High-speed interband cascade infrared photodetectors: photo-response saturation by a femtosecond oscillator.

Interband cascade infrared photodetectors (ICIPs) combine interband optical transitions with fast intraband transport to achieve high-frequency and broad-wavelength operation at room temperature. Here we study the bias-dependent electronic impulse response of ICIPs with a mid-infrared synchronously pumped optical parametric oscillator (OPO). Since the OPO produces ultrashort 104-fs pulses, it is possible to probe the impulse response of the ICIP. From this impulse response, we identify two characteristic decay times, indicating the contribution of electron as well as hole carriers. A reverse bias voltage applied to the ICIP reduces both time scales and leads to an increased electrical cut-off frequency. The OPO emits up to 500 mW average power, of which up to 10 mW is directed to the ICIP in order to test its saturation characteristics under short-pulse illumination. The peak of the impulse response profile as well as the average photocurrent experience a gradual saturation behavior, and we determine the corresponding saturation powers by measuring the photo-response as a function of average power directed to the ICIP. We demonstrate that an increasing reverse bias increases the saturation power as well as the responsivity of the ICIP.

Rapid screening for major depression in post-myocardial infarction patients: an investigation using Beck Depression Inventory II items.

OBJECTIVE: To determine the ability of three questions from the Beck Depression Inventory II (BDI-II) to detect major depressive disorder (MDD) in a cohort of patients hospitalised for acute myocardial infarction (MI). DESIGN: Prospective observational study. SETTING: Coronary care unit and cardiac step-down unit of an urban academic medical centre. PATIENTS: 131 post-MI patients within 72 h of symptom onset. INTERVENTIONS: Patients were administered the BDI-II and participated in a structured diagnostic interview for MDD. Three individual BDI-II items (regarding sadness, loss of interest and loss of pleasure) were examined individually and in two-question combinations to determine their ability to screen for MDD. MAIN OUTCOME MEASURES: Sensitivity, specificity, negative and positive predictive values and proportion of patients with MDD correctly identified. RESULTS: The individual items and two-question combinations had good sensitivity (76-94%), specificity (70-88%) and negative predictive values (97-99%). Item 1 (sadness) performed the best of the individual items (48% with a positive response to the item had MDD; 3% with a negative response had MDD; over 80% of patients with MDD were correctly identified). A combination of questions about sadness and loss of interest performed best among the two-question combinations (37% with positive response had MDD v 1% with a negative response; 94% of patients with MDD were identified). CONCLUSIONS: One to two questions regarding sadness and loss of interest serve as simple and effective screening tools for post-MI depression.

Trauma, time and mental health: a study of temporal reintegration and Depressive Disorder among Southeast Asian refugees.

BACKGROUND: Prior research suggested that time splitting--suppressing the past and dissociating it from present and future--protected refugee mental health in the aftermath of catastrophe. The current study investigates temporal reintegration, defined as cognitive recapture of the past and reconnecting it with present and future, the mental health effects of temporal reintegration, and factors moderating the associated risk for Depressive Disorder. METHOD: A community sample of 608 Southeast Asian refugees, resettled in Vancouver British Columbia between 1979 and 1981, were interviewed on three separate occasions over a 10-year period. Participants performed a temporal orientation task and responded to questions about employment, social relations and mental health. Depressive Disorder, measured by a typology derived from Grade of Membership analysis of symptoms, constituted the dependent variable. Latent Growth Curve Analysis was used to examine both levels and rates of change in the probability of Depressive Disorder as predicted by changes in temporal reintegration, as well as the contribution of putative social and psychological moderators to explaining variations in growth parameters. RESULTS: Time relatedness increased over the duration of the study. Temporal reintegration jeopardized mental health. Employment and relational stability each moderated the mental health effects of temporal reintegration. CONCLUSIONS: Although time splitting may be effective in coping with adversity over the short-term, eventual temporal reintegration is probably ineluctable. Stability in love and work are protective factors, mitigating the mental health vicissitudes of temporal reintegration. Implications for optimal timing of clinical interventions are discussed.

Language acquisition, unemployment and depressive disorder among Southeast Asian refugees: a 10-year study.

