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Dive into the research topics where Chika Obara is active.

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Featured researches published by Chika Obara.


Schizophrenia Research | 2014

A naturalistic longitudinal study of at-risk mental state with a 2.4 year follow-up at a specialized clinic setting in Japan

Masahiro Katsura; Noriyuki Ohmuro; Chika Obara; Tatsuo Kikuchi; Fumiaki Ito; Tetsuo Miyakoshi; Hiroo Matsuoka; Kazunori Matsumoto

OBJECTIVE The notion of at-risk mental state (ARMS) is valuable for identifying individuals in a putative prodromal state of psychosis and for reducing conversion risk by pharmacological and psychological interventions. However, further systematic study is required because 1) diagnostic reliability in various clinical settings is not yet established; 2) predictive ability is insufficient; 3) optimal interventions in diversified populations are elusive; and 4) little evidence from non-Western regions exists. METHODS A naturalistic longitudinal study was conducted at a specialized clinic for early psychosis at a university hospital in Sendai, Japan. Individuals with ARMS (n=106) were recruited and followed up with case-by-case treatment. RESULTS Two-thirds of the participants were psychiatrist referrals, and 83 were followed up for at-least 1 year (mean follow-up=2.4 years). Fourteen developed psychosis and the estimated (by Kaplan-Meier) cumulative transition rate was 11.1% at 12, 15.4% at 24, and 17.5% at 30 months. At the end-point, about 30% of the 83 followed-up participants including 11 converters received antipsychotic medication. Compared to non-converters, converters showed more severe attenuated psychotic symptoms, including ego-boundary disturbance, formal thought disorder, and emotional disturbance. CONCLUSIONS The present study replicated previous major Western longitudinal studies, in terms of clinical characteristics, psychosis transition rate, and antipsychotic prescription rate. Our results emphasize the importance of phenomenological assessment of ARMS and intensive care in a clinical setting.


Schizophrenia Research | 2015

The association between cognitive deficits and depressive symptoms in at-risk mental state: A comparison with first-episode psychosis

Noriyuki Ohmuro; Kazunori Matsumoto; Masahiro Katsura; Chika Obara; Tatsuo Kikuchi; Yumiko Hamaie; Atsushi Sakuma; Kunio Iizuka; Fumiaki Ito; Hiroo Matsuoka

Cognitive deficits and a high prevalence of depressive symptoms have been reported in at-risk mental state (ARMS) for psychosis, but the relationships between these variables remain unclear. The Brief Assessment of Cognition in Schizophrenia (BACS) was administered to 50 individuals with ARMS, 50 with first-episode psychosis (FEP), and 30 healthy controls (HC). Clinical symptoms were assessed by the Positive and Negative Syndrome Scale (PANSS) and the Beck Depression Inventory-2nd edition (BDI-II). Composite z-scores in BACS were compared between the three groups. Pearson correlations between composite z-scores on the BACS and indices of clinical symptoms were compared in the ARMS and FEP groups. The mean composite z-scores on the BACS for the ARMS (-2.82) and FEP (-2.85) groups were significantly lower than the HC group (P<0.001); no differences between the ARMS and FEP groups emerged (P=0.995). Cognitive deficits and depressive symptoms were significantly correlated in the ARMS group (PANSS depression: r=-0.36, P=0.010; BDI-II: r=-0.34, P=0.02), while the correlation between cognitive deficits and negative symptoms was significant in the FEP group (r=-0.46, P=0.001) and approached significance in the ARMS group (r=-0.25, P=0.08). The correlation between cognitive deficits and depressive symptoms significantly differed between the ARMS and FEP groups (PANSS depression: Z=2.50, P=0.012; BDI-II: Z=1.96, P=0.0499). Thus, a relationship between cognitive deficits and depression appears to be specific to ARMS compared to FEP.


Schizophrenia Bulletin | 2017

Reduced Thickness of the Anterior Cingulate Cortex in Individuals With an At-Risk Mental State Who Later Develop Psychosis

Yoichiro Takayanagi; Sue Kulason; Daiki Sasabayashi; Tsutomu Takahashi; Naoyuki Katagiri; Atsushi Sakuma; Chika Obara; Mihoko Nakamura; Mikio Kido; Atsushi Furuichi; Yumiko Nishikawa; Kyo Noguchi; Kazunori Matsumoto; Masafumi Mizuno; J. Tilak Ratnanather; Michio Suzuki

BACKGROUND Despite the fact that only a part of the individuals with at-risk mental state (ARMS) for psychosis do develop psychosis, biological markers of future transition to psychosis have not been well documented. Structural abnormality of the anterior cingulate gyrus (ACG), which probably exists prior to the onset of psychosis, could be such a risk marker. METHODS We conducted a multicenter magnetic resonance imaging (MRI) study of 3 scanning sites in Japan. 1.5-T 3D MRI scans were obtained from 73 ARMS subjects and 74 age- and gender-matched healthy controls. We measured thickness, volume, and surface area of the ACG using labeled cortical distance mapping and compared these measures among healthy controls, ARMS subjects who later converted to overt psychosis (ARMS-C), and those who did not (ARMS-NC). RESULTS Seventeen of 73 (23%) ARMS subjects developed overt psychosis within the follow-up period. The thickness of the left ACG was significantly reduced in ARMS-C relative to healthy subjects (P = .026) while both ARMS-C (P = .001) and ARMS-NC (P = .01) had larger surface areas of the left ACG compared with healthy controls. CONCLUSION Further studies will be needed to identify potential markers of future transition to psychosis though cortical thinning of the ACG might be one of the candidates.


