Science, Medicine, and the Anesthesiologist

The subjective drug craving is the core driver of methamphetamine use disorder and its relapse rate. There are no reliable biomarkers of this, but it is possible that there are distinct brain functional connectivity patterns that indicate craving. Localized sources of brain activity can be derived from multichannel electroencephalography (EEG), and the “imaginary” coherence between these sources is an accepted measure of coupling between brain regions. Fourier transformation of the spectral density produces a “real” and “imaginary” part from which synchrony parameters can be calculated. The latter is felt to be more resistant to noise. The imaginary coherence between 31 brain regions-of-interest was calculated from 57 patients (mean ± SD age, =34.8 ± 7.2 yr) with methamphetamine use disorder, and 52 matched controls (36.6 ± 10.0 yr). After exposure to a video of methamphetamine use, visual analogue craving scores for each subject were obtained. There were significant correlations between craving scores and brain region coupling (mainly between the left posterior middle frontal gyrus and medial prefrontal cortex, r = 0.5, P = 0.03) for delta and beta frequency bands, but no correlations with standard spectral analysis. Using machine learning and testing on a second methamphetamine use disorder database (n = 44), the beta connectivity model had an 80.1% classification accuracy (sensitivity, 82.1%; specificity, 79.6%).

Take home message: These results suggest that functional connectivity between certain brain regions in the beta frequency range is a better indicator of methamphetamine use disorder than the simple EEG spectrum.