044-22 – Long-term Effects of Illicit Stimulant Use on Cognitive Function and Cortical Haemodynamics

Stimulants such as MDMA, cocaine, amphetamines and their analogues are among the most commonly used illicit substances in Europe, and poly-drug use is highly prevalent among users. It is therefore important to understand how they impact performance and underlying brain function. Previous studies show impairments in executive functions linked to impaired dopamine and serotonin transmission, neuroinflammation and neurotoxicity. This study will use the Stop-Signal, Letter memory and Number letter tasks to assess response inhibition, switching, and updating respectively, and functional near infrared spectroscopy (fNIRS) to analyse underlying brain activation. We expect to find substance-dependent impairments in executive functioning with extent and subcomponent variability among users. Regardless of performance, we anticipate increased oxygenated and deoxygenated haemoglobin levels in the prefrontal cortex reflecting higher mental effort in all subcomponents.