Background. This protocol is a collaboration between NIDA's Archway Clinic and the Johns Hopkins School of Public Health (JHSPH). The collaboration arose in response to NIH's Genes and Environment Initiative (GEI). There is no genetic component to this protocol; rather, the goal is to develop field-deployable measures of environmental influences (stressors, drug exposure, etc.) that can ultimately be used in studies of gene-environment interactions.

Objective. To use Palm Pilots (PDAs) to measure stress and drug use and Global Positioning System (GPS) units to assess geographical location. In a future arm of the protocol (upon IRB approval), we intend to add ambulatory monitoring of heart rate and physical activity to assess physiological responses to stress in real time.

Participant population. Opioid-dependent outpatient adults (up to 200 enrolled; up to 150 completers). Target enrollment will include 40% women and 60% minorities (mostly African-American).

Experimental design. A natural-history study of stress (both personal and environmental) and drug use.

Methods. Participants will undergo 18 weeks of daily methadone maintenance and will be offered at least 10 weeks of methadone taper (weeks 19-28). To track drug use, stress, and geographical location (a measure of environmental risk), each participant will carry a PDA and a GPS unit for 16 of the 18 weeks. Event-triggered entries will be initiated by participants (1) each time that they use a drug and (2) each time they feel overwhelmed, anxious, or stressed more than usual. Participants will also make 3 random-signal-triggered recordings per day and one brief end of day recording. We will compare EMA results with more traditional assessments of drug use and stress: (1) urine will be collected three times weekly, (2) retrospective self-report questionnaires on drug use and stress will be given regularly, and (3) a laboratory session examining responsiveness to standardized stressors will occur both early and late in treatment. In this session, there will also be blood draws and anthropometric measurements to assess allostatic load (a physiological marker of long-term cumulative stress). After 18 weeks of methadone maintenance, participants will discontinue carrying the PDA and GPS unit and will have the choice of transferring to a community clinic or undergoing a ten-week taper from methadone at the Archway clinic.

Primary outcome measures: (1) EMA reports of drug use and psychosocial stress, and (2) real-time assessment of environmental risk exposure as measured via integration of GPS data with the Neighborhood Psychosocial Index.