A small 2026 study found structural brain differences and poorer performance on selected planning measures in early methamphetamine abstinence. Other measures were nonsignificant, and inconsistencies within the report require restraint when quoting detailed numbers.
Bristow and colleagues studied 13 participants with methamphetamine use disorder in early abstinence and 14 controls. Participants underwent structural and myelin-sensitive MRI and completed the Tower of London planning task. This was an observational human comparison, not controlled methamphetamine administration.
MRI measurements addressed brain structure and myelin-sensitive signals. They did not measure methamphetamine in a biological specimen or establish the drug concentration present when participants completed the task.
The report identified longer execution times for correct solutions, more attempts and fewer correct solutions on the first attempt in the clinical group. Other indices, including total score and first-move timing, did not differ significantly. Imaging analyses identified regional cortical thickness and volume differences, while group differences in myelin measures were not demonstrated.
These results should not be reduced to either universal impairment or normal performance. The conclusions depend on which outcome is being considered, and nonsignificant myelin findings do not prove an absence of white-matter pathology.
The article contains inconsistencies between its narrative and tables, including descriptions of abstinence or use duration and whether total attempts differed significantly. Its cognitive table supports a significant total-attempt comparison, while one sentence describes that measure as nonsignificant. These inconsistencies limit confident quotation of the disputed details.
They do not erase the entire study, but they make it inappropriate to present every reported value as a settled measurement without clarification.
The groups differed in education, and the clinical group had more reported head injury and other potentially relevant exposures. The authors acknowledged small sample size, self-reported comorbidities and unmeasured factors including sleep and socioeconomic circumstances.
The study therefore cannot identify a specific cause of one person’s planning difficulty or diagnose acute impairment from MRI. Compare the separate interpretive problem in our discussion of putamen volume and cognition.