The catatonia conundrum: evidence of psychomotor phenomena as a symptom dimension in psychotic disorders.

To provide a rational basis for reconceptualizing catatonia in Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition), we briefly review historical sources, the psychopathology of catatonia, and the relevance of catatonic schizophrenia in contemporary practice and research. In contrast to Kahlbaum, Kraepelin and others (Jaspers, Kleist, and Schneider) recognized the prevalence of motor symptoms in diverse psychiatric disorders but concluded that the unique pattern and persistence of certain psychomotor phenomena defined a "catatonic" subtype of schizophrenia, based on intensive long-term studies. The enduring controversy and confusion that ensued underscores the fact that the main problem with catatonia is not just its place in Diagnostic and Statistical Manual of Mental Disorders but rather its lack of conceptual clarity. There still are no accepted principles on what makes a symptom catatonic and no consensus on which signs and symptoms constitute a catatonic syndrome. The resulting heterogeneity is reflected in treatment studies that show that stuporous catatonia in any acute disorder responds to benzodiazepines or electroconvulsive therapy, whereas catatonia in the context of chronic schizophrenia is phenomenologically different and less responsive to either modality. Although psychomotor phenomena are an intrinsic feature of acute and especially chronic schizophrenia, they are insufficiently recognized in practice and research but may have significant implications for treatment outcome and neurobiological studies. While devising a separate category of catatonia as a nonspecific syndrome has heuristic value, it may be equally if not more important to re-examine the psychopathological basis for defining psychomotor symptoms as catatonic and to re-establish psychomotor phenomena as a fundamental symptom dimension or criterion for both psychotic and mood disorders.