Atypical Psychosis

Among functional (endogenous) psychoses, the boundary between schizophrenia in the narrow sense and manic-depressive disorder is not necessarily clear clinically. Although it appears to be a mixture of the two, a group of psychoses that cannot be identified as either is collectively called atypical psychoses. It develops acutely or subacutely, with extreme emotional fluctuations and hallucinations and delusions, but improves relatively quickly and the prognosis is generally good. It is more common in women and has a strong tendency to recur. It can also develop spontaneously, but is often triggered by mental and physical stress. Some cases show reversible functional abnormalities in the limbic system as well as the diencephalon and pituitary system, and epileptic electroencephalographic abnormalities. In the standard diagnostic criteria DSM-IV and ICD-10, several diagnostic names correspond to this atypical psychosis.

It is a disease concept that developed primarily in Germany and Japan, and from a nosological perspective, the prevailing view is that it is an independent psychiatric area that touches or overlaps on the fringes of the three major typical mental disorders: schizophrenia, manic-depressive disorder, and epilepsy (all in the narrow sense), but there are also dissenting views.

[Tetsuo Fukuda]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

機能（内因）精神病のうち、狭義の統合失調症（精神分裂病）とそううつ病は臨床上かならずしもその境界が明確であるとはいえない。両者が混合しているようにみえるが、そのいずれとも特定できない一群の精神病を一括して非定型精神病とよぶ。急性ないし亜急性に発症し、感情の起伏が激しく、幻覚、妄想を伴うが、比較的短期間に軽快し、予後は概して良好である。女性に多く、再発の傾向が強い。自生的にも発症するが心身面でのストレスが契機になることが多い。辺縁系をはじめ間脳・下垂体系の可逆性の機能異常や、てんかん性の脳波異常を示すものもある。標準診断基準DSM‐ⅣやICD‐10では、いくつか複数の診断名がこの非定型精神病と符合している。

　もっぱらドイツと日本で発展した疾病概念であり、疾病学的には統合失調症、そううつ病、てんかん（いずれも狭義）の三大定型精神病の各辺縁部に接触ないし重畳している独立精神病圏とする見解が有力であるが、異論もある。

［福田哲雄］

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