George F. Koob’s research while affiliated with National Institutes of Health and other places

Since the last edition of the Handbook of Food and Addiction, published in 2012, research on this topic has progressed in many ways. Evidence is growing that certain foods, particularly highly processed foods with high levels of refined carbohydrates and/or added fats, can trigger addictive processes. Ultra-processed versions of these products may be even more addictive given the addition of flavor enhancers and additives that can make them intensely palatable, and are inexpensive, accessible, and highly convenient. In this edition, top researchers discuss groundbreaking science across biological, psychological, social, and policy domains that probe the role of addictive mechanisms in food intake and health. Future research questions are highlighted, including the impact of addictive foods on children, the role of the gut microbiome, the contribution of food insecurity, and the development of novel interventions to address the addictive impact of food. Potential policy and legal approaches are considered based on available science.

The cyclic adenosine monophosphate (cAMP) cascade is thought to play an important role in regulating alcohol-dependent behaviors, with potentially opposite effects following acute versus chronic administration. Phosphodiesterase 4 (PDE4) is the primary brain enzyme that metabolizes cAMP, thereby terminating its signal. Radioligand binding to PDE4 serves as an indirect biomarker of cAMP activity, as cAMP-protein kinase A (PKA)-mediated phosphorylation of PDE4 increases its affinity for radioligand binding ~10-fold. Of the four PDE4 subtypes, PDE4B polymorphisms are known to be strongly associated with alcohol and substance use disorders. This study imaged rats with the PDE4B-preferring positron emission tomography (PET) radioligand [ ¹⁸ F]PF-06445974 following acute and chronic ethanol administration, aiming to explore the potential of PDE4B PET imaging for future human studies. Compared to the control group treated with saline, acute alcohol administration (i.p. ethanol 0.5 g/kg) significantly increased whole brain uptake of [ ¹⁸ F]PF-06445974 as early as 30 minutes post-exposure. This effect persisted at 2 hours, peaked at 4 hours, and diminished at 6 hours and 24 hours post-exposure. In contrast, in a rat model of alcohol dependence, [ ¹⁸ F]PF-06445974 brain uptake was significantly reduced at 5 hours post-exposure and was normalized by 3 days. This reduction may reflect long-term adaptation to repeated alcohol-induced activation of cAMP signaling with chronic exposure. Taken together, the results suggest that PET imaging of PDE4B in individuals with alcohol use disorder (AUD) should be considered in conjunction with ongoing trials of PDE4 inhibitors to treat alcohol withdrawal and reduce alcohol consumption.

Alcohol use disorder (AUD) and binge drinking are highly prevalent public health issues. The stomach-derived peptide ghrelin, and its receptor, the growth hormone secretagogue receptor (GHSR), both of which are expressed in the brain and periphery, are implicated in alcohol-related outcomes. We previously found that systemic and central administration of GHSR antagonists reduced binge-like alcohol drinking, whereas a ghrelin vaccine did not. Thus, we hypothesized that central GHSR drives binge-like alcohol drinking independently of peripheral ghrelin. To investigate this hypothesis, we antagonized β1-adrenergic receptors (β1ARs), which are required for peripheral ghrelin release, and combined them with GHSR blockers. We found that both systemic β1AR antagonism with atenolol (peripherally restricted) and metoprolol (brain permeable) robustly decreased plasma ghrelin levels. Also, ICV administration of atenolol had no effect on peripheral endogenous ghrelin levels. However, only metoprolol, but not atenolol, decreased binge-like alcohol drinking. The β1AR antagonism also did not prevent the effects of the GHSR blockers JMV2959 and PF-5190457 in decreasing binge-like alcohol drinking. These results suggest that the GHSR rather than peripheral endogenous ghrelin is involved in binge-like alcohol drinking. Thus, GHSRs and β1ARs represent possible targets for therapeutic intervention for AUD, including the potential combination of drugs that target these two systems.

The Addictions Neuroclinical Assessment (ANA) is a neurobiologically-informed framework designed to understand the etiology and heterogeneity of Alcohol Use Disorder (AUD). Previous studies validated the three neurofunctional domains of ANA: Incentive Salience (IS), Negative Emotionality (NE) and Executive Function (EF) using secondary data. The present cross-sectional observational study assessed these domains in an independent, prospective clinical sample. Adults across the drinking spectrum (N = 300) completed the ANA battery, a standardized collection of behavioral tasks and self-report assessments. Factor analyses were used to identify latent factors underlying each domain. Associations between identified domain factors were evaluated using structural equation models. Receiver operating characteristics analyses were used to determine factors with the strongest ability to classify individuals with problematic drinking and AUD. We found (1) two factors underlie the IS domain: alcohol motivation and alcohol insensitivity. (2) Three factors were identified for the NE domain: internalizing, externalizing, and psychological strength. (3) Five factors were found for the EF domain: inhibitory control, working memory, rumination, interoception, and impulsivity. (4) These ten factors showed varying degrees of cross-correlations, with alcohol motivation, internalizing, and impulsivity exhibiting the strongest correlations. (5) Alcohol motivation, alcohol insensitivity, and impulsivity showed the greatest ability in classifying individuals with problematic drinking and AUD. Thus, the present study identified unique factors underlying each ANA domain assessed using a standardized assessment battery. These results revealed additional dimensionality to the ANA domains, bringing together different constructs from the field into a single cohesive framework and advancing the field of addiction phenotyping. Future work will focus on identifying neurobiological correlates and identifying AUD subtypes based on these factors.

The human brain undergoes rapid development during the first years of life. Beginning in utero, a wide array of biological, social, and environmental factors can have lasting impacts on brain structure and function. To understand how prenatal and early life experiences alter neurodevelopmental trajectories and shape health outcomes, several NIH Institutes, Centers, and Offices collaborated to support and launch the HEALthy Brain and Child Development (HBCD) Study. The HBCD Study is a multi-site prospective longitudinal cohort study, that will examine human brain, cognitive, behavioral, social, and emotional development beginning prenatally and planned through early childhood. Influenced by the success of the ongoing Adolescent Brain Cognitive DevelopmentSM Study (ABCD Study®) and in partnership with the NIH Helping to End Addiction Long-term® Initiative, or NIH HEAL Initiative®, the HBCD Study aims to establish a diverse cohort of over 7000 pregnant participants to understand how early life experiences, including prenatal exposure to addictive substances and adverse social environments as well as their interactions with an individual’s genes, can affect neurodevelopmental trajectories and outcomes. Knowledge gained from the HBCD Study will help identify targets for early interventions and inform policies that promote resilience and mitigate the neurodevelopmental effects of adverse childhood experiences and environments.