[Dispatch of Psychiatrists to Okinawa and their Activities].

As a part of the medical assistance project for Okinawa, where the land and their people were devastated by the Pacific War, the Japanese Government launched a program to dispatch medical doctors. The dispatch of psychiatrists started in 1964, and lasted for 13 years. During this period, a total of 83 doctors joined this project. Their term was 3-6 months. To promote the smooth implementation of this program, the Japanese Society of Psychia- try and Neurology (JSPN) established the Committee of Mental Health Care for Okinawa (CMHCO) and supported their activities. This support included : 1) supporting medical care in hospitals/counseling in public health centers, 2) activities for promoting mental health/com- munity-based psychiatric treatment, 3) guidance and advice for local medical workers, and 4) sharing opinions with Ryukyu and Japanese governments. The CMCHO's activities contributed to improve the mental health care condition in Oki- nawa. Now, the qualities of facilities and human resources are above the national average. Rates of the isolation and restraint of inpatients, which indicate the quality of care, are low. The CMCHO's activities have written a significant page in the history of JSPN as well as Oki- nawa's mental health care.

Increased rate of P300 latency prolongation with age in drug-naive and first episode schizophrenia.

OBJECTIVE: Previous studies have found an increased rate of P300 latency prolongation with age in medicated chronic patients with schizophrenia, suggesting a pathological neurodegenerative process. In this study, we investigated whether this abnormality was identified in drug-naive and first episode patients with schizophrenia. METHODS: P300 from auditory stimuli was recorded from 20 drug naive and first episode male patients with schizophrenia and compared with 23 age and handedness matched healthy male controls. The relationship of P300 latency and P300 amplitude to age in each group was evaluated using polynomial regression analyses. RESULTS: Reduction of P300 amplitude was significant in drug-naive and first episode schizophrenia patients. P300 amplitude negatively correlated with age in schizophrenia patients but not in controls. Although the prolongation of P300 latency with age was observed in both groups, the regression slope for P300 latency with age was significantly steeper in patients with schizophrenia than in normal controls. Significant overall curvilinear correlations with age were also found for P300 latency and amplitude in patients with schizophrenia, and for P300 latency in normal controls. CONCLUSIONS: The greater increase in P300 latency and reduction in P300 amplitude with age may be a primary neuropathological effect of schizophrenia. SIGNIFICANCE: This study suggests that neurodegenerative processes are involved in the etiology of schizophrenia.

The N200 abnormalities of auditory event-related potentials in patients with panic disorder.

Cognitive impairment in patients with panic disorder (PD) has been studied using event-related potentials (ERPs). However, previous studies obtained ERP data only at a few scalp sites, and seldom investigated N200 measurements from the difference waveforms. In the present study, auditory ERPs were recorded at 16 scalp sites during an active discrimination task of oddball paradigm. Fourteen PD patients (8 with agoraphobia; 6 without agoraphobia) were compared with 14 sex- and age-matched control subjects. For the nontarget waveforms, P2 amplitude was reduced in PD patients. For the target waveforms, a topographical difference between female PD patients and female controls was found for N200 amplitude, which attenuated in female PD patients over the parietal area. Two subcomponents of N200, N2a and N2b, were measured from the difference waveforms. A significant group difference was found for N2b amplitude, which reduced in PD patients compared with unaffected control subjects. It is suggested that N2b reduction reflects an abnormally controlled processing of stimulus information in PD.

N400 abnormalities in unmedicated patients with schizophrenia during a lexical decision task.

A lexical decision task was used to investigate semantic processing in schizophrenia. Eighteen unmedicated schizophrenics and 18 gender/age-matched controls were tested. Subjects were visually presented with pairs of words. The target word (S2) was either a non-word, semantically related, or unrelated to preceding word (S1). Subjects decided whether the S2 was a word or non-word. Event related potentials (ERPs) elicited by the S2, including N350, and the late positive component (LPC) were measured. The latency of the N350 was prolonged in schizophrenia. The N400 effect, measured by the mean amplitude (300-500 ms) from difference waves (unrelated word-related word, non-word-related word), was smaller in patients. Peak amplitude of the LPC was reduced and latency of the LPC was delayed in the schizophrenics. Behaviorally, control subjects responded much faster to related words compared to unrelated or non-words, while patients showed little difference in processing speed between word categories. A reduced N400 effect suggested inefficient utilization of the context, while prolonged latency of the ERP components suggested a general delay of semantic information processing in schizophrenia.

Abnormalities of auditory P300 cortical current density in patients with schizophrenia using high density recording.

While P300 current density analysis has been performed in schizophrenic patients, the event-related potential data have never been obtained using a high density recording, nor have their cortical images been well demonstrated. In this study, the auditory P300 elicited by an oddball paradigm was recorded using a high density recording system of 128 channels. Thirteen male patients who met DSM-IV criteria for schizophrenia were compared with 20 healthy male controls. The cortical current density analysis of low resolution electromagnetic tomography (LORETA) was applied to the P300 component, and this resulted in the values of 6222 current density points over the surface of a cortex model. The inter-group difference of P300 current density was assessed using a point-by-point comparison by t-test. While the normal controls demonstrated the cortical activation of bilateral frontal, temporal and parietal cortex during the oddball paradigm, visual inspection suggested that in the schizophrenic patients these areas were less activated. The inter-group significance of P300 current density was dominant over the left hemisphere, and particularly over the left prefrontal area. It is concluded that the LORETA current density analysis localizes the neural activity from the cortical fronto-temporo-parietal network as the neural substrates of the scalp recorded P300. The dysfunction of such a network, especially over the left hemisphere, possibly subserves the scalp recorded P300 abnormality in schizophrenia.