Psychiatry Research-neuroimaging | 2016

Deficits of cognitive theory of mind and its relationship with functioning in individuals with an at-risk mental state and first-episode psychosis

Noriyuki Ohmuro; Masahiro Katsura; Chika Obara; Tatsuo Kikuchi; Atsushi Sakuma; Kunio Iizuka; Yumiko Hamaie; Fumiaki Ito; Hiroo Matsuoka; Kazunori Matsumoto

Disturbance of theory of mind (ToM) and its relationship with functioning in schizophrenia is well documented; however, this is unclear in spectrum disorders like at-risk mental state (ARMS) and first-episode psychosis (FEP). To assess mental state reasoning ability, the total score of the Theory of Mind Picture Stories Task questionnaire was compared among 36 Japanese individuals with ARMS, 40 with FEP, and 25 healthy controls (HC). Pearsons correlations between ToM performance and global and social functioning indices were examined. ToM performance for FEP and ARMS subjects was significantly lower than that for HC, though the significance of the difference between the ARMS and HC disappeared when controlling for premorbid IQ. ToM deficits in ARMS subjects were confirmed only in the comprehension of higher-order false belief. Only among FEP subjects were ToM performance and global functioning significantly correlated, though the significance disappeared when controlling for neurocognitive performance or dose of antipsychotics. No significant correlation between ToM performance and social functioning was observed in the FEP and ARMS groups. The current findings suggest that ToM deficits emerge in ARMS subjects confined within a higher-order domain, and that the relationship between ToM impairment and functional deterioration might be established after psychosis onset.


European Archives of Psychiatry and Clinical Neuroscience | 2018

Surface morphology of the orbitofrontal cortex in individuals at risk of psychosis: a multicenter study

Mihoko Nakamura; Tsutomu Takahashi; Yoichiro Takayanagi; Daiki Sasabayashi; Naoyuki Katagiri; Atsushi Sakuma; Chika Obara; Shinsuke Koike; Hidenori Yamasue; Atsushi Furuichi; Mikio Kido; Yumiko Nishikawa; Kyo Noguchi; Kazunori Matsumoto; Masafumi Mizuno; Kiyoto Kasai; Michio Suzuki

Changes in the surface morphology of the orbitofrontal cortex (OFC), such as a fewer orbital sulci and altered sulcogyral pattern of the ‘H-shaped’ orbital sulcus, have been reported in schizophrenia, possibly reflecting abnormal neurodevelopment during gestation. However, whether high-risk subjects for developing psychosis also exhibit these gross morphologic anomalies is not well documented. This multicenter MRI study from four scanning sites in Japan investigated the distribution of the number of intermediate and posterior orbital sulci, as well as the OFC sulcogyral pattern, in 125 individuals with an at-risk mental state (ARMS) [of whom 22 later developed psychosis (ARMS-P) and 89 did not (ARMS-NP)] and 110 healthy controls. The ARMS group as a whole had a significantly lower number of intermediate and posterior orbital sulci compared with the controls, which was associated with prodromal symptomatology. However, there was no group difference in OFC pattern distribution. The ARMS-P and -NP groups did not differ in OFC surface morphology. These results suggest that gross morphology of the OFC in high-risk subjects may at least partly reflect neurodevelopmental pathology related to vulnerability to psychosis.


Schizophrenia Research | 2017

The relationship between cognitive insight and cognitive performance among individuals with at-risk mental state for developing psychosis

Noriyuki Ohmuro; Masahiro Katsura; Chika Obara; Tatsuo Kikuchi; Yumiko Hamaie; Atsushi Sakuma; Kunio Iizuka; Fumiaki Ito; Hiroo Matsuoka; Kazunori Matsumoto

Impairments in cognitive insight-the capacity to appraise and modify ones own distorted beliefs-are believed to be associated with the formation of psychosis. Nevertheless, the association between cognitive insight and cognitive function among people with at-risk mental state (ARMS) for developing psychotic illness has not been made clear. In this study, we used the Beck Cognitive Insight Scale (BCIS) to assess cognitive insight and the Brief Assessment of Cognition in Schizophrenia (BACS) and the Wisconsin Card Sorting Test (WCST) to assess cognitive functions. Fifty subjects with ARMS and 29 healthy volunteers were recruited as participants. The scores for the two groups on the BCIS, BACS, and WCST were compared and Spearmans rank correlations between the domains of the BCIS and cognitive performance were examined in each group. No significant differences were found in BCIS scores between these groups, whereas all of the cognitive function scores were poorer in the participants with ARMS. In the ARMS group, higher self-certainty on the BCIS was significantly correlated with lower performance in the mean number of categories achieved (ρ=-0.31, P=0.03) and perseverative errors of the Nelson type (ρ=0.29, P=0.04) on the WCST. This indicates that excessively high self-certainty might be linked with weaknesses in cognitive flexibility or set-shifting ability in people with ARMS.