The current study examines the risk-inducing effects of unemployment and the protective effects of language facility on the mental health of Southeast Asian refugees resettling in Canada. Rates of depression and of unemployment declined dramatically during the first decade after arrival. Although language fluency also improved during this period, approximately 8% of the sample spoke no English even after 10 years in the country. Initial depression was a strong predictor of subsequent depression. For males, job experience in Canada was the strongest predictor of subsequent employment whereas, for women, depression proved an important predictor of employability. For men in particular, unemployment was a potent risk factor for depression. During the initial period of resettlement, English-speaking ability had no effect on depression or on employment. However, by the end of the first decade in Canada. English language fluency was a significant predictor of depression and employment, particularly among refugee women and among people who did not become engaged in the labor market during the earliest years of resettlement. Study results demonstrate that the mental health salience of risk and protective factors changes according to the phase of resettlement.

Using biological indices to classify schizophrenia and other psychotic patients.

Although classification of mental disorders using more than clinical description would be desirable, there is scant evidence that available laboratory tests (i.e. biological indices) would provide more valid classifications than current diagnostic systems (e.g. DSM-IV). We used cluster analysis of four biological variables to classify 163 psychotic patients and 83 nonpsychiatric comparison subjects. Analyses revealed a three-cluster solution with the first cluster reflecting electrodermal deviance, the second cluster representing nondeviant biological function, and the third cluster reflecting increased nailfold plexus visibility and ocular motor dysfunction. To assess the construct validity of proband clusters we examined ocular motor performance in 156 first-degree relatives as a function of proband cluster membership. First-degree relatives of third cluster probands exhibited worse ocular motor performance than relatives of other cluster probands. Additionally, better classification sensitivity and specificity were obtained for the relatives when they were grouped by proband cluster than by proband DSM-IV diagnosis. When a single proband characteristic (i.e. eyetracking performance) was used to group relatives, classification sensitivity and specificity failed to significantly increase over grouping by proband DSM-IV diagnosis. Multivariate biologically defined clusters may offer an advantage over DSM-IV classification when examining nosology and etiology of psychotic disorders.

The structure of attention-deficit and hyperactivity symptoms among native and non-native elementary school children.

This study evaluated the psychometric properties of a measure of Attention-Deficit/Hyperactivity Disorder (ADHD) with Native and non-Native children. Two models, corresponding to DSM-III-R and DSM-IV symptom categorizations of ADHD, were assessed by (a) determining which DSM schema of ADHD best fit the data within each culture group and (b) testing the cross-cultural equivalence of the best-fitting model. Data were taken from the Flower of Two Soils and School Options for Native Children studies, examinations of emotional health and academic achievement among Native and non-Native children. The studies included teacher, parent, and self-report ratings of symptoms among 1555 Native and 489 non-Native children in grades 2 and 4 at four different locations across North America. For the data derived from teacher and parent ratings, a 2-factor solution corresponding to the DSM-IV conceptualization of two subtypes provided the best fit. For student self-ratings, the 2-factor solution showed no improvement over a 1-factor model. The respective factor solutions were culturally invariant. Acceptable internal consistency was observed across raters and within culture groups.

Clinical and biological concomitants of resting state EEG power abnormalities in schizophrenia.

BACKGROUND: This study investigated the clinical and biological concomitants of electroencephalogram power abnormalities in schizophrenia. METHODS: We examined the power characteristics of resting electroencephalograms in 112 schizophrenic patients. Also collected were measures of psychotic symptomatology, brain morphology, ocular motor functioning, electrodermal activity, and nailfold plexus visibility. Seventy-eight nonschizophrenic psychosis patients (e.g., mood disorder patients with psychosis) and 107 nonpsychiatric control subjects were included for comparison. RESULTS: Schizophrenic patients whose electroencephalograms were characterized by augmented low-frequency power and diminished alpha-band power had more negative symptoms, larger third ventricles, larger frontal horns of the lateral ventricles, increased cortical sulci widths, and greater ocular motor dysfunction compared with schizophrenic patients without these electroencephalogram characteristics. In nonschizophrenic psychosis patients, augmented low-frequency and diminished alpha-band powers failed to be associated with any clinical or biological indices. CONCLUSIONS: Results suggest that clinical and biological concomitants of low-frequency and alpha-band power abnormalities in schizophrenia are unique, perhaps indicating the presence of thalamic and frontal lobe dysfunction.

Perceived racial discrimination, depression, and coping: a study of Southeast Asian refugees in Canada.

