An abstinence study found lower local activity measures alongside stronger hippocampal connectivity in selected comparisons. These findings show why a single description such as globally increased or decreased brain activity can be misleading.
The final analysis included 25 male methamphetamine-abstinent patients and 29 controls. Researchers combined regional homogeneity, fractional low-frequency amplitude, seed-based connectivity and independent-component analyses with Montreal Cognitive Assessment scores.
Each metric describes a different feature of resting fMRI data. Local fluctuation amplitude, local synchronization and correlation between distant regions are related research measures, but they are not interchangeable estimates of total brain function.
The patient group showed reduced local measures in selected regions and enhanced connectivity involving the right hippocampus. Greater right hippocampus–inferior temporal connectivity was associated with better total cognitive screening scores within the patient group.
That positive association does not establish that the increased connection restored cognition or caused compensation. A group can show abnormal connectivity while variation within that group relates positively to performance. Those are separate comparisons with different reference points.
The analyses used metric-specific voxel thresholds and cluster-level correction. Their results should remain attached to those analysis choices. The cognitive assessment was a screening instrument, not a complete characterization of every cognitive domain.
The sample was small, male and cross-sectional. It cannot demonstrate recovery trajectories, establish causal injury or validate an individual diagnostic scan. No controlled methamphetamine dose was administered, and the signals were not drug concentrations. The study supports investigating multiple dimensions of network function rather than assigning a single activity label to abstinence.
See resting-network responses after controlled methamphetamine administration.
Multi-metric resting-state fMRI reveals brain network abnormalities underlying cognitive impairment in male patients during methamphetamine abstinence. doi:10.1186/s12888-026-08337-x.