Functional connectivity within the Default Mode Network (DMN) shows opposing patterns for anxiety and depression: increased connectivity in anterior regions (medial prefrontal cortex, anterior cingulate cortex) correlates with higher symptom scores, while posterior regions (involved in memory and perception) show decreased connectivity. This dissociation suggests functional specialization within the DMN for self-referential and emotional processes, contributing to understanding cognitive and affective alterations in depressive and anxiety states.
The dopamine β-hydroxylase (DβH) enzyme converts dopamine into noradrenaline. People with low-activity DBH genotypes (rs1611115 CT/TT) appear more sensitive to cannabis and cocaine's effects on cognitive impulse control and brain connectivity. In 122 regular drug users, acute doses of cannabis (450 μg/kg THC) and cocaine (300 mg) increased cognitive impulsivity and reduced functional connectivity between the nucleus accumbens and limbic, prefrontal, striatal, and thalamic areas, primarily in those with CT/TT genotypes, not in those with the CC genotype. A negative association emerged between impulsivity and subcortical connectivity. The findings suggest DBH genotype influences how these drugs affect impulse control and brain networks, potentially explaining progression to drug seeking and informing targeted pharmacotherapy.