Psychiatry Research-neuroimaging | 2017

The associations between quality of life and clinical symptoms in individuals with an at-risk mental state and first-episode psychosis

Noriyuki Ohmuro; Kazunori Matsumoto; Yu Ishii; Masahiro Katsura; Chika Obara; Tatsuo Kikuchi; Yumiko Hamaie; Fumiaki Ito; Hiroo Matsuoka

Quality of life (QOL) is strongly associated with severity of clinical symptoms and is often compromised in patients with chronic or first-episode psychosis (FEP). However, it remains unclear whether baseline QOL in individuals with an at-risk mental state (ARMS) for psychosis is higher or lower than that in patients with FEP, or what specific clinical symptoms relate to a decreased QOL in individuals with ARMS and FEP. The World Health Organizations WHOQOL-BREF, an instrument assessing QOL, was administered to 104 individuals with ARMS and 53 with FEP. Clinical symptoms were assessed by the Positive and Negative Syndrome Scale and the Beck Depression Inventory-II. We compared the four domain scores of the WHOQOL-BREF between the two groups, and calculated Pearson correlations between each WHOQOL-BREF domain score and the clinical symptoms and compared these correlations between the groups. We observed significant correlations between poor QOL and severity of depressive symptoms in both the FEP and ARMS group. No between-group differences were found in any correlation coefficients between WHOQOL-BREF domains and clinical symptoms. Thus, depressive symptoms should be investigated as a key factor relating to poor QOL in both individuals with ARMS and those with FEP.


Asian Journal of Psychiatry | 2018

No regional gray matter volume reduction observed in young Japanese people at ultra-high risk for psychosis: A voxel-based morphometry study

Atsushi Sakuma; Chika Obara; Masahiro Katsura; Fumiaki Ito; Noriyuki Ohmuro; Kunio Iizuka; Tatsuo Kikuchi; Tetsuo Miyakoshi; Hiroo Matsuoka; Kazunori Matsumoto

OBJECTIVES Structural brain magnetic resonance imaging studies of individuals at ultra-high risk (UHR) for psychosis have shown subtle but widespread reductions in baseline gray matter volume (GMV) in the frontal, temporal, and limbic regions compared with healthy controls (HC). These regions coincide with regions of reduced GMV in patients with established psychosis and have led to the consideration of structural changes in UHR as a potential biomarker for future transition to psychosis. However, most studies have been from Europe, North America, and Australia, with few reports from other regions, and two recent studies from Asian countries have failed to detect regional GMV reduction in UHR, suggesting the need for further analysis of an Asian sample. In this study, we investigated GMV reduction in Japanese UHR subjects. RESULTS The study used voxel-based morphometry to compare magnetic resonance imaging brain scans between 45 UHR individuals recruited by a specialist and 33 HCs. This showed no significant GMV reduction in the UHR group compared with the healthy control group. This negative result may be attributable to characteristics of Asian samples, such as a low prevalence of illicit drug use, or to the heterogeneous nature of UHR subjects.


Biological Psychiatry | 2017

Increased Occipital Gyrification and Development of Psychotic Disorders in Individuals With an At-Risk Mental State: A Multicenter Study

Daiki Sasabayashi; Yoichiro Takayanagi; Tsutomu Takahashi; Shinsuke Koike; Hidenori Yamasue; Naoyuki Katagiri; Atsushi Sakuma; Chika Obara; Mihoko Nakamura; Atsushi Furuichi; Mikio Kido; Yumiko Nishikawa; Kyo Noguchi; Kazunori Matsumoto; Masafumi Mizuno; Kiyoto Kasai; Michio Suzuki


Schizophrenia Research | 2014

Poster #S153 CLINICAL AND FUNCTIONAL COURSE OF YOUTHS AT ULTRA-HIGH RISK FOR PSYCHOSIS: OUTCOMES OF NON-CONVERTERS IN JAPAN

Masahiro Katsura; Noriyuki Ohmuro; Chika Obara; Tatsuo Kikuchi; Yumiko Hamaie; Emi Sunakawa; Fumiaki Ito; Tetsuo Miyakoshi; Atsushi Sakuma; Hiroo Matsuoka; Kazunori Matsumoto

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