Tomifusa Kuboki

Effects of value and reward magnitude on feedback negativity and P300.

Feedback negativity is a negative component of the event-related brain potential observed 250–300 ms after feedback stimuli. The present study investigated the effects of value (correct or incorrect) and reward magnitude (no, small or large) on feedback negativity and P300. Feedback negativity was larger after incorrect feedback than after correct feedback, irrespective of reward magnitude. In contrast, P300 amplitude increased with reward magnitude, irrespective of value. The amplitude of feedback negativity was correlated with a trait score of negative affect and not positive affect, whereas P300 amplitude was correlated with positive affect and not negative affect. These results suggest that value and reward magnitude are processed separately in the brain.

Cerebral glucose metabolism associated with a fear network in panic disorder

The present study was performed to assess cerebral glucose metabolism in patients with panic disorder using positron emission tomography. 18F-fluorodeoxyglucose positron emission tomography with voxel-based analysis was used to compare regional brain glucose utilization in 12 nonmedicated panic disorder patients, without their experiencing panic attacks during positron emission tomography acquisition, with that in 22 healthy controls. Panic disorder patients showed appreciably high state anxiety before scanning, and exhibited significantly higher levels of glucose uptake in the bilateral amygdala, hippocampus, and thalamus, and in the midbrain, caudal pons, medulla, and cerebellum than controls. These results provided the first functional neuroimaging support in human patients for the neuroanatomical hypothesis of panic disorder focusing on the amygdala-based fear network.

Clinical and psychological aspects of restless legs syndrome in uremic patients on hemodialysis

BACKGROUND The pathogenesis of restless legs syndrome (RLS) is still unclear. The purpose of this study is to determine relationships of the presence of RLS in uremic patients regularly undergoing hemodialysis (HD) with demographic, clinical, and psychological factors. METHODS In 490 uremic patients on HD therapy in Japan, RLS was diagnosed based on diagnostic criteria established by the International Restless Legs Syndrome Study Group. Data were compared between patients with and without RLS. RESULTS There were univariately significant (P < 0.05) differences in serum phosphorus levels, anxiety levels determined using the Hospital Anxiety and Depression Scale, and degrees of emotion-oriented and avoidance-oriented coping determined using the Coping Inventory for Stressful Situations. In multivariate analyses, low hemoglobin levels, high serum phosphorus levels, high anxiety levels, and a great degree of emotion-oriented coping were independently related to the presence of RLS in uremic patients on HD therapy, with statistical significance (P < 0.05). CONCLUSION Hyperphosphatemia, anxiety, and a great degree of emotion-oriented coping with stress were independently related to the presence of RLS in uremic patients on HD therapy. The pathogenesis of RLS seems to involve more than one mechanism, which leads to restless legs as the final common pathway. These findings may provide new clues to the pathogenesis of RLS.

Error-related negativity reflects detection of negative reward prediction error.

Error-related negativity (ERN) is a negative deflection in the event-related potential elicited in error trials. To examine the function of ERN, we performed an experiment in which two within-participants factors were manipulated: outcome uncertainty and content of feedback. The ERN was largest when participants expected correct feedback but received error feedback. There were significant positive correlations between the ERN amplitude and the rate of response switching in the subsequent trial, and between the ERN amplitude and the trait version score on negative affect scale. These results suggest that ERN reflects detection of a negative reward prediction error and promotes subsequent response switching, and that individuals with high negative affect are hypersensitive to a negative reward prediction error.

Comorbidity of Irritable Bowel Syndrome, Panic Disorder, and Agoraphobia in a Japanese Representative Sample

OBJECTIVES:Irritable bowel syndrome (IBS) is considered to be a transcultural functional bowel disorder with high comorbidity and psychiatric disorders; but well-designed epidemiologic studies have never been performed in Japan. The purpose of this study was to establish the prevalence of IBS, together with the comorbidity rates of panic disorder (PD) and agoraphobia, employing a large-scale survey based on stratified random sampling.METHOD:A total of 4,000 subjects aged 20–69 years completed a questionnaire and the results were weighted to ensure representativeness of the Japanese general population. The questionnaire covered key symptoms of IBS, PD, and agoraphobia. The prevalence of IBS and its subtypes was calculated by gender. The comorbidity of PD and agoraphobia with IBS was compared with morbidity in non-IBS subjects; and comorbidity in IBS subjects who had consulted medical practitioners regarding their symptoms and in those who had not was also compared.RESULTS:The prevalence of IBS was 6.1% in total. It was significantly higher in females than in males. Diarrhea-predominant IBS was more prevalent in males and constipation-predominant IBS in females. The morbidity rates of PD and agoraphobia were significantly higher in IBS than in non-IBS subjects. Comorbidity did not differ between female and male IBS subjects, while morbidity was significantly higher in female than in male non-IBS subjects; and comorbidity did not differ between consulter and nonconsulter subjects.CONCLUSIONS:The prevalence of IBS and its comorbidity with PD and agoraphobia in Japan were demonstrated to be similar to those reported in Western industrialized countries.

