The following is a summary of “Reduced neural functional connectivity during working memory performance in methamphetamine use disorder,” published in the February 2023 issue of Drug and Alcohol Dependence by Nestor et al.

Methamphetamine misuse is a rapidly increasing contributor to illness and death globally and is recognized as a significant public health concern in the form of Methamphetamine Use Disorder (MUD). Patients with MUD usually seek treatment during the early stages of abstinence when they experience cognitive impairments that can hinder their participation in treatment and rehabilitation. Cognitive impairments, specifically those about executive functions, indicate neural dysfunction affecting various brain regions and circuits. To expand our understanding of this field, we conducted a study comparing a group of individuals experiencing MUD (consisting of 30 participants in early abstinence, ranging from 3-11 days abstinent) with a healthy control group (consisting of 33 participants) in terms of brain activation, network connectivity, and topology. This was accomplished through functional magnetic resonance imaging (fMRI) while the participants performed an N-back working memory task. 

The N-back task entails the retention and manipulation of data in the transient memory and activates various neural mechanisms associated with executive functioning. The assessment was conducted at two levels of working memory complexity, namely 1-back and 2-back. In contrast to the HC cohort, the MUD cohort exhibited inferior task performance yet no fundamental distinctions in task-associated neural activation. The results of network-based statistical analyses indicate that the group diagnosed with Mild Cognitive Impairment (MUD) exhibited reduced functional network connectivity compared to the Healthy Control (HC) group during both difficulty loads of the N-back task. Further analyses based on graph theory revealed that the MUD group exhibited longer path lengths, lower clustering, and disrupted small-world properties in their networks. The findings indicate a disconnection in the functioning of neural networks that could be responsible for cognitive impairments observed in individuals with MUD during the initial abstinence phase.

Source: sciencedirect.com/science/article/pii/S0376871623000029