Elevated oxytocin levels in intravenous diamorphine substitute patients: A look at the connection between heroin addiction and the search for good feelings

Introduction:

Based on the descriptions of a feeling of security during intravenous use of heroin, as well as the different co-morbidities, such as depression in heroin addicts, we have dealt in this study with the relationship between opiate dependence and oxytocin levels and depression. The aim of the study was to establish a possible association between consumption (both i.v. and oral substitutes) and effect on oxytocin levels and severity of depression (measured by BDI II).

Methods:

We conducted a prospective study, including two sub-groups of opiate-dependent patients. In one group we investigated 55 opiate-dependent patients recruited within a venue especially for opiate dependent patients. All patients in this subgroup were in levomethadone maintenance therapy. In the other sub-group we examined 28 outpatients of the Hannover Medical School, participating in the diamorphine maintenance program. Furthermore we included 51 age- and gender-matched, healthy controls. Controls did not suffer from any psychiatric disease or substance misuse. Blood samples were taken in patients and controls in the morning between 8 and 10 a.m. In the opiate dependent patients blood was taken two hours after intake of diamorphine or levomethadone. Sociodemographic data were assessed by a structured interview. All patients answered to a test battery, including the Beck's Depression Inventory (BDI-II).

Results:

There was a significant difference between the substituted groups compared to the controls at oxytocin levels. The mean value of the oxytocin levels of the polamidone substituted group was 134,234 (µlU/ml), of the diamorphine users 179,317 (µlU/ml) and of the controls only 64,357 (µlU/ml). The cross-group correlation of oxytocin and BDI-II was significant with a correlation coefficient of 0.411. 44% (R²= 0.44) of the variances in BDI-II can be attributed solely to the group membership of the test persons. 13% (R²= 0.13) of the influence of the group membership of the subjects on the BDI II values can be explained by the oxytocin level.

Conclusion:

We were able to demonstrate that the substituted patients had significantly elevated oxytocin levels compared to the controls. Significant values were also found in the groups on depression testing. Our results also show a possible explanation with significant values that the oxytocin level is directly related to the BDI-II value across all groups. To discuss this has a special relevance with regard to the hypothesis of "self-medication" and possibly the longing for the "deep feeling of security".