Understanding Drugs and Behaviour

Chapter One

Overview

Psychoactive drug use is not just a phenomenon of the 20th century; many different types of drug have been used throughout recorded history. In this chapter we will outline the main classes of psychoactive drug. We are able to do this in a single chapter because, despite there being thousands of different drugs, they can be classified in a few main groups (Table 1.1). The crucial role of neurotransmitters will also be described because psychoactive drugs alter mood and behaviour by modifying nerve activity in various ways. Thus, a basic understanding of neurotransmitter actions is vital in order to understand how drugs can affect behaviour. Tolerance and addiction may also develop, when regular drug use causes long-term changes in neurotransmission activity. Next, we will emphasise that all drugs have a range of positive and negative behavioural effects. Positive or desirable effects, such as feelings of pleasure, are the reasons people take drugs. But drugs also cause negative effects, which is why drug taking can cause so many psychosocial problems.

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