Controlling thought and action : a perspective from khat users and cocaine users

Abstract

The mechanisms that control thought and action vary with the fluctuating and dynamic nature of both internal physiological states and external environmental constraints. Psychoactive drugs have the ability to alter mood state or behavior by acting directly on these mechanisms. The alteration of cognitive processes is a core deficit in drug abuse that leads to a failure in regulating behavior. This thesis investigates whether the abuse of stimulant drugs like khat or cocaine somehow impact the processes that coordinate and combine information from different cognitive systems: cognitive control. In addition, we review the behavioral and physiological effects of the natural psychomotor stimulants khat and the cathinone-derived designer drug mephedrone.