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Articles by I. K Lyoo
Total Records ( 3 ) for I. K Lyoo
  I. K Lyoo , S. J Yoon , G Musen , D. C Simonson , K Weinger , N Bolo , C. M Ryan , J. E Kim , P. F Renshaw and A. M. Jacobson

Context  Neural substrates for low cognitive performance and depression, common long-term central nervous system–related changes in patients with type 1 diabetes mellitus, have not yet been studied.

Objective  To investigate whether prefrontal glutamate levels are higher in patients with type 1 diabetes and whether an elevation is related to lower cognitive performance and depression.

Design  Cross-sectional study.

Setting  General clinical research center.

Participants  One hundred twenty-three patients with adult type 1 diabetes with varying degrees of lifetime glycemic control and 38 healthy participants.

Main Outcome Measures  With the use of proton magnetic resonance spectroscopy, prefrontal glutamate–glutamine–-aminobutyric acid (Glx) levels were compared between patients and control subjects. Relationships between prefrontal Glx levels and cognitive function and between Glx levels and mild depressive symptoms were assessed in patients with type 1 diabetes.

Results  Prefrontal Glx concentrations were 9.0% (0.742 mmol/L; P = .005) higher in adult patients with type 1 diabetes than in healthy control subjects. There were positive linear trends for the effects of lifetime glycemic control on prefrontal Glx levels (P for trend = .002). Cognitive performances in memory, executive function, and psychomotor speed were lower in patients (P = .003, .01, and <.001, respectively) than in control subjects. Higher prefrontal Glx concentrations in patients were associated with lower performance in assessment of global cognitive function (0.11 change in z score per 1-mmol/L increase in Glx) as well as with mild depression.

Conclusions  The high prefrontal glutamate levels documented in this study may play an important role in the genesis of the low cognitive performance and mild depression frequently observed in patients with type 1 diabetes. Therapeutic options that alter glutamatergic neurotransmission may be of benefit in treating central nervous system–related changes in patients with adult type 1 diabetes.

  R. F Mollica , I. K Lyoo , M. C Chernoff , H. X Bui , J Lavelle , S. J Yoon , J. E Kim and P. F. Renshaw

Context  A pilot study of South Vietnamese ex–political detainees who had been incarcerated in Vietnamese reeducation camps and resettled in the United States disclosed significant mental health problems associated with torture and traumatic head injury (THI).

Objectives  To identify structural brain alterations associated with THI and to investigate whether these deficits are associated with posttraumatic stress disorder and depression.

Design  Cross-sectional neuroimaging study.

Setting  Massachusetts General Hospital and McLean Hospital.

Participants  A subsample of Vietnamese ex–political detainees (n = 42) and comparison subjects (n = 16) selected from a community study of 337 ex–political detainees and 82 comparison subjects.

Main Outcome Measures  Scores on the Vietnamese versions of the Hopkins Symptom Checklist–25 (HSCL) and Harvard Trauma Questionnaire for depression and posttraumatic stress disorder, respectively; cerebral regional cortical thickness; and manual volumetric morphometry of the amygdala, hippocampus, and thalamus.

Results  Ex–political detainees exposed to THI (n = 16) showed a higher rate of depression (odds ratio, 10.2; 95% confidence interval, 1.2-90.0) than those without THI exposure (n = 26). Ex–political detainees with THI had thinner prefrontotemporal cortices than those without THI exposure (P < .001 by the statistical difference brain map) in the left dorsolateral prefrontal and bilateral superior temporal cortices, controlling for age, handedness, and number of trauma/torture events (left superior frontal cortex [SFC], P = .006; left middle frontal cortex, P = .01; left superior temporal cortex [STC], P = .007; right STC, P = .01). Trauma/torture events were associated with bilateral amygdala volume loss (left, P = .045; right, P = .003). Cortical thinning associated with THI in the left SFC and bilateral STC was related to HSCL depression scores in THI-exposed (vs non–THI-exposed) ex–political detainees (left SFC, P for interaction = .007; left STC, P for interaction = .03; right STC, P for interaction = .02).

Conclusions  Structural deficits in prefrontotemporal brain regions are linked to THI exposures. These brain lesions are associated with the symptom severity of depression in Vietnamese ex–political detainees.

  J. E Kim , I. K Lyoo , A. M Estes , P. F Renshaw , D. W Shaw , S. D Friedman , D. J Kim , S. J Yoon , J Hwang and S. R. Dager

Context  There is substantial imaging evidence for volumetric abnormalities of the amygdala in younger children with autism spectrum disorder (ASD). The amygdala can be divided into functionally distinct laterobasal, superficial, and centromedial subregions. To date, we are not aware of any in vivo reports specifically assessing subregional amygdalar abnormalities in individuals with ASD.

Objectives  To evaluate alterations in subregional amygdalar morphology in children with ASD compared with typically developing (TD) children and to examine the relationships with ASD symptom severity.

Design  A cross-sectional study encompassing a narrow age range of children with ASD and age-matched TD children that evaluated magnetic resonance imaging–defined subregional morphology of the amygdala using a novel subregional analytic method.

Setting  Participants were recruited and clinically evaluated through the University of Washington Autism Center and imaged at the Diagnostic Imaging Sciences Center at the University of Washington. Imaging data were analyzed through the Brain Imaging Laboratory at the Seoul National University.

Participants  Fifty-one children 6 to 7 years of age (ASD, n = 31 and TD, n = 20) were assessed using magnetic resonance imaging and behavioral measures.

Main Outcome Measures  Volume and subregional measures of the amygdala and measures of social and communication functioning.

Results  The ASD group exhibited larger right and left amygdalae, by 12.7% and 11.0%, respectively, relative to the TD group. Subregional analysis revealed that the ASD group had enlarged laterobasal amygdalar subregions, relative to the TD group, after adjusting for age, sex, and hemispheric cerebral volume (P < .05, false discovery rate corrected and with clustered surface points >15). Exploratory analyses revealed that there were linear trends comparing a strictly defined subgroup of children with autistic disorder, who exhibited the greatest extent of laterobasal enlargement, followed by a subgroup of children with pervasive developmental disorder not otherwise specified and then the group of TD children (P for linear trend <.001). There were linear trends between enlargement of laterobasal subregions and lower levels of social and communication functioning (P < .001, P < .001, and P = .001 for 3 areas in the right laterobasal subregion; P < .001 for 1 area in the left laterobasal subregion).

Conclusion  The current study demonstrates bilateral enlargement of laterobasal subregions of the amygdala in 6- to 7-year-old children with ASD and that subregional alterations are associated with deficits in social and communicative behavior.

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