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Peg Nopoulos

Publications and source records attributed to Peg Nopoulos.

16 recordsLinked to original sources
PubMed2006

Evaluation of the GTRACT diffusion tensor tractography algorithm: a validation and reliability study.

Fiber tracking, based on diffusion tensor imaging (DTI), is the only approach available to non-invasively study the three-dimensional structure of white matter tracts. Two major obstacles to this technique are partial volume artifacts and tracking errors caused by image noise. In this paper, a novel fiber tracking algorithm called Guided Tensor Restore Anatomical Connectivity Tractography (GTRACT) is presented. This algorithm utilizes a multi-pass approach to fiber tracking. In the first pass, a 3D graph search algorithm is utilized. The second pass incorporates anatomical connectivity information generated in the first pass to guide the tracking in this stage. This approach improves the ability to reconstruct complex fiber paths as well as the tracking accuracy. Validation and reliability studies using this algorithm were performed on both synthetic phantom data and clinical human brain data. A method is also proposed for the evaluating reliability of fiber tract generation based both on the position of the fiber tracts, as well the anisotropy values along the path. The results demonstrate that the GTRACT algorithm is less sensitive to image noise and more capable of handling areas of complex fiber crossing, compared to conventional streamline methods.

Algorithms↗
PubMed2006

Functional abnormalities in the neural circuitry of reading in men with nonsyndromic clefts of the lip or palate.

OBJECTIVE: The current study was designed to evaluate the neurobiology of reading in a group of men with nonsyndromic clefts of the lip or palate (NSCLP) compared with healthy controls by positron emission tomography. DESIGN: SUBJECTS included eight men with NSCLP compared with six healthy control men. By using radioactively labeled water (O(15)), regional brain blood flow was obtained during the performance of three simple reading tasks: reading unrelated words, reading unrelated sentences, and reading a story. RESULTS: During each of the reading conditions, NSCLP subjects compared with healthy controls showed increased blood flow in areas previously reported to be involved in language processing and reading (inferior frontal lobe, cerebellum, and occipital lobe). The increased blood flow suggests a possible neural inefficiency. In contrast, when analyzing the brain regions involved in more complex language functioning (reading stories compared with reading only words), control subjects showed an increase in blood flow in a distributed neural circuit, whereas the NSCLP subjects showed a decrease in flow in these regions. Additionally, the NSCLP subjects had activation of several regions not activated in the healthy controls, suggesting a compensatory circuit used for this more complex reading task. CONCLUSIONS: These results indicate that subjects with NSCLP show abnormalities in the function of the distributed neural circuitry used for oral reading.

Adult↗
PubMed2005

Effects of atypical and typical neuroleptics on anterior cingulate volume in schizophrenia.

We have previously found typical neuroleptic exposure to be correlated with an increase in anterior cingulate volume over time in patients with schizophrenia. However, the effect of atypical neuroleptics on anterior cingulate volume and the clinical significance of these changes are not known. To determine if atypicals differ from typicals in their effect on anterior cingulate volume change over time and to assess the clinical significance of such changes, subjects with schizophrenia were compared to normal controls over time. Anterior cingulate volume was delineated with manual traces on magnetic resonance images of the brain in 31 neuroleptic-naïve subjects and 18 normal controls at admission and 2-3 years later. Neuroleptic exposure for each subject was calculated using a dose-year formula. Increased typical neuroleptics exposure over time was correlated to increased anterior cingulate volume over time (r = 0.92, p < 0.001), while increased atypical neuroleptics exposure was correlated to decreased anterior cingulate volume (r = -0.57, p < 0.006). Increased anterior cingulate volume was correlated to greater psychotic symptom improvement (r = 0.78, p < 0.010). Anterior cingulate volume changes over time are correlated differently with atypical versus typical neuroleptic exposure over time. The increase in anterior cingulate volume with typicals is correlated to improved psychotic symptoms over time.

Adult↗
PubMed2005

Globus pallidus volume is related to symptom severity in neuroleptic naive patients with schizophrenia.

This study compares globus pallidus (GP) volume between neuroleptic naive patients with schizophrenia and healthy controls using structural MRI. The volume of the external segment of the GP (GPe) was positively correlated with the severity of global symptoms, as measured by the Scale for the Assessment of Negative Symptoms and Scale for the Assessment of Positive Symptoms (SANS/SAPS, Andreasen and Olsen, 1982). The volume for the GP, GPe, and internal segment (GPi) did not differ between groups.

Adult↗
PubMed2005

Insular cortex abnormalities in schizophrenia: Relationship to symptoms and typical neuroleptic exposure.

