Time series modeling of heroin and morphine drug action.

RATIONALE: Clinical observations and recent findings suggested different acceptance of morphine and heroin by intravenous drug users in opiate maintenance programs. We postulated that this is caused by differences in the perceived effects of these drugs, especially how desired and adverse effects of both drugs interacted. OBJECTIVES: We measured the desired and adverse effects of high doses of injected morphine and heroin in patients to determine the causal interactions between both types of effects and test the hypothesis of a differential mechanism of action. METHODS: Thirty-three patients (five females, 28 males; mean duration of previous street heroin use 10.7 years, mean age 30.1 years) were randomly allocated double-blind to the substance groups. The average daily dose per participant in the heroin condition (n=17) was 491 mg, in the morphine condition (n=16) 597 mg. The observation period lasted 3 weeks; an average of 70 injections was received. After each injection of either substance, various aspects of drug effects were recorded systematically. Ratings were summarized into the factors "euphoria" and "adverse effects". Time series models were computed for each participant on the basis of the factor scores, using vector autoregression (VAR). RESULTS: A highly significant difference between the substances was found in the interaction between "euphoria" and "adverse effects". Adverse effects of heroin preceded higher euphoria, whereas adverse effects of morphine preceded subsequent lower euphoria. Additionally, the finding of a higher level of adverse effects in morphine was replicated. CONCLUSIONS: Results point to different mechanisms of action of the two opioids when the perceived drug effects are evaluated in a field setting. This may explain the better acceptance of heroin in opiate-assisted treatment of intravenous drug patients. The method used can be a valuable tool for the comparison of substance groups other than opioids.

Analysis of crisis intervention processes.

The remediation processes in psychosocial crisis intervention were modeled focusing on cognitive orientation. Frequent observations and subsequent process modeling constitute a novel approach to process research and reveal process-outcome associations. A sample of 40 inpatients who were assigned to treatment in a crisis intervention unit was monitored in order to study the process of crisis intervention. The process data consisted of patients' self-ratings of the variables mood, tension, and cognitive orientation, which were assessed three times a day throughout hospitalization (M = 22.6 days). Linear time series models (vector autoregression) of the process data were computed to describe the prototypical dynamic patterns of the sample. Additionally, the outcome of crisis intervention was evaluated by pre-post questionnaires. Linear trends were found pointing to an improvement of mood, a reduction of tension, and an increase of outward cognitive orientation. Time series modeling showed that, on average, outward cognitive orientation preceded improved mood. The time series models partially predicted the treatment effect, notably the outcome domain "reduction of social anxiety," yet did not predict the domain of symptom reduction. In conclusion, crisis intervention should focus on having patients increasingly engage in outward cognitive orientation in order to stabilize mood, reduce anxiety, and activate their resources.