Introduction

Since the rise of neuropsychological studies in brain-damaged patients, to the now current popularity of functional neuroimaging, neuroscientists have endeavoured to localize the elusive engram. Localizationist theories of cognitive function have now diminished, however, and neural network explanations are currently in vogue. Almost in parallel to this, an increasing interest in the influence of neurotransmitter systems on cognition has emerged. The study of the neurochemical modulation of memory has dominated the cognitive psychopharmacological literature, in both humans and animals, in recent years. Although this chapter does not provide an exhaustive review of this literature, it does introduce the reader to the more widely researched hypotheses concerning the modulation of this most enigmatic, yet most tangible, of cognitive processes. In addition, some pertinent data are included. While it is of obvious clinical import to treat memory dysfunction in patient populations, drugs which are shown to enhance memory in patients, healthy volunteers or experimental animals may additionally inform us as to the neurochemical basis of normal memory function.

Although the various manifestations of dementia are the most obvious form of clinical memory disorder (see Chapter 7, this volume), patients suffering from functional psychiatric disorders may also show signs of mnemonic dysfunction. This chapter will concentrate on drug treatments for dementia, since these have been the driving force behind the search for cognitive enhancers. For the more functional psychiatric disorders, such as depression and anxiety, psychoactive agents are generally used to treat the primary behavioural and affective symptoms, rather than any cognitive dysfunction.