The Continuum Hypothesis of Mood Disorders

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Sir: The recent (November 2007) article by Laursen et al. tested the continuum between mood and psychotic disorders.The authors state that, using "selected risk factors" (i.e., somefamily, environmental, and birth variables), "differences betweenthe phenotypes were quantitative rather than qualitative" but that differences between genders and between"age-specific incidences" favored instead the Kraepeliniandichotomy (between "manic-depressive insanity," includingmost DSM-IV-TR mood disorders, and "dementia praecox," includingseveral DSM-IV-TR psychotic disorders). The variableschosen are questionable. Among classic diagnostic validators, age at onset, boundaries between syndromes (i.e., bimodaldistribution of distinguishing features), course, psychometric(multivariate) analyses, and, most of all, psychiatric familyhistory (in this case, of bipolar, unipolar, psychotic disorders)figure prominently.’ ‹