BACKGROUND: The insular cortex is a limbic integration region engaged in emotional and cognitive functions. Previously, we found that neuroleptic-naive subjects had abnormally small insular volumes compared with control subjects, with volume directly related to severity of psychotic symptoms. METHODS: To further investigate insular cortex abnormalities and their functional correlates, we measured insular gray matter volume and cortical surface size, using magnetic resonance images among 30 patients with schizophrenia and a matched control group. The sample was designed to represent a variety of phenomenologic profiles to provide sufficient variance in multiple measures, including severity of illness and exposure to neuroleptics (typical only). RESULTS: There were no significant differences in morphology between patients and control subjects; however, among patients, psychotic symptoms were inversely correlated with insular volume, replicating our previous finding in neuroleptic-naive subjects. Neuroleptic exposure had a specific effect on insular morphology: increasing drug exposure (measured in dose-years) correlated with larger insular volume. CONCLUSIONS: This effect of neuroleptic exposure might account for the lack of difference in structural measures in this more chronic sample, whereas the initial study on neuroleptic-naive subjects showed group differences. Further research is needed to investigate the potential relationship between changes in insula volume from neuroleptic exposure and clinical outcome.

Adult↗
PubMed2005

Morphology of the anterior cingulate gyrus in patients with schizophrenia: relationship to typical neuroleptic exposure.

OBJECTIVE: The anterior cingulate gyrus is a pivotal component of brain networks directing affective and cognitive functions, and abnormalities of the anterior cingulate gyrus may be involved in the pathophysiology of schizophrenia. However, magnetic resonance imaging studies of the morphology of this region have been few and the results inconsistent. Many of the studies have not accounted for confounding factors such as gender, handedness, or clinical variables such as neuroleptic exposure. METHOD: The morphology and clinical correlates of the anterior cingulate gyrus were evaluated in a group of 30 right-handed male subjects with schizophrenia and a comparison group matched for age, sex, and handedness. The patient group was specifically designed to provide measures of multiple phenomenological differences such as severity of illness, duration of illness, and exposure to typical neuroleptics. RESULTS: The patient group had a significantly larger left anterior cingulate gyrus volume relative to comparison subjects, whereas right anterior cingulate gyrus volume did not differ between groups. Depth of the left anterior cingulate gyrus was significantly correlated with neuroleptic exposure, indicating that greater exposure to neuroleptics was associated with greater cortical depth of this region. There was no significant relationship between anterior cingulate gyrus morphology and duration of illness or severity of symptoms. CONCLUSIONS: Anterior cingulate gyrus depth in subjects with schizophrenia is directly related to typical medication exposure (the greater the exposure, the thicker the anterior cingulate gyrus) but not to other clinical variables such as length of illness or symptom severity. Future research is needed to determine the functional consequences of these changes and relationship to atypical neuroleptic use.

Adult↗
PubMed2005

Subgenual prefrontal cortex volumes in major depressive disorder and schizophrenia: diagnostic specificity and prognostic implications.

OBJECTIVE: A variety of findings have implicated the portion of the anterior cingulate cortex ventral to the corpus callosum in the pathophysiology of familial depressive disorder. There are, as yet, few data to address the specificity of these abnormalities to depressive disorders or to characterize their stability over time. METHOD: The authors studied 10 subjects who were judged to have had major depressive disorder with psychotic features, who underwent magnetic resonance imaging (MRI) protocols, and who participated in a longitudinal study of recent-onset psychosis. These were group-matched to 10 subjects with schizophrenia and to 10 well comparison subjects. Volumetric measures were made of the posterior and anterior portions of the subgenual prefrontal cortex for these 30 subjects. Follow-up scans done an average of 4 years after intake were available for seven subjects with major depressive disorder, nine subjects with schizophrenia, and five well comparison subjects. RESULTS: Volumes of the left side of the posterior subgenual prefrontal cortex differed significantly by group and were smallest for the group with psychotic major depressive disorder. Volumes of the anterior subgenual prefrontal cortex did not differ significantly by group. Patients with major depressive disorder were more likely to show increases in posterior subgenual prefrontal cortex volume on follow-up than were comparison subjects or patients with schizophrenia. CONCLUSIONS: These findings add to the evidence that abnormalities in the subgenual region of the anterior cingulate play a role in at least some types of mood disorder.

Adult↗
PubMed2005

Ventral frontal cortex morphology in adult males with isolated orofacial clefts: relationship to abnormalities in social function.

