Developing Classification in Psychiatry - Implications of 50 Years of Progress in Psychopharmacological Therapeutics
Developing Classification in Psychiatry - Implications of 50 Years of Progress in Psychopharmacological Therapeutics
Forty years ago, after a spate of pharmacological discoveries, diagnostic confidence was rising in psychiatry. Textbooks of the time indicated that the work of Pinel, Kraepelin and Bleuler had laid the foundation for imminent and encouraging progress in clarifying the connections between aetiology (or at least pathogenesis), classificatory (diagnostic) labels and largely pharmacologically based therapeutic choices.1 This could be seen within the framework of ‘natural’ and ‘categorical’ classifications as clarified by Pichot.2 He considered that, in science, the ‘natural’ classifications were those that allow the maximum number of predictions.
With the criteria set out by Robins and Guze,3 psychiatry felt confident of validating its diagnostic groupings and refining the relationship between, for example, schizophrenia and neuroleptics; depression and antidepressants; bipolar disorders and lithium; anxiety and anxiolytics; and anorexia nervosa and family therapy, i.e. diagnoses predicting treatment. The missing links in the understanding of both classifications and therapies were expected to be filled in with all of the promising developing research, particularly with better clinical, cohort and other longitudinal studies, neurobiological developments and psychopharmacological fine-tuning.
Antipsychotics and the Treatment of Psychiatric Disorders
The introduction of chlorpromazine in the 1950s and the subsequent development of other related phenothiazines, now referred to as conventional antipsychotics, provided a resurgence of interest in the pathogenesis and treatment of psychiatric disorders, particularly schizophrenia. Knowledge of the actions of such agents has significantly stimulated research in biological psychiatry aimed at defining patho-physiological abnormalities. The discovery of dopaminergic receptor-blocking capabilities of conventional antipsychotic drugs led to the dopamine hypothesis of schizophrenia.4 Conventional anti-psychotics were found to be effective in controlling psychotic symptoms, such as hallucinations, delusions and agitation, and in reducing both morbidity and mortality. However, they have significant side effects, such as extrapyramidal symptoms. Atypical antipsychotics were introduced in the last two decades and have led to dramatic shifts in the treatment of major mental illness. They offer physicians the ability to treat patients with schizophrenia and bipolar/mania with less of the adverse effects of the conventional antipsychotics. This is because they have affinity for the serotonergic neurotransmitter system in addition to their effects on the dopamine D2 receptor. This affinity may explain their clinical profile of lower extrapyramidal symptoms and improvement in cognition.5 On account of this, adherence to treatment is enhanced. Atypical antipsychotics – clozapine, risperidone, olanzapine, quetiapine, ziprasidone and aripiprazole – are being prescribed for schizophrenia, bipolar disorder and related psychoses at ever-increasing rates because of their beneficial side effect profiles and, in the case of clozapine, superior efficacy in treatment-resistant disorder. Several new formulations of atypical neuroleptics have become available, including liquid, orally disintegrating tablets and rapid-acting and long-acting intramuscular preparations.
However, in the last ten years, the links between diagnoses and pharmacology have become less clear, and the earlier optimism would appear to have been a little premature.
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