Striatal dopamine D2-like receptors availability in obesity and its modulation by bariatric surgery: a systematic review and meta-analysis

Abstract

There is significant evidence linking a ‘reward deficiency syndrome’ (RDS), comprising decreased availability of striatal dopamine D2-like receptors (DD2lR) and addiction-like behaviors underlying substance use disorders and obesity. Regarding obesity, a systematic review of the literature with a meta-analysis of such data is lacking. Following a systematic review of the literature, we performed random-effects meta-analyses to determine group differences in case–control studies comparing DD2lR between individuals with obesity and non-obese controls and prospective studies of pre- to post-bariatric surgery DD2lR changes. Cohen's d was used to measure effect size. Additionally, we explored factors potentially associated with group differences in DD2lR availability, such as obesity severity, using univariate meta-regression. In a meta-analysis including positron emission tomography (PET) and single-photon emission computed tomography (SPECT) studies, striatal DD2lR availability did not significantly differ between obesity and controls. However, in studies comprising patients with class III obesity or higher, group differences were significant, favoring lower DD2lR availability in the obesity group. This effect of obesity severity was corroborated by meta-regressions showing inverse associations between the body mass index (BMI) of the obesity group and DD2lR availability. Post-bariatric changes in DD2lR availability were not found, although a limited number of studies were included in this meta-analysis. These results support lower DD2lR in higher classes of obesity which is a more targeted population to explore unanswered questions regarding the RDS.

How images of food become cravingly salient in obesity

“…Furthermore, mesoaccumbens hypo‐connectivity in addiction was found to be inversely associated with years of cocaine use [39] and the severity of internet addiction [35], suggesting that altered mesoaccumbens connectivity may be evident in more severe cases of obesity (on average, our sample of patients were in the mild‐to‐moderate range of the obesity spectrum: average BMI = 36 kg/m 2 , comprising obesity class I and II) or in patients with obesity showing severe addiction‐like symptoms. Supporting this interpretation, a recent meta‐analysis of dopamine availability studies in obesity showed that only severe cases of obesity (class III or higher) display a significant reduction in dopamine availability in the striatum, whereas mild to moderate obesity (class I and II) do not [41].…”

Genetic Correlates as a Predictor of Bariatric Surgery Outcomes after 1 Year

“…We speculate that the surgical intervention directly modulated the dopaminergic reward system. It is known that D2 availability can decrease with overstimulation from overeating [105][106][107] and D2 striatal receptor availability is significantly decreased in cases of severe obesity [28]. These results suggest that surgery bypassed D2 super sensitivity and decreased the wanting mechanism in these obese patients.…”

“…The A1 risk allele is associated with various substance and nonsubstance addictions [70,94,95]. Carriers of this risk allele show a decreased availability of dopamine D2 receptors [96,97], which can result in D2 receptor super-sensitivity [98], increasing severity of alcoholism [99,100], obesity [28], and addiction relapse [98].…”

“…One challenge in weight management science is that most treatments for obesity are considered unsustainable over time [27,28]. Bariatric surgery is considered an optimal weight loss method for individuals unable to achieve efficient results from typical, nonsurgical weight loss interventions [29].…”

Portuguese observational cross-sectional clinical imaging study protocol to investigate central dopaminergic mechanisms of successful weight loss through bariatric surgery

“…These values were set based on a meta-analysis performed to investigate group differences in case–control studies comparing the same central dopamine receptors between individuals with obesity and non-obese controls. 36 In the case of significant differences, the overall Cohen’s d was −1.16 0.71.…”