Mild traumatic brain injury (mTBI) is a relatively common occurrence, but the mental health consequences are poorly understood. Stein and colleagues conducted a cohort study of 1155 patients with mTBI to examine mental health sequalae. Rates of posttraumatic stress disorder and major depressive disorder ranged from 9% to 19%, and some individuals, on the basis of education, race/ethnicity, and psychiatric history, were at substantially increased risk of mental health problems following mTBI. These findings highlight the importance of monitoring for mental health problems following mTBI, particularly for high-risk individuals.
Infections have been associated with increased risks for specific mental disorders, but the association between infections requiring treatment and the wide range of mental disorders is unknown. Using the Danish national registry, Köhler-Forsberg and colleagues found that infections requiring hospitalization or treatment with anti-infective agents were significantly associated with subsequent increased risk of any mental disorder and increased risk of redeeming a prescription for psychotropic medication. These findings provide evidence for the involvement of infections in a wide range of psychiatric disorders. In an Editorial, Labrie and Brundin discuss mechanistic implications.
Psychiatric traits associated with categorically defined psychiatric disorders are present to varying degrees in the population, but it is not known whether these represent milder forms in continuous variation with the disorder. Using the Swedish population twin sample and a novel twin analytic approach with polygenic risk scores, Taylor and colleagues found that disorder polygenic risk scores were significantly associated with related population traits for a wide range of psychiatric disorders. These results suggest that many psychiatric disorders are likely to be continuous phenotypes rather than categorical entities.
Major depression is associated with cognitive abnormalities, but it is not known whether these are part of a preexisting vulnerability rather than a consequence of depression or its treatment. In a meta-analysis encompassing 54 samples and 3246 first-degree relatives of individuals with depression, MacKenzie and colleagues found that relatives of people with depression performed significantly worse than control individuals across all measures of cognition. These results indicate that cognitive impairment is a feature of familial predisposition to depression. In an Editorial, Halahakoon and colleagues discuss the implications of this finding for the field.
Depression often manifests first in adolescence, but it is not known what shapes depression trajectories in youths. In a sample comprising 7543 adolescents from a prospective, longitudinal, population-based cohort, Rice and colleagues identified a persistently low depression trajectory, a late-onset trajectory associated with genetic risk for major depressive disorder, and an early-onset trajectory associated with genetic risk for depression but also neurodevelopmental disorders, attention-deficit/hyperactivity disorder, and social communication difficulties. These results suggest a neurodevelopmental component in some cases of early-onset depression.