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In This Issue of JAMA Psychiatry
June 2014


JAMA Psychiatry. 2014;71(6):607. doi:10.1001/jamapsychiatry.2013.2733


Lozier and colleagues used an implicit face-emotion processing paradigm to measure amygdala activity associated with callous-unemotional (CU) traits and externalizing behaviors in youths with conduct problems. They found amygdala responses to fearful expression were negatively associated with CU traits and positively associated with externalizing behaviors, and that reduced amygdala activity mediated the relationship between CU traits and proactive aggression.

Nurnberger and colleagues examined genome wide association data in the Psychiatric Genomics Consortium Bipolar Group for information regarding specific genes and neurobiologic pathways associated with bipolar disorder. A set of 226 empirically significant genes was identified, targeting hormonal regulation, calcium channels, second messenger systems, and glutamate signaling. Comparison with a brain gene expression data set implicated neuronal development pathways as well. These results reinforce specific neurobiologic hypotheses regarding bipolar disorder and may suggest new strategies for prevention and treatment.

Using high-resolution magnetic resonance spectroscopic imaging, Goh and colleagues detected significantly elevated brain lactate in individuals with autism spectrum disorder (ASD) (13%), with higher rates in adults (20%) than children (6%). In addition, by mapping lactate in small, contiguous voxels throughout the brain, they identified regions of the brain affected by mitochondrial dysfunction in ASD.

Feder and colleagues reported significant improvement in posttraumatic stress disorder (PTSD) symptom severity 24 hours after a single intravenous infusion of ketamine in patients with chronic PTSD compared with midazolam. Ketamine was also associated with improvement in comorbid depressive symptom severity and overall clinical presentation, with only transient dissociative symptoms.

Continuing Medical Education

By applying the classic twin design to a sample of 10 678 Australian twins, Maciejewski and colleagues found that individual differences in nonsuicidal self-injury and suicidal ideation are both substantially influenced by genetic and residual (including nonshared environmental) factors, while shared environment does not play a role. Furthermore, the substantial phenotypic correlation between both behaviors was largely driven by overlapping genetic influences, whereas overlapping residual influences accounted for the remainder.