Atypical Psychosis The Other Boundary of Bipolar Disorder

Tadafumi Kato1

The concept of bipolarity presented by Hagop Akiskal is a good clue for all psychiatrists to find an alternative and effective treatment strategy in patients who might have received a diagnosis of unipolar depression according to classical diagnostic systems. Since nothing should be added to his thorough and well-organized review, I would like to comment on one topic, the other boundary of bipolar disorder, which may be specific to Japan.

Although DSM-IV is generally used in research and education in Japan, many psychiatric experts are still influenced by traditional clinical diagnostic practice. In particular, the traditional diagnosis of "atypische Psychose" (atypical psychosis) still has some impact on clinical practice, especially in the Western part of Japan. The concept of atypical psychosis was proposed by Mitsuda [1] in Japan based on his hypothesis that there is a genetically different category between schizophrenia and manic-depressive illness. Its conceptual framework was subsequently established by Hatotani [2] in the 1960s. The Japanese concept of atypical psychoses focuses on the "alteration of consciousness" and the nosological relationship to epilepsy. This concept

1 Laboratory for Molecular Dynamics of Mental Disorders, Brain Science Institute, Riken, Hirosawa 2-1, Wako, Saitama, 351-0198, Japan is close to bouffée délirante (French traditional diagnosis), Degenerationspsychose (according to Kleist), or zykloide Psychosen (according to Leonhard). These categories are characterized by acute onset, phasic course, complete remission between psychotic episodes, and confusion, just like that observed in mild delirium. Needless to say, these characteristics resemble those of bipolar disorder. Although it is true that some patients having these features should be diagnosed as "psychotic disorder not otherwise specified" according to DSM-IV, many other patients having such symptoms can receive a DSM-IV diagnosis of bipolar disorder. However, in the Western part of Japan, patients having psychotic features, catatonic features, or confusion during manic episodes may receive a diagnosis of "atypical psychosis" and no specific DSM-IV diagnosis. When they are diagnosed according to the ICD-10 system, they tend to receive a diagnosis of acute and transient psychotic disorder. In some Japanese psychiatric wards for acute psychotic patients, no patients with bipolar disorder are admitted. On the contrary, many patients with "atypical psychosis" are admitted. This may lead to an under-diagnosis of bipolar disorder, especially the one with catatonic features, in Japan [3].

The concept of atypical psychosis led to important clinical achievements in Japan, such as prophylactic treatment with thyroid hormone, and prediction of good prognosis of acute psychotic episodes based on their symptomatology. However, the inter-rater reliability for this diagnosis was much lower than that for schizophrenia and bipolar disorder [4, 5]. If this diagnosis is overused, it can cause confusion in clinical practice.

However, it is also true that some patients have recurrent psychotic episodes that cannot be diagnosed as bipolar or as schizophreniform disorder, because they do not have any signs of mania or depression, or delusions and hallucinations. The diagnostic classification of these cases should be studied further.

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BiPolar Explained

BiPolar Explained

Bipolar is a condition that wreaks havoc on those that it affects. If you suffer from Bipolar, chances are that your family suffers right with you. No matter if you are that family member trying to learn to cope or you are the person that has been diagnosed, there is hope out there.

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