インターフェロンによる精神症状—Wieckの通過症候群による考察

Psychiatric Symptoms Induced by Interferon Treatment: discussion concerning the transient syndrome of Wieck

　【抄録】C型慢性肝炎におけるインターフェロン療法によって種々の精神症状（抑うつ，不安焦燥，軽躁，健忘症状，傾眠）を呈した5例に対して，脳波，高次脳機能検査を継続的に行った。脳波では3例に徐波化，3例に低振幅とα波の出現率の低さを認めた。高次脳機能検査では4例に図形認知障害，4例にWAIS-Rでの動作性IQの低得点を認めた。また「緩慢な思考」と「（自ら訂正可能な程度の）不注意な間違え」が特徴的に観察された。臨床症状，脳波，高次脳機能検査の結果から，全例に軽度から重度の意識混濁が存在すると考えられた。各症例の病像の変化はWieck，Hの通過症候群を中心とした機能性精神病の概念によく合致する。

　It is well known that various psychiatric manifestations are frequently associated with Interferon (IFN) therapy in patients with chronic type-C hepatitis. Although depression has been reported to occur without obvious disturbance of consciousness, mild clouding of consciousness in the strict sence of the term was not excluded in these cases. In this paper we examined five cases with various psychiatric symptoms (depression, anxiety, agitation, manic state, amnestic state, and lethargy) using repeated observations of electroencephalography (EEG) and neuropsychological tests, and discussed whether or not there was clouding of consciousness in IFN-induced psychotic states.

　All EEGs observed when above symptoms were present showed abnormal findings. There was slowing of background activity in three patients and low voltage activities and poor appearance of alpha rhythm in three patients. Neuropsychological tests were performed in all patients.Four patients had visuoconstructional dysfunction. Four patients showed low scores of performance IQ. Slowness of thinking and carelessness corrected by the patient himself, and which was reversible in nature, were observed as characteristic signs. All these EEGs, neuropsychological tests and clinical symptoms offer evidence suggesting that there existed clouding of consciousness in varying degree in all patients.

　Depression, affective disorder, amnestic state and clouding of consciousness in our cases fit Durchgangs-Syndrome (Transient syndrome) and clouding of consciousness in Funktionspsychosen proposed by Wieck H. Psychiatric symptoms induced by IFN share Transient syndrome in many respects. The concept of Functionspsychosen including Transient syndrome is thought to be very useful for understanding psychiatric symptoms induced by IFN.