OBJECTIVE: In a previous magnetic resonance imaging (MRI) study, men with nonsyndromic clefts of the lip and/or palate (NSCLP) were found to have abnormalities in the structure of the frontal lobe of the brain. Moreover, many subjects with nonsyndromic clefts of the lip and/or palate have been described as being socially inhibited. A subregion of the frontal lobe, the ventral frontal cortex (VFC), has been shown to be related to social function. This study was designed to evaluate the morphology of the ventral frontal cortex in men with nonsyndromic clefts of the lip and/or palate, and the morphology's relationship to social function. METHODS: Subjects were 46 men with nonsyndromic clefts of the lip and/or palate and 46 sex matched controls. Social function was assessed using a standardized scale. The morphology of the ventral frontal cortex (composed of the orbitofrontal cortex [OFC] and the straight gyrus [SG]) was obtained from magnetic resonance imaging scans using the software BRAINS. RESULTS: After controlling for frontal lobe gray matter, the patient group had significant reductions in orbitofrontal cortex volume and area. The straight gyrus was not morphologically abnormal. Measures of orbitofrontal cortex morphology were significantly correlated to measures of social function--the greater the structural abnormality, the greater the social dysfunction. CONCLUSION: Compared with healthy controls, subjects with nonsyndromic clefts of the lip and/or palate showed morphologic abnormalities in the cortical surface anatomy of a brain region known to govern social function, the orbitofrontal cortex. Moreover, the structural abnormality in this brain region was directly correlated with social function.

Adult↗
PubMed2004

Morphometry of the superior temporal plane in schizophrenia: relationship to clinical correlates.

A magnetic-resonance-imaging-based method of cortical parcellation was used to evaluate the morphology of the superior temporal plane and its subregions (Heschl's gyrus [HG], planum temporale [PT], and planum polare [PP]) in a group of 30 patients with schizophrenia versus a matched group of healthy subjects. Right HG volume was significantly reduced in patients compared with control subjects. Each subregion showed a unique set of structure/function relationships: reduced volumes of the HG were associated with greater duration of illness; reduced volumes of the PT were associated with positive symptoms; and in most contrast, elevated volumes of the PP were associated with cumulative neuroleptic exposure.

Adult↗
PubMed2003

Morphology of the lateral superior temporal gyrus in neuroleptic nai;ve patients with schizophrenia: relationship to symptoms.

OBJECTIVE: The superior temporal gyrus (STG) is a large structure in the temporal lobe with multiple sub-regions that are structurally and functionally distinct. This study evaluates the structural morphology of a specific sub-region of the STG, the anterior and posterior portions of the lateral aspect of the STG. Furthermore, relationships between the morphology of these regions and symptoms of the illness were explored. METHOD: Regions of cortex were consecutively traced on a set of serial coronal slices in 25 male neuroleptic nai;ve patients with first episode schizophrenia and 25 age-matched healthy volunteers. Regional gray matter volumes were calculated and compared, and their correlations with three symptom dimensions were explored. RESULTS: The left anterior STG had a significant inverse correlation with psychotic symptoms, whereas the right posterior STG had a significant positive correlation with negative symptoms. These findings were confirmed by a follow-up analysis using extreme groups. There was no significant correlation between any region and disorganized symptoms. CONCLUSIONS: These findings suggest that abnormalities in the lateral side of the STG may be associated with both psychotic and negative symptoms through different pathophysiological mechanisms.

Adult↗
PubMed2003

Progressive structural brain abnormalities and their relationship to clinical outcome: a longitudinal magnetic resonance imaging study early in schizophrenia.

BACKGROUND: Many studies have shown that structural brain abnormalities in schizophrenia are already present by the time of index evaluation of first-episode patients. However, whether these abnormalities progressively worsen during the subsequent course of the disorder remains unresolved. METHODS: To study the longitudinal progression of structural brain abnormalities, high-resolution multispectral magnetic resonance images obtained on 73 recent-onset schizophrenic patients and 23 controls were analyzed using state-of-the-art, well-validated, and highly reliable neuroimaging tools. The mean duration between initial and follow-up MRIs was 3 years. Repeated-measures analysis of covariance was carried out to determine (1) whether brain volume changes differed between patients and controls and (2) the significance of regional brain changes on functional outcome in schizophrenia. RESULTS: We found accelerated enlargement in cortical sulcal cerebrospinal fluid spaces early in the course of schizophrenia. Instead of the usual trajectory of volume enlargement, patients showed progressive reduction in frontal lobe white matter volume. A reciprocal increase in frontal lobe cerebrospinal fluid volume also occurred at a more rapid rate in patients than in controls. In keeping with most of our a priori hypotheses, patients with poor outcome had greater lateral ventricular enlargement over time than patients with good outcome. Progressive decrement in frontal lobe white matter volume and enlargement in frontal lobe cerebrospinal fluid volume were associated with greater negative symptom severity. Reductions in frontal lobe gray and white matter volumes correlated with poorer executive functioning. CONCLUSIONS: There are ongoing changes in the brains of schizophrenic patients during the initial years after diagnosis despite ongoing antipsychotic drug treatment. These progressive changes seem to be most evident in the frontal lobes and to correlate with functional impairment. Disruptions in neurodevelopment or neural plasticity may act alone or in combination to bring about these progressive brain deficits in schizophrenia.

Adult↗
PubMed2002

Cognitive dysfunction in adult males with non-syndromic clefts of the lip and/or palate.

