The Impact of Methadone Maintenance Therapy on Food Reward Processing in Opioid Dependence

Methadone maintenance therapy (MMT) has shown clear efficacy for relieving opioid withdrawal symptoms and reducing the morbidity and mortality of opioid dependence. A notable phenomenon associated with MMT is increased food intake, enhanced sweet preferences, and weight gain. The underlying neural mechanisms for opioid-related overconsumption are not well understood but are thought to arise from role in 1) increasing the palatability and hedonic aspects of food and 2) diminishing satiety signaling systems. In the proposed project, the investigators will examine methadone's potential role in opioid-related overconsumption of food. The investigators propose to examine eating behavior, sucrose preferences, and an event-related potential (ERP) component that is induced by appetitive motivation for highly rewarding foods in patients with a history of opioid dependence receiving methadone maintenance therapy (O+MMT) and not receiving opioid agonist therapy (O-MMT). A matched sample of obese and overweight adults without history of opioid use (HOC) will also be examined. Specifically, group differences in food intake and eating behaviors in the O+MMT group relative to individuals in the O-MMT and HOC group will be examined. Individuals will complete 24-hour dietary food recalls and inventories to characterize eating behavior and food addiction. Participants will complete psychophysical measures of chemosensory functioning of sucrose preference and pleasantness and identification ratings for odors varying in participants' hedonic characteristics. Individuals will also complete validated computer tasks to assess food preferences. Differences in cortical ERPs for high-reward food relative to low-reward food and non-food items will be examined. Event-related potentials will be recorded as participants view photos of rewarding and non-rewarding food items, as well as non-food items. ERP components that index sustained attentional engagement will be measured and compared.

Inclusion criteria

• English-speaking individuals
• Must be between 18 and 60 years of age
• For the O+MMT group, participants must be receiving MMT for at least 3 months
• For the O-MMT group, participants must have concluded their MMT (if applicable) at least three months prior to the date of the screening visit.

Exclusion criteria

• Individuals may not have a history of major neurological disorders
• No unstable medical issues that would affect appetite or blood glucose
• No pervasive developmental disorder or intellectual disability
• No significant visual/auditory impairment
• No history or current episode of psychosis
• No current opioid abuse
• No current antipsychotic medication use
• No major conditions that affect chemosensory function (e.g., history of nasal fracture or respiratory infection)
• Individuals with contraindication for the EEG will be excluded
• Individuals who are current pregnant or breastfeeding will not be enrolled
• For HOC, individuals with history of opioid dependence or current or past psychiatric disorders will be excluded