Differential functional specialization of the left and right hemispheres for linguistic and emotional functions, respectively, suggest that interhemispheric communication via the corpus callosum is critical for emotional awareness. Accordingly, it has been hypothesized that the age-related decline in callosal connectivity mediates the frequently demonstrated reduction in emotional awareness in older age. The present study tests this hypothesis in a sample of 307 healthy individuals between 20–89 years using combined structural and diffusion-tensor magnetic resonance imaging (MRI) of the corpus callosum. As assumed, inter-hemispheric connectivity (midsagittal callosal area and thickness, as well as fractional anisotropy, FA) and emotional awareness (i.e., increase in externally-oriented thinking, EOT; assessed with the Toronto Alexithymia Scale, TAS-20) were found to be reduced in older (> 60 years) compared to younger participants. Furthermore, relating callosal measures to emotional awareness, FA in the genu of the corpus callosum was found to be negatively correlated with EOT in male participants. Thus, “stronger” structural connectivity (higher FA) was related with higher emotional awareness (lower EOT). However, a formal mediation analysis did not support the notion that age-related decline in emotional awareness is mediated by the corpus callosum. Thus, the observed reduction of emotional awareness and callosal connectivity in older age likely reflects parallel but not inter-dependent processes.
Objective Prenatal opioid exposure has been linked with impaired cognitive development, with boys potentially at elevated risk. In the present study, we examined cognitive and language development of children prenatally exposed to opioids, with an additional focus on sex differences. Methods A sample of 378 children (n = 194 girls and n = 184 boys) aged 1.2–42.8 months was drawn from the Danish Family Outpatient Clinic database. Developmental outcomes were assessed using the Bayley-III cognitive and language scales, and substance exposure was determined with urine screening and/or verbal report. Children exposed to opioids (n = 94) were compared to children with no prenatal substance exposure (n = 38), and children exposed to alcohol (n = 131) or tobacco (n = 115). Group and sex differences were investigated with separate linear mixed models for each Bayley scale, controlling for concurrent cannabis exposure. Results There were significantly reduced scores in opioid-exposed boys compared to boys with no prenatal substance exposure, but no difference between opioid-exposed and nonexposed girls. Additionally, alcohol-exposed boys had lower cognitive scores than nonexposed boys, and alcohol-exposed girls had lower scores on both scales compared to opioid-exposed girls. There were otherwise no significant differences according to group, sex, or scale. Conclusions The present findings indicate poorer cognitive and language development in boys after prenatal opioid exposure. As academic performance is rooted in cognitive functioning, long-term follow-up might be necessary for exposed children.
Chronic use of drugs may alter the brain’s reward system, though the extant literature concerning long-term cannabis use and neural correlates of reward processing has shown mixed results. Adolescents may be more vulnerable to the adverse effects of cannabis than adults; however, this has not been investigated for reward processing. As part of the ‘CannTeen’ study, in the largest functional magnetic resonance imaging study of reward processing and cannabis use to date, we investigated reward anticipation and feedback in 125 adult (26–29 years) and adolescent (16–17 years) cannabis users (1–7 days/week cannabis use) and gender- and age-matched controls, using the Monetary Incentive Delay task. Blood-oxygen-level-dependent responses were examined using region of interest (ROI) analyses in the bilateral ventral striatum for reward anticipation and right ventral striatum and left ventromedial prefrontal cortex for feedback, and exploratory whole-brain analyses. Results showed no User-Group or User-Group × Age-Group effects during reward anticipation or feedback in pre-defined ROIs. These null findings were supported by post hoc Bayesian analyses. However, in the whole-brain analysis, cannabis users had greater feedback activity in the prefrontal and inferior parietal cortex compared to controls. In conclusion, cannabis users and controls had similar neural responses during reward anticipation and in hypothesised reward-related regions during reward feedback. The whole-brain analysis revealed tentative evidence of greater fronto-parietal activity in cannabis users during feedback. Adolescents showed no increased vulnerability compared with adults. Overall, reward anticipation and feedback processing appear spared in adolescent and adult cannabis users, but future longitudinal studies are needed to corroborate this.
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