Cognitive deficits have been well-documented in children with non-syndromic clefts of the lip and/or palate. However, no study to date has formally assessed cognition in adults with oral clefts. This study was designed to evaluate neuropsychological functioning in adult males with non-syndromic clefts of the lip and/or palate (n=50) compared to age and sex-matched controls. Subjects with oral clefts were found to have significantly lower full scale IQ, performance IQ and verbal IQ scores compared to their matched controls. After controlling for IQ, patients showed specific deficits in verbal fluency. Adult males with oral clefts manifest a specific pattern of cognitive deficits. As the development of the face is highly interdependent with the development of the brain, it is theorized that the etiology of these cognitive deficits is a primary problem with abnormal brain development.

Cleft Lip↗
PubMed2002

Longitudinal assessment of premorbid cognitive functioning in patients with schizophrenia through examination of standardized scholastic test performance.

OBJECTIVE: Studies suggest the presence of premorbid cognitive impairment in patients with schizophrenia, yet the onset and course of these deficits remain unclear. The purpose of this study was to investigate the longitudinal course of premorbid cognitive functioning in individuals with schizophrenia by using prospective data obtained from scholastic test results. METHOD: Scores from grades 4, 8, and 11 on the Iowa Tests of Basic Skills and the Iowa Tests of Educational Development were obtained for 70 subjects who later developed schizophrenia. The mean percentile rank of the subjects' scores in the areas of vocabulary, reading comprehension, language, mathematics, sources of information, and an overall composite category were compared with state norms. RESULTS: The subjects scored below the 50th percentile for each category in all three grades, but only language, reading, sources of information, and composite scores from grade 11 were significantly below state norms. With regard to longitudinal course, there was a significant linear decrease in language scores over time. Scores from grade 11 were positively correlated with WAIS-R IQ, verbal fluency, and Rey Auditory Verbal Learning scores at first illness episode. Scores from grade 11 were not significantly correlated with age at illness onset or ratings of disorganized, psychotic, or negative symptoms. CONCLUSIONS: Scholastic test scores at grades 4 and 8 were nonsignificantly below average in this group of children who later developed schizophrenia. However, test scores dropped significantly between grades 8 and 11. This corresponds to ages 13-16 years, or the onset of puberty. Poor or declining scholastic performance may be a precursor to the cognitive impairment seen during the first episode of illness.

Adolescent↗
PubMedDate not supplied

Secondary prevention of schizophrenia: utility of standardized scholastic tests in early identification.

BACKGROUND: Given the enormous societal burden of schizophrenia, there has been a growing interest in its prevention during the past decade. Early detection and prompt treatment may improve outcome in schizophrenia. In this study, we examine the value of using pre-morbid cognitive impairment in early detection. METHODS: Standardized achievement tests Iowa Test of Basic Skills (ITBS) and Iowa Tests of Educational Development (ITED) at Grades 4, 8 and 11 were examined in 70 patients with schizophrenia and 147 comparison subjects without schizophrenia. The majority of comparison subjects later developed another major mental illness such as substance abuse or mood disorder. Receiver operating characteristic curves were used to test the efficiency and accuracy of pre-morbid cognitive tests for differentiating adolescents who will later develop schizophrenia from those who remain well or develop another mental illness. RESULTS: Although schizophrenia patients had lower mean percentile ranks than comparison subjects in every ITBS/ITED sub-test, these differences were only associated with small increases in risk for schizophrenia. Standardized scholastic tests achieved moderate sensitivity and specificity, and enhanced the detection of schizophrenia by three to five fold. However, positive predictive values were low. ITBS/ITED scores alone cannot be used in screening the general population, given the low positive predictive values. CONCLUSION: Combining ITBS/ITED scores with other risk factors, such as family history, may lead to more efficient early detection. Our findings illustrate the challenges facing the secondary prevention of schizophrenia. Priority should be given to developing efficient and accurate methods of early detection in order to reduce the dangers of making erroneous false positive diagnoses, and to decrease exposure to unnecessary treatment during the testing of early interventions.

Achievement↗
PubMedDate not supplied

Structural brain abnormalities in adult males with clefts of the lip and/or palate.

PURPOSE: To evaluate brain morphology of adult males with nonsyndromic clefts of the lip and/or palate (NSCLP) in comparison to a matched healthy control group. METHODS: Brain structure was measured using quantitative analysis of magnetic resonance images. RESULTS: Subjects with NSCLP had significant abnormalities in brain morphology consisting of abnormally enlarged anterior regions of the cerebrum, and decreased volumes of the posterior cerebrum and cerebellum. Overall, the most severely affected region was the left temporal lobe. Furthermore, these structural abnormalities were directly related to cognitive dysfunction. CONCLUSIONS: These findings highlight the important relationship and interplay between face and brain development.

Abnormalities, Multiple↗