Schizophrenia is associated with impaired structural and functional brain connectivity; however, it is not known whether this is related to genetic liability for disease. Bohlken and colleagues quantified the contributions of genetic and environmental factors to brain connectivity and disease liability in 70 twins discordant for schizophrenia and 130 healthy twins. They found that lower global fractional anisotropy was correlated with increased schizophrenia liability, suggesting that reduced structural connectivity is largely explained by genetic risk for disease. In an editorial, Cannon discusses how genetic epidemiology can advance intermediate phenotypes research.
The 16p11.2 duplication and deletion are copy number variants frequently associated with autism and schizophrenia. D'Angelo and colleagues compared the phenotypic heterogeneity in 270 duplication and 244 deletion carriers with control subjects. Both copy number variants were associated with a similar decrease in full-scale IQ, but the deletion group showed a consistent downward effect, while the duplication group had an increased proportion of individuals at both extremes of the full-scale IQ. In an editorial, Lord and Veenstra-VanderWeele discuss the value of genetics-first studies in uncovering the links between genotype and phenotypes.
Using DSM-IV definitions of drug use disorders, national survey data indicate that prevalences may have increased. Grant and colleagues used National Epidemiologic Survey on Alcohol and Related Conditions–III, a cross-sectional representative survey of the United States, to assess the prevalence of drug use disorders and several psychiatric disorders using DSM-5 criteria. Prevalences of 12-month and lifetime drug use disorders were 3.9% and 9.9%, respectively. Drug use disorders were significantly associated with other substance use disorders and several psychiatric disorders. Among respondents with lifetime drug use disorders, only 24.6% received treatment.
Bright light therapy is an evidence-based treatment for seasonal depression, but its efficacy in nonseasonal major depressive disorder is unclear. Lam and colleagues conducted a randomized clinical trial of light monotherapy, fluoxetine monotherapy, and combination light with antidepressant treatment. The combination and light monotherapy were significantly superior to placebo in the Montgomery-Asberg Depression Rating Scale change score, but fluoxetine monotherapy was not superior to placebo. All treatments were generally well tolerated.
Continuing Medical Education
People with epilepsy have a 5-fold increased risk of completed suicide, but it is not known whether psychiatric disorders and antiepileptic drugs modify suicide attempt risk. Hesdorffer and colleagues analyzed suicide attempt data from a representative sample of more than 70 000 people aged 10 to 60 years and followed up by general practitioners in the United Kingdom. The risk of first and recurrent suicide attempts were significantly higher (2.9- and 1.8-fold, respectively) in persons who later had onset of epilepsy, regardless of whether they had been prescribed antiepileptic medication or had diagnosable psychiatric disorders.
Highlights. JAMA Psychiatry. 2016;73(1):1. doi:10.1001/jamapsychiatry.2015.1600