Methadone blunts emotional reactions
MedWire News: Opioid addicts receiving methadone maintenance therapy are less reactive to emotional stimuli than nonaddict controls, shows research.
According to Steven Savvas, at the University of Adelaide in South Australia, and colleagues, "emotional reactivity [is] defined as the change in emotional intensity upon presentation of an emotionally salient stimulus."
There has been little research in terms of the effect of opioids on emotional reactivity in humans, they say.
In this study, published in the journal Addiction, Velten's mood induction procedure was used to induce brief periods of elation or depression in the participants, in response to a set of self-referent statements.
The 21 opioid-dependent participants' mood responses were tested at times that corresponded with troughs and peaks in their plasma methadone concentrations. These were compared with results from 21 controls with no history of opioid dependence; both groups of participants were made up of 14 men and seven women, but the methadone group was significantly older than the control group (36.9 vs 26.9 years).
The average daily dose of methadone was 68.8 mg and, according to the Beck's Depression Inventory (BDI), the severity of depression in the methadone group was 15.3, where a BDI score of 11-16 corresponds to "mild mood disturbance."
At the trough time-point, the methadone and control groups showed similar elation (13.2 vs 14.2) and depression (23.6 vs 25.1) reactivity scores, which were measured using two 100-mm mood visual analog scales.
At the point of peak concentration in the methadone group, 3 hours after dose, depression reactivity was significantly lower in the methadone users compared with the controls (18.5 vs 36.7), as was elation reactivity (4.4 vs 19.0).
"This research suggests that methadone may blunt emotional reactivity following an increase in plasma methadone concentration," write Savvas and co-workers.
They suggest that their findings have "important implications for the psychological functioning of people exposed to opioids" because of the "growing consensus that emotion suppression is associated with worsened psychopathology."
Although it is not possible to tell whether these effects are typical of all opioids, the researchers suggest that, if opioids in general are found to decrease negative emotional responses, this might explain some of the motivation for use. They say this would correspond with anecdotal reports from users, which suggest they use them to cope with emotionally painful experiences.
By Chloe McIvor