Prefrontal GABA and glutamate levels correlate with impulsivity and cognitive function of prescription opioid addicts: A 1H‐magnetic resonance spectroscopy study

• Published in: Psychiatry and clinical neurosciences 2020-01, Vol.74 (1), p.77-83
• Main Authors: Li, Jian‐Neng, Liu, Xi‐Long, Li, Long
• Format: Article
• Language: English
• Subjects: Addictions; Addicts; Cerebrospinal fluid; Codeine; Cognitive ability; Cough; glutamate; Impulsive behavior; Impulsivity; Magnetic resonance spectroscopy; Metabolites; Narcotics; neuropsychology; Opioids; Prefrontal cortex; prescription opium dependence; Spectrum analysis; Syrups; γ-Aminobutyric acid
• ISSN: 1323-1316; 1440-1819
• DOI: 10.1111/pcn.12940

Aim Prescription opioids are psychoactive substances that can elicit many neuropsychological effects. There are no studies that directly demonstrate the effects of prescription opioid addiction (POA) on the human brain. This study aimed to quantify γ‐aminobutyric acid (GABA) and glutamate (Glu) levels in the prefrontal cortex (PFC) of POA patients using proton magnetic resonance spectroscopy (1H‐MRS), and to explore their association with impulsive behavior and cognitive impairment. Methods Thirty‐five patients with a definitive clinical diagnosis of codeine‐containing cough syrup dependence and 35 matched healthy controls underwent neuropsychological assessments, namely the Barratt Impulsiveness Scale (BIS‐11) and the Montreal Cognitive Assessment Scale (MoCA). Point‐resolved spectroscopy was performed to detect GABA and glutamate within the medial PFC, and the corresponding levels were estimated using jMRUI and corrected for fraction of cerebrospinal fluid in the 1H‐MRS voxel. The difference in metabolite levels between groups and the correlation between metabolite levels and psychometric scores in patients were analyzed statistically. Results The peak level predominantly consisting of GABA with a relatively small influence of other chemicals (GABA+) was lower and that of glutamate was higher in the PFC of POA patients than in healthy controls. GABA+ levels correlated negatively with BIS‐11 scores but correlated positively with MoCA scores. In contrast, glutamate levels showed a positive correlation with BIS‐11 scores but no significant correlation with MoCA scores. Conclusion The quantitative in vivo measurement of GABA and glutamate levels in the PFC by 1H‐MRS could be a reliable way to evaluate impulsivity and cognitive function of POA.