Sex differences in the brain

False recall is associated with larger caudate in males but not in females

After learning semantically related words, some people are more likely than others to incorrectly recall unstudied but semantically related lures (i.e., Deese-Roediger-McDermott [DRM] false recall). Previous studies have suggested that neural activity in subcortical regions (e.g., the caudate) is involved in false memory, and that there may be sex differences in the neural basis of false memory. However, sex-specific associations between subcortical volumes and false memory are not well understood. This study investigated whether sex modulates the associations between subcortical volumes and DRM false recall in 400 healthy college students. Volumes of subcortical regions including the caudate, accumbens, amygdala, hippocampus, pallidum, putamen and thalamus were obtained from structural magnetic resonance images and measured using FreeSurfer. The results showed that males had lower true and false recall but larger subcortical volumes than females. Interestingly, higher false recall was associated with a larger caudate in males, but not in females. This association was significant after controlling for age and intracranial volume. This study provides new evidence on the neural basis of false recall. It suggests that the caudate plays a role in false recall in young men, and that future studies of the neural correlates of false memory should consider sex differences.

New cut-off points of PHQ-9 and its variants, in Costa Rica: a nationwide observational study

The PHQ-9 questionnaire is a screening test worldwide used to measure depression. But it cannot be used in Costa Rica, due to the fact that it has not previously been validated for its population. The present study aims to show the validation of the PHQ-9 questionnaire and its variants (PHQ-2, PHQ-4, PHQ-8) in a population sample of adults residing in Costa Rica. A sample was collected (n = 1162) using a self-administered questionnaire. Confirmatory Factor Analysis (CFA), Receiver Operating Characteristic (ROC) curve, and Multiple Group Confirmatory Factor Analysis (MGCFA) were tested. One factor was found that explained 73.33% of the variance with excellent internal consistency (α = 0.928). Goodness-of-fit measures were adequate (RMSEA = 0.107; CFI = 0.948), as was diagnostic power at a cut-off of 10 (78.60 for Sensitivity and 27.95 for 1-Specificity). External validation indices were good (r = 0.843 with GAD-7, r = - 0.647 with RS14, and r = 0.301 with FCV19S), and the model showed invariance by sex (∆χ2 = 27.90; df = 27; p < 0.001). Additionally, new cut-off points were proposed for PHQ-9 and its variants for Costa Rican male, female, and general populations. The PHQ-9 and its variants (PHQ-2, 4, and 8) are valid tools for detecting depression (and anxiety for PHQ-4) in Costa Rican population. In addition, new cut-off points differentiated by sex are proposed.

Environmental contaminants, endocrine disruption, and transgender: Can "born that way" in some cases be toxicologically real?

Gender is viewed by many as strictly binary based on a collection of body traits typical of a female or male phenotype, presence of a genotype that includes at least one copy of a Y chromosome, or ability to produce either egg or sperm cells. A growing non-binary view is that these descriptors, while compelling, may nonetheless fail to accurately capture an individual's true gender. The position of the American Psychological Association (APA) agrees with this view and is that transgender people are a defendable and real part of the human population. The considerable diversity of transgender expression then argues against any unitary or simple explanations, however, prenatal hormone levels, genetic influences, and early and later life experiences have been suggested as playing roles in development of transgender identities. The present review considers existing and emerging toxicologic data that may also support an environmental chemical contribution to some transgender identities, and suggest the possibility of a growing nonbinary brain gender continuum in the human population.