Introduction to surfer 12
For instance, men are about 2.5 times more likely to be diagnosed with attention-deficit/hyperactivity disorder (ADHD) than women, whereas women are almost twice as likely to be diagnosed with a mood disorder than men. These are thought to manifest in differences in brain structure and function that emerge in childhood, impacting behavior and vulnerability to neuropsychiatric illnesses including those associated with aberrant dopaminergic function. Differential expression of genes in the sex chromosomes directly contributes to differences in midbrain dopaminergic signaling between men and women. Several lines of research point to sex-based differences in dopamine signaling, with consequences for health outcome disparities. The greater dopamine increases with methylphenidate in ventral but not dorsal striatum in females compared to males suggests an enhanced sensitivity specific to the dopamine reward system that might underlie sex differences in the vulnerability to substance use disorders and to attention-deficit/hyperactivity disorder (ADHD).ĭopamine signaling in the brain is responsible for modulating functions critical for survival, including attention, memory, motor control, motivation, and reward-guided behaviors. In contrast, there were no significant differences in methylphenidate-induced increases in dorsal striatum for either oral or intravenous administration nor were there differences in levels of methylphenidate in plasma. Females when compared to males reported stronger feeling of “drug effects” and showed significantly greater dopamine release in the ventral striatum (where nucleus accumbens is located) to both oral and intravenous methylphenidate.
We analyzed data from two independent raclopride PET brain imaging studies that measured methylphenidate-induced dopamine increases in the striatum using different routes of administration (Cohort A = oral 60 mg Cohort B = intravenous 0.5 mg/kg total n = 95 65 male, 30 female), in blinded placebo-controlled designs. Here we assessed whether there are sex differences in the brain dopamine system in humans that could contribute to these effects.
Sex differences in the prevalence of dopamine-related neuropsychiatric diseases and in the sensitivity to dopamine-boosting drugs such as stimulants is well recognized.