises in his article, that the “characterization of risk for later-like neurological disorders associated with RHI is of high research priority, specifically in terms of the modifying roles of demographic, psychosocial, psychiatric, health, and genetic variables.”1


References
  1. Alosco ML et al. Neurology. 2020;10:1212
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