Using data obtained from personal interviews with 647 Southeast Asian refugees in Canada, this study tests hypotheses regarding both the association between perceived racial discrimination and depression, and the roles of coping and ethnic identity in conditioning the nature of the discrimination-depression relation. Refugees who reported that they had experienced racial discrimination had higher depression levels than their counterparts who reported no such experiences. Responding to discrimination through confrontation was not significantly associated with depression. Study findings support the effectiveness of forbearance in diminishing the strength of the association between discrimination and depression. The moderating effect of forbearance was conditioned by the level of ethnic identity: The beneficial effect of forbearance was significantly greater among those holding stronger ethnic identification. Cultural and situational interpretations of the findings are presented.

Relationship between nailfold plexus visibility and clinical, neuropsychological, and brain structural measures in schizophrenia.

BACKGROUND: Although all published studies investigating the association between nailfold plexus visibility and schizophrenia have found the subpapillary plexus (the vascular network into which capillaries drain) to be unusually visible in many schizophrenia patients, little else is known about this putative marker for schizophrenia liability. METHODS: Plexus visibility was rated in 63 chronic schizophrenia, 67 first-episode schizophrenia, 9 schizophreniform, and 66 unipolar and bipolar depressed patients, all with psychosis, and 119 nonpsychiatric controls. Smooth-pursuit eye tracking, clinical features, neuropsychological performance, and lateral ventricle size were assessed. RESULTS: Approximately 21% of chronic schizophrenia, 22% of first-episode schizophrenia, and 22% of schizophreniform patients had highly visible plexus compared to only 8% of unipolar, bipolar, and nonpsychiatric controls. Schizophrenia patients with visible plexus had worse oculomotor performance. Additionally, chronic schizophrenia patients with visible plexus had more negative symptoms, worse course, more severe illness, worse occupational functioning, and worse neuropsychological performance on tasks thought to be sensitive to frontal dysfunction. An inverse relationship between plexus visibility and lateral ventricle size was found. CONCLUSIONS: This study provides evidence that schizophrenia patients with plexus visibility are characterized by oculomotor dysfunction, negative symptoms, severe symptomatology, chronic course, neuropsychological dysfunction, and an absence of enlarged ventricles.

Optimal haloperidol dosage in first-episode psychosis.

OBJECTIVE: To determine optimal doses of haloperidol for the treatment of a first episode of psychosis. METHOD: A 4-week prospective controlled clinical trial with "optimal dose" defined as the dose at which either of the following occurs: 1) significant improvement, defined as a 15% or greater decrease in scores on the Positive And Negative Syndrome Scale (PANSS), or 2) the onset of extrapyramidal symptoms. Beginning with 2 mg daily, haloperidol was increased weekly to 5 mg, 10 mg, and finally 20 mg daily until either 1) or 2) occurred. RESULTS: Optimal doses for the 36 subjects were 2 mg daily for 15 subjects, 5 mg daily for 11, 10 mg daily for 7, and 20 mg daily for 3. On average, subjects whose optimal dose was 2 mg daily showed the greatest improvement. Among the 27 subjects evidencing clinical response to treatment, 20 had plasma haloperidol levels below 5 ng/ml. CONCLUSION: Many people suffering a first psychotic episode respond to haloperidol doses well below levels in common use.

Electrodermal activation in first-episode psychotic patients and their first-degree relatives.

We hypothesized that electrodermal deviations evident in patients with schizophrenia would also be present in their biological relatives and examined the specificity of abnormal EDA to schizophrenia patients and their families. One hundred and thirty-five first-episode psychotic patients with either schizophrenia or other psychotic disorders; 104 non-psychiatric comparison subjects; 178 relatives of these subjects; and a comparison group of 61 patients with chronic schizophrenia had their EDA monitored while they listened to auditory stimuli. Electrodermal non-responding, regardless of the nature of the stimulus, was common to all patient groups and tended to run in families. However, non-responding did not differentiate the relatives of the psychotic patients from those of non-psychiatric subjects. Responders in both the chronic and first-episode schizophrenia patients showed an excessively high rate of non-specific fluctuations (NSFs), as did the first-degree relatives of the first-episode patients. Patients with major depression had more NSFs than normal, but significantly so only during one of the tone series. Their relatives, however, had a high NSF rate in both tone series. The results indicate that a high NSF rate may represent a psychophysiological marker of risk for schizophrenia and psychotic depression. Electrodermal non-responding is not specific to schizophrenia and is not likely to be useful as an indicator of genetic risk.

