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Cingulate biochemistry in heroin users on substitution pharmacotherapy
Antonio Verdejo-García1, Dan I Lubman, Kim Roffel
11Melbourne Neuropsychiatry Centre, University of Melbourne, Melbourne, Australia.
The Australian and New Zealand Journal of Psychiatry
|October 13, 2012
Summary
High-dose methadone normalizes anterior cingulate cortex (ACC) biochemistry in opioid users, unlike buprenorphine. Elevated myo-inositol in buprenorphine users correlates with depression, suggesting differing neurobiological impacts.
Area of Science:
- Neuroscience
- Addiction Medicine
- Neuroimaging
Background:
- Opiate substitution pharmacotherapy (OSP) improves treatment retention and reduces illicit drug use, but its neurobiological underpinnings are unclear.
- Anterior cingulate cortex (ACC) dysfunction is linked to addiction severity and mood issues in opioid users.
- OSP may exert benefits by normalizing ACC function.
Purpose of the Study:
- To investigate the differential effects of methadone versus buprenorphine on dorsal ACC biochemistry.
- To explore the relationship between methadone/buprenorphine treatment, ACC biochemistry, and depressive symptoms.
Main Methods:
- Proton Magnetic Resonance Spectroscopy (1H-MRS) was used to assess dorsal ACC metabolite concentrations.
- Participants included heroin-dependent individuals on methadone (n=10) or buprenorphine (n=14), and 24 healthy controls.
- Measured metabolites included N-acetylaspartate (NAA), glutamate/glutamine (Glx), and myo-inositol (mI).
Main Results:
- Methadone treatment showed dose-dependent normalization of dorsal ACC biochemistry (increased NAA and Glx, decreased mI).
- Buprenorphine-treated individuals exhibited higher right dorsal ACC mI and Glx levels compared to methadone users.
- Elevated mI levels in buprenorphine users positively correlated with depressive symptoms.
Conclusions:
- High-dose methadone appears to have a beneficial effect on dorsal ACC biochemistry.
- Elevated myo-inositol levels may be linked to depressive symptoms in individuals treated with buprenorphine.
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