Methylxanthines and drug dependence: interactions and toxicity

This chapter describes the psychostimulant actions of methylxanthines and discusses the possible occurrence of dependence toward these substances. Moreover, the chapter examines the interactions between methylxanthines and other psychoactive drugs, in consideration of the fact that methylxanthines are extensively consumed by the general population, often in combination with other psychoactive substances. These methylxanthine–drug interactions are discussed in terms of both drug dependence and toxicity. Since caffeine is the methylxanthine that has the most marked effects on mental processes and is also the most widely studied substance in this class, the chapter will pay particular attention to caffeine by describing its psychostimulant and behavioral effects and discussing the potential consequences of its excessive consumption.