Social support predicts 5-year outcome in first-episode schizophrenia.

Investigations of social support in schizophrenia have been relatively sparse. In this research, patients with 1st-episode schizophrenia or affective psychosis were asked to describe supportive social relationships immediately prior to their 1st lifetime treatment contact and were interviewed 18 months and 5 years later for assessment of their social and occupational functioning. The results indicated that 18-month adaptive functioning was lower than in the year prior to 1st treatment contact but at 5 years rose above that seen both at baseline and 18 months. Moreover, social support from nonfamily members of the social network predicted 5-year adaptive functioning in the schizophrenia (n = 54) group but not in the affective psychosis (n = 55) group. Support from family did not predict 5-year outcome in either group. Together, these findings replicate and extend earlier findings that social support predicts outcome in 1st-episode schizophrenia.

Mental health and the academic performance of first nations and majority-culture children.

Prior classroom achievement and verbal IQ are identified as predictors of school performance for both Native and non-Native youngsters. Children's assessments of their competence, which appear to be, in part, a product of interactions with teachers, were found to be independent predictors of classroom performance. Results suggest that verbal IQ and compromised self-assessments contribute to the difficulties many Native children experience in majority-culture schools.

MRI correlates of treatment response in first episode psychosis.

It is not known whether the magnitude of the structural brain abnormalities that underlie schizophrenia is a determinant of the extent to which patients respond to antipsychotic medication. This study was undertaken in order to explore this relationship. Twenty-six patients receiving treatment for a first episode of psychosis were involved in both a study measuring treatment response and a magnetic resonance imaging (MRI) study. In the treatment study, haloperidol dose was increased weekly beginning at 2 mg/day until patients showed evidence of a response or extrapyramidal symptoms. MRI scans were analyzed using a computerized volumetric approach to yield estimates of cerebrospinal fluid (CSF), gray-matter and white-matter volumes. Improvement in positive and negative symptoms after 1 week of treatment was significantly correlated with cortical gray-matter volumes. Those patients who were maintained on 2 mg/day of haloperidol had greater cortical gray-matter volume than those who were treated with higher doses. The severity of structural brain abnormalities at the onset of psychosis may contribute to individual variation in response to antipsychotic medication. It remains to be determined whether the degree to which particular domains of symptomatology can improve is related to the severity of structural brain pathology in specific brain regions.

Depression and conduct disorder in native and non-native children.

OBJECTIVE: To compare depression and conduct disorder symptoms between North American Native and non-Native children as rated by teacher, parent, and self-reports. METHOD: The sample included 1,251 Native children in grades 2 and 4 in four different settings across North America and comparison samples of 457 non-Native children. Parents, teachers, and children rated children's mental health using culturally sensitive measures of depression and conduct disorder symptoms. RESULTS: According to parent ratings and child self-reports, there were no Native/non-Native differences in levels of conduct disorder symptoms. However, non-Native teachers rated higher levels of conduct disorder symptoms among Native children compared with non-Native students. Children reported higher levels of depression than the adults rating them. CONCLUSIONS: Results challenge assertions about high levels of psychopathology among Native youngsters. Cultural distance may introduce a negative bias in teacher evaluations of Native children's mental health.

An investigation of ethnic and gender differences in the pharmacodynamics of haloperidol.

The objective of this study was to examine neuroleptic effectiveness among Asians and Caucasians, and to investigate inter-ethnic pharmacodynamic differences. Asians and Caucasians suffering a first episode of psychosis were maintained on low oral doses of haloperidol (2 mg/day) for the first week of treatment. Doses were increased weekly until the optimal therapeutic dosage was achieved. This was defined as the point at which subjects: (a) experienced significant clinical improvement; or (b) developed extrapyramidal side effects. Plasma haloperidol and prolactin were measured at intake, at the end of first week of the treatment on haloperidol 2 mg/day, and at optimal therapeutic dosage. The average optimal dosage for Asians and Caucasians was equal. However, at the end of the first week of haloperidol at a fixed dose of 2 mg, Caucasian males had significantly lower plasma haloperidol levels than Asian males while no ethnic differences in haloperidol levels were found among females. There were no ethnicity or gender effects on plasma prolactin response after 1 week of treatment. Ethnicity and gender may affect haloperidol metabolism.

