Estimates of the prevalence of bipolar affective disorder. Methods based on treatment with lithium

During this century the epidemiology of the affective disorders has been studied, several classifications have been described and effective treatment measures have been introduced. Difficulties have been encountered in the epidemiology area due to inconsistent use of the terminology of measurement and varying types of classification; although it is possible to arrive at a broad consensus of agreement if the data are examined restrictedly. The clinical need for accurate rates of illness has become greater since the inception of the prophylactic drug lithium carbonate. While not used specifically for bipolar affective disorder, it is only for this disorder that its use has been demonstrated beyond doubt. The occurrence of mania in this disorder enables this aspect of the condition to be used as a marker. This paper describes three measures of the period prevalence of bipolar affective disorder, based upon treatment with lithium, two of which are of the "unobtrusive' type. Agreement was found between the three approaches and the utility of these for general use is discussed.