No significant elevation of translocator protein binding in the brains of recently abstinent methamphetamine users. (1st August 2020)

• Record Type: Journal Article
• Authors: London, Edythe D.; Okita, Kyoji; Kinney, Kaitlin R.; Dean, Andrew C.; McClintick, Megan N.; Rizor, Elizabeth J.; Johnson, Maritza C.; Mahmoudie, Tarannom; Brody, Arthur L.; Nurmi, Erika L.; Seaman, Lauren C.; Farahi, Judah; Ginder, Nathaniel; Mandelkern, Mark A.
• Is Part Of: Drug and alcohol dependence. Volume 213(2020)
• Publication Date: 2020-08-01
• Subjects: Neuroinflammation -- Brain imaging -- Methamphetamine -- Stimulants -- Translocator protein -- Positron emission tomography; Drug abuse -- Periodicals; Alcoholism -- Periodicals; 616.86
• DOI: 10.1016/j.drugalcdep.2020.108104
• Languages: English
• ISSNs: 0376-8716

Abstract

Highlights: Methamphetamine (MA) users in early abstinence showed typical characteristics. TSPO binding in the brain did not differ significantly in MA users vs. controls. The findings differ from a prior report on MA users who were > 6 months abstinent. Abstract: Background: Radioligands for the translocator protein (TSPO) 18 kDa have been used with positron emission tomography (PET) to assess neuroinflammation and microglial activation in psychiatric disorders. One study using this approach showed substantial TSPO elevation throughout the brain in chronic methamphetamine users following long-term abstinence (0.5–4 years), but clients typically present for treatment earlier in abstinence. Methods: We used PET with [ 11 C]DAA1106 to compare standardized uptake values (SUVs) as an index of TSPO binding in the brains of methamphetamine-dependent participants who were abstinent for < 6 months (n = 11) and healthy controls (n = 12). We also assayed other typical correlates of Methamphetamine Dependence (e.g., striatal D2-type dopamine receptor deficits, depressed mood, anxiety and impaired emotion regulation). Results: Methamphetamine users exhibited depression (p < 0.0001), anxiety (p = 0.002), difficulties in emotional regulation (p = 0.01), and lower striatal dopamine D2-type receptor availability vs. controls (p = 0.02). SUVs for [ 11 C]DAA1106 were larger in all brain regions of methamphetamine-dependent participants vs. controls, but the effect size was small to medium and not statistically significant. Conclusions: The discrepancy between the lack of significant difference in TSPO binding in early-abstinent methamphetamine users vs. controls in this study and a previous report of elevated binding in longer-abstinent methamphetamine users may reflect methodological differences or limitations of TSPO binding as an index of neuroinflammation. It also seems possible that gliosis increases over time during the first 6 months of abstinence; longitudinal studies could clarify this possibility.