Disruption of regional homogeneity in the brains of chronic methamphetamine users.

Previous studies have reported evidence supporting structural and functional alterations in the brains of methamphetamine (MA) users. The aim of the present study was to extend current knowledge regarding brain function(s) in MA users by examining regional homogeneity (ReHo). Chronic MA users (51 male, 46 female), who were undergoing supervised abstinence for 12 to 621 days, and 79 healthy controls (43 male, 36 female) underwent resting-state functional brain magnetic resonance imaging. Voxel-wise whole-brain scale group differences in ReHo were examined. The mean ReHo values of significant clusters were extracted, and linear regression was used to identify factors that contributed to these mean ReHo values. MA users exhibited lower ReHo values in the left orbital part of the inferior frontal gyrus extending to the left insula and left temporal pole, left amygdala, and left fusiform gyrus. MA users also exhibited greater ReHo values in the bilateral pre- and postcentral gyri and right cerebellum. Characteristics of MA use, including duration, duration of abstinence from MA, and age at onset of MA use, demonstrated no reliable contribution to ReHo of the significant clusters. Findings of the present study demonstrated that chronic MA use was associated with regional specific disruption of ReHo, which is relatively independent of structural and functional alterations and, apparently, does not recover after relatively long-term abstinence. This disruption may underlie overall neurocognitive deficits in MA users, which is difficult to recover.

The relationship between duration of abstinence and gray-matter brain structure in chronic methamphetamine users.

Background: Brain structural findings in chronic methamphetamine users have been inconsistent. Identifying contributing influences (e.g., sex, abstinence duration) can help clarify the clinical course of recovery.Objectives: We studied the effects of long-term methamphetamine abstinence on gray-matter volume. Our hypothesis was that smaller volume early in abstinence would precede long-term recovery.Methods: Individuals who used methamphetamine (≥100 g lifetime use, mandated to residential treatment for methamphetamine-positive urine; 40 men, 21 women), undergoing supervised abstinence (men: 12-400 days; women: 130-594 days), were compared to healthy controls (49 men, 36 women) using T1-weighted MRI. Volumes of orbitofrontal, anterior cingulate and parietal cortex, hippocampus, and striatum were measured using Freesurfer software. Associations of volumes with abstinence duration were tested in males and females separately because their abstinence times differed (121.5 ± 124.5 vs. 348.0 ± 128.6 days, p < 0.001); only males were studied in early abstinence. The General Linear Model was used to test effects of abstinence duration and group (methamphetamine users vs. controls).Results: In males, duration of abstinence was multivariate significant for gray-matter volumes (p = 0.017). Abstinence duration was associated with increases in volumes of the orbitofrontal and parietal cortices (ps = 0.031, 0.016) and hippocampi (ps = 0.044). Irrespective of abstinence, male methamphetamine users had smaller hippocampi than male controls (p = 0.008). Females showed no significant effects of group or abstinence.Conclusions: In males, abstinence from methamphetamine appears to result in volumetric increases in regions important for cognitive function, which may affect recovery during the course of treatment. Data from the period of early abstinence are required to evaluate volumetric changes in females.

Gray-matter structure in long-term abstinent methamphetamine users.

BACKGROUND: Previous studies of brain structure in methamphetamine users have yielded inconsistent findings, possibly reflecting small sample size and inconsistencies in duration of methamphetamine abstinence as well as sampling and analyses methods. Here we report on a relatively large sample of abstinent methamphetamine users at various stages of long-term abstinence. METHODS: Chronic methamphetamine users (n = 99), abstinent from the drug ranging from 12 to 621 days, and healthy controls (n = 86) received T1-weighted structural magnetic resonance imaging brain scans. Subcortical and cortical gray-matter volumes and cortical thickness were measured and the effects of group, duration of abstinence, duration of methamphetamine use and onset age of methamphetamine use were investigated using the Freesurfer software package. RESULTS: Methamphetamine users did not differ from controls in gray-matter volumes, except for a cluster in the right lateral occipital cortex where gray-matter volume was smaller, and for regions mainly in the bilateral superior frontal gyrui where thickness was greater. Duration of abstinence correlated positively with gray-matter volumes in whole brain, bilateral accumbens nuclei and insulae clusters, and right hippocampus; and with thickness in a right insula cluster. Duration of methamphetamine use correlated negatively with gray-matter volume and cortical thickness of a cluster in the right lingual and pericalcarine cortex. CONCLUSIONS: Chronic methamphetamine use induces hard-to-recover cortical thickening in bilateral superior frontal gyri and recoverable volumetric reduction in right hippocampus, bilateral accumbens nuclei and bilateral cortical regions around insulae. These alternations might contribute to methamphetamine-induced neurocognitive disfunctions and reflect a regional specific response of the brain to methamphetamine.

Factors affecting the occurrence of psychotic symptoms in chronic methamphetamine users.

Studies of risk for psychotic symptoms in methamphetamine users have focused primarily on drug use immediately before symptoms had appeared. Here we assessed factors reflecting characteristics of lifetime methamphetamine use before the appearance of psychotic symptoms. Four hundred ninety-five methamphetamine users (322 men, 173 women) were studied with consideration of the following features of methamphetamine use: age of initiation, maximum single dose, number of uses at or near the maximum dose, longest period of daily use, average dosage during that period, number of heavy use periods, and number of sustained abstinence periods (>1 month). Use of drugs other than methamphetamine and family history of schizophrenia were also considered. Retrospective self-reports of psychotic symptoms were obtained on the Brief Psychiatric Rating Scale. Factors associated with the occurrence of initial psychotic symptom(s) were identified using logistic regression. Later age of initiation, more uses at maximal or near maximal dosage, and more periods of prolonged abstinence were identified as protective factors. We conclude that early methamphetamine use can promote psychotic symptoms, possibly by altering neurodevelopment, whereas long abstinence periods may protect by allowing recovery. Negative associations of the appearance of psychotic symptom(s) with frequent high-dose administration suggest protection through tolerance.