A randomized controlled trial of intermittent theta burst stimulation to the medial prefrontal cortex for tobacco use disorder: Clinical efficacy and safety.

OBJECTIVE: This study aimed to evaluate the clinical efficacy and safety of administering intermittent theta burst stimulation (iTBS) to the medial prefrontal cortex for tobacco use disorder. METHODS: A randomized sham-controlled trial was conducted, with 38 participants receiving 28 sessions of active (n=25) or sham (n=13) iTBS (2 sessions/day, 600 pulses/session, 110% resting motor threshold, AFz target) along with smoking cessation education (Forever Free © booklets) over 14 visits. Primary outcomes included self-reported cigarette consumption and abstinence, verified by urinary cotinine tests. Secondary outcomes included symptoms of tobacco use disorder, negative mood, and safety/tolerability. RESULTS: Both active and sham groups reported reduced cigarette consumption (ß = -0.12, p = 0.015), cigarette craving (ß = -0.16, p = 0.002), and tobacco withdrawal symptoms (ß = -0.05, p < 0.001). However, there were no significant time x group interaction effects for any measure. Similarly, the two groups had no significant differences in urinary cotinine-verified abstinence. Adverse events occurred with similar frequency in both groups. CONCLUSION: There were no differences in cigarette consumption between the active and sham iTBS groups, both groups decreased cigarette consumption similarly. Further research is needed to compare iTBS to standard high-frequency rTMS and explore the potential differences in efficacy. Despite limitations, this study contributes to experimental design considerations for TMS as a novel intervention for tobacco and other substance use disorders, emphasizing the need for a more comprehensive understanding of the stimulation parameters and target sites.

Striatal dopamine D2-type receptor availability and peripheral 17ß-estradiol.

Research using rodent models has established a relationship between the steroid hormone estrogen and dopamine function, by revealing changes throughout the estrous cycle and by directly manipulating neuroendocrine signaling through ovariectomy and administration of estrogen. However, a direct link between estrogen levels and dopamine signaling had not been established in humans. The goal of this study, therefore, was to assess the relationship between circulating 17ß-estradiol and dopamine signaling in the human brain by testing for a relationship between two proxies for these variables: peripheral 17ß-estradiol and striatal dopamine D2-type receptor availability, measured with [18F]fallypride and positron emission tomography (PET). Sixteen (23-45 years of age) women were tested on 2 days of the menstrual cycle estimated prospectively to occur during (a) the early follicular phase, when estrogen levels are near their nadir, and (b) the periovulatory phase, when estrogen levels peak. PET scans with [18F]fallypride were performed on these 2 days, and serum 17ß-estradiol was measured using radioimmunoassay. Dopamine D2-type receptor availability did not differ significantly in the whole striatum or the caudate, putamen, or accumbens subregions during the high-estrogen vs. the low-estrogen phases of the menstrual cycle. We conclude that circulating estrogen levels do not affect dopamine D2-type receptor availability in the human striatum although other indices of dopaminergic function may be affected.