Refugees' time perspective and mental health.

OBJECTIVE: The authors' goal was to investigate factors protective of the mental health of refugees, with a particular focus on time splitting and suppression of the past. METHOD: Structured interviews covering premigration and postmigration stresses, personal and social resources, and mental health were given to 1,348 Southeast Asian refugees resettled in Vancouver, British Columbia, and to a comparison sample of 319 residents of Vancouver. Both groups of subjects also performed a task designed to measure orientation toward past, present, and future. RESULTS: Compared with resident Canadians, refugees were more likely to exhibit an atomistic time perspective in which past, present, and future are split. Temporal atomism and avoidance of nostalgia were associated with a lower risk of depression than were other time perspectives. CONCLUSIONS: Under conditions of extreme adversity, time splitting and suppression of the past may be adaptive strategies, mitigating the risk of depression.

Cross-cultural measurements of psychological well-being: the psychometric equivalence of Cantonese, Vietnamese, and Laotian translations of the Affect Balance Scale.

OBJECTIVES: This paper evaluates the cultural equivalence of Cantonese, Vietnamese, and Laotian translations of the Affect Balance Scale. METHODS: The scale was completed by 399 Vietnamese, 193 Laotian, 756 Cantonese, and 319 English speakers who were participants in the Clarke Institute-University of Toronto Refugee Resettlement Project (n = 1667). RESULTS: Confirmatory factor analyses indicated a good fit between the hypothesized two-factor model (separate factors for positive and negative affect) across the original English-language version and each of the Asian-language translations. Factorial invariance (numbers and patterns of factor loadings) was evident across all versions of the scale. No evidence of item bias was detected by mixed Language x Item analyses of variance. Acceptable reliability was observed; coefficient alphas ranged from .62 to .72 for positive affect and from .62 to .70 for negative affect items. CONCLUSIONS: These findings substantiate the cultural equivalence of the three translations of the scale for population health research. Important future research directions made possible by the availability of culturally equivalent instruments are discussed.

Season of birth and electroencephalogram power abnormalities in schizophrenia.

To determine the association between season of birth and electroencephalogram (EEG) power abnormalities in schizophrenia, this study examined the resting EEGs of 28 winter-born and 81 nonwinter-born schizophrenia patients. Eighteen winter-born and 58 nonwinter-born nonschizophrenic psychosis patients (e.g., bipolar disorder patients with psychotic features), and 97 normal subjects were also studied. Compared to normal subjects, nonwinter-born schizophrenia patients had augmented low-frequency power and diminished alpha band power, but winter-born schizophrenia patients failed to have any EEG power abnormalities. Nonwinter-born nonschizophrenic psychosis patients had the same low-frequency and alpha band power abnormalities as nonwinter-born schizophrenia patients. The winter-born non-schizophrenic psychosis group failed to show any EEG power abnormalities. The results of this study indicate that in psychosis the functional characteristics of the brain vary depending on the season in which a person is born. Low-frequency and alpha band EEG power abnormalities may help distinguish psychosis stemming from a seasonally varying pathogen from psychosis of other etiologies.

Negative labelling of individuals with first episode schizophrenia: the effect of premorbid functioning.

This study examines the hypothesis that negative labelling of individuals with a first episode of schizophrenia is related to the length and intensity of behavioural disturbance prior to first hospitalization. Forty-five individuals with first episode schizophrenia were assessed at admission to hospital for the presence and severity of symptoms, duration of untreated illness and premorbid social and occupational functioning. Negative labelling was assessed from ratings obtained from individuals designated as a significant other by the individuals with schizophrenia. Identical measures of labelling were obtained from individuals designated as a significant other by a comparison group (n = 70) who had no history of psychiatric disorder. The results indicated that the individuals with schizophrenia received more negative labels than the asymptomatic individuals. The negative attributions were associated with older age at onset of psychosis, a long period of deterioration before the onset of psychosis, and poor occupational functioning in the 9 months prior to hospitalization. These findings are consistent with results from studies that have examined expressed emotion (EE) in first episode schizophrenia and suggest that the reported association of high EE with relapse in first episode schizophrenia may be confounded with premorbid functioning that is typically associated with poor outcome.