The influence of drugs upon testimony

A wide range of drugs (medicines) are used currently, many of which are designed to affect brain function. Others do so as a side-effect. The effects depend on how the body deals with the drug (pharmacokinetics) and how the drug affects the body, including the brain (pharmacodynamics). An extensive range of effects on the brain and psychological functioning can ensue, including effects on intellectual functioning, dexterity, memory, learning and subjective effects. Individual factors are important and can profoundly influence both the type and extent of drug effects. Relevant drugs can be divided into: 1. Those prescribed primarily to treat psychiatric disorders. These include sleeping tablets, tranquillizers, antidepressants and antipsychotics. 2. Those used to treat neurological disorders that have psychological side-effects. Examples are anticonvulsants and anti-parkinsonian drugs. 3. Those used to treat non-nervous disorders that may have psychological side-effects. 4. Illicit drugs used in the non-medical context by drug addicts. Drug-induced states that can influence testimony are mainly sedation, disinhibition, paradoxical reactions and alterations in memory. A list of pointers was given in this paper with respect to practical considerations in assessing the possible effects of drugs on testimony.