Statistical Studies on Anorexia nervosa in Japan: Detailed Clinical Data on 1,011 Patients

Statistical studies on anorexia nervosa in Japan were carried out by our research group. Questionnaires were sent to physicians at 1,030 representative institutions throughout Japan and data were collected from 315 institutions. The total number of patients with anorexia nervosa in 1981 was 940 outpatients and 372 inpatients. The number of patients in 1981 was twice as high as in 1976. Detailed data on 1,011 patients were investigated. As most of the patients had certain endocrinological abnormalities which improved after weight gain, indications are that at least a part of the endocrinological abnormalities might be secondary changes due to weight loss.

Hikikomori, is it a culture-reactive or culture-bound syndrome? Nidotherapy and a clinical vignette from Oman.

Hikikomori, a form of acute social withdrawal, is becoming a silent epidemic in Japan. As it has not been reported from other parts of the world, hikikomori fulfills the criteria for “a culture-bound syndrome.” We report a case from Oman, in the southern part of Arabia, with all the essential features of hikikomori. We speculate that the social environment of Japanese and Omani society could reinforce behavior akin to hikikomori although this condition may also transcend geography and ethnicity.

Epidemiological data on anorexia nervosa in Japan

An epidemiological survey on anorexia nervosa was performed in Japanese hospitals in 1985 and 1992 using a questionnaire. The reported number of patients with anorexia nervosa was 2391 from 732 institutions. From these data, the total number of anorexia nervosa patients treated in 1985 in Japanese hospitals was estimated to be about 3500-4500. In 1992, the reported number of patients with AN was 2247. The total number of AN patients treated in 1992 was estimated to be about 4500-4600, which is a little higher than that in 1985 (3500-4500). The prevalence was 3.6-4.5 per 100000 among the general population, 6.3-9.7 per 10(5) among the female population, and 25.2-30.7 per 10(5) among the 13-29 year-old female population.

Reliability of recalled self‐report on headache intensity: investigation using ecological momentary assessment technique

Recalled evaluation of headache intensity is often affected by several factors. Recently, computerized ecological momentary assessment (EMA) has been developed to avoid such problems as recall bias. Here, we compared recalled headache intensity with momentary headache intensity using EMA in tension- type headache (TTH). Forty patients with TTH wore watch-type computers for 1 week to record momentary headache intensity and also rated their headache intensities by recall. We calculated intraclass correlation coefficients between recalled headache intensity and indices from EMA recordings in the whole study population and in two subgroups divided by variability of momentary headache intensity. The results showed that consistency and agreement of momentary and recalled headache intensity were low, and this was especially marked in the subjects whose headache varied widely. These observations suggested that variability of headache intensity may affect recall of headache intensity and this should be taken into consideration in both clinical and research settings.

Symptom profile of multiple chemical sensitivity in actual life.

Objective: This study was conducted to confirm the definition of multiple chemical sensitivity (MCS) in actual life: that multiple symptoms are provoked in multiple organs by exposure to, and ameliorated by avoidance of, multiple chemicals at low levels. We used the Ecological Momentary Assessment to monitor everyday symptoms and the active sampling and passive sampling methods to measure environmental chemical exposure. Methods: Eighteen patients with MCS, diagnosed according to the 1999 consensus criteria, and 12 healthy controls participated in this study. Fourteen patients and 12 controls underwent 1-week measurement of physical and psychologic symptoms and of the levels of exposure to various chemicals. Linear mixed models were used to test the hypotheses regarding the symptom profile of MCS patients. Results: Some causative chemicals were detected in 11 of 14 MCS patients. Two other patients did not report any hypersensitivity episodes, whereas passive sampling showed far less exposure to chemicals than control subjects. Another subject reported episodic symptoms but was excluded from the following analyses because no possible chemical was detected. Eleven of the 17 physical symptoms and all four mood subscales examined were significantly aggravated in the interview based on “patient-initiated symptom prompts.” On the other hand, there were no differences in physical symptoms or mood subscales between MCS patients and control subjects in the interview based on “random prompts.” Conclusions: MCS patients do not have either somatic or psychologic symptoms under chemical-free conditions, and symptoms may be provoked only when exposed to chemicals. AS = active sampling; AS–PS method = active sampling and passive sampling methods; CAS = the concentration of exposure estimated by the AS method; CFS = chronic fatigue syndrome; CPS = the concentration of exposure estimated by the PS method; CS = chemical sensitivity; DAMS = Depression and Anxiety Mood Scale; DNPH = 2,4-dinitrophenyl-hydrazine; ED = electronic diary; EESI = Environmental Exposure and Sensitivity Inventory; EMA = Ecological Momentary Assessment; FM = fibromyalgia; M.I.N.I. = Mini International Neuropsychiatric Interview; MCS = multiple chemical sensitivity; PS = passive sampling; RSD = relative standard deviation; RSDAS = RSD of repeatability test in the AS method; RSDPS = RSD of repeatability test in the PS method; VOCs = volatile organic compounds.