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Biomedical subjects

Maria A Ron

Publications and source records attributed to Maria A Ron.

9 recordsLinked to original sources
PubMed2006

Bipolar I and bipolar II disorder: cognition and emotion processing.

BACKGROUND: Cognitive impairment may be part of the endophenotype of bipolar disorder (BP), but little is known about patterns and severity of impairment in BP subgroups and their relation to depression. The same applies to deficits in emotion processing known to be present in BP. METHOD: To explore the relationship between depression and impairment in cognition and emotion processing and the differences between BP subgroups, we assessed 36 (25 BP I and 11 BP II) patients using a cognitive battery and a facial emotion recognition task. RESULTS: BP patients were impaired compared to published norms on memory, naming and executive measures (Binomial Single Proportion tests, p<0.05). Cognitive performance was largely unrelated to depression ratings. Surprise recognition was the only emotion processing impairment in BP patients compared to controls (patients' recognition score 75% v. controls' 89%, p=0.024). Patients with higher depression ratings were more impaired in recognizing expressions of anger (t23=2.21, p=0.037). BP II patients were more impaired than BP I patients in IQ, memory and executive measures (Mann-Whitney tests, p<0.05). Depression severity or exposure to medication or electroconvulsive therapy (ECT) did not explain these differences. CONCLUSIONS: We confirm cognitive impairment and an isolated facial emotion processing deficit in BP patients and suggest that these deficits are largely unrelated to depressive symptoms. Our study also provides evidence that cognitive deficits are more severe and pervasive in BP II patients, suggesting that recurrent depressive episodes, rather than mania, may have a more detrimental and lasting effect on cognition.

Adult↗
PubMed2006

A volumetric MRI and magnetization transfer imaging follow-up study of patients with first-episode schizophrenia.

Conventional MRI studies have not provided definitive evidence of progressive loss of brain volume in the early stages of schizophrenia, although more subtle changes may have gone undetected. We have looked for such subtle changes using volumetric MRI and magnetization transfer imaging (MTI), an advanced MRI technique sensitive to subtle neuropathological abnormalities. Magnetization transfer images and high-resolution volumetric T1-weighted images were acquired from 16 patients with first-episode schizophrenia at the start of the study and 3.7 years later. A group of 12 healthy controls were also scanned on two occasions. Images were processed using a voxel-based approach that allows whole-brain analysis. There was a group difference with a significant volume loss in the patients' white matter adjacent to the lateral ventricles in the right and left temporal lobes, in medial temporal gyrus, and in the white matter in and around the right middle frontal gyrus. No cortical differences were detected between the groups using MTI or volumetric MRI. The absence of any time-by-group interaction suggests that these abnormalities do not progress in the early stages of the disease. The results of the study need to be interpreted in the light of the small sample size and of the limitations of current image analysis methods.

Adolescent↗
PubMed2004

Structural neural networks subserving oculomotor function in first-episode schizophrenia.

BACKGROUND: Smooth pursuit and antisaccade abnormalities are well documented in schizophrenia, but their neuropathological correlates remain unclear. METHODS: In this study, we used statistical parametric mapping to investigate the relationship between oculomotor abnormalities and brain structure in a sample of first-episode schizophrenia patients (n = 27). In addition to conventional volumetric magnetic resonance imaging, we also used magnetization transfer ratio, a technique that allows more precise tissue characterization. RESULTS: We found that smooth pursuit abnormalities were associated with reduced magnetization transfer ratio in several regions, predominantly in the right prefrontal cortex. Antisaccade errors correlated with gray matter volume in the right medial superior frontal cortex as measured by conventional magnetic resonance imaging but not with magnetization transfer ratio. CONCLUSIONS: These preliminary results demonstrate that specific structural abnormalities are associated with abnormal eye movements in schizophrenia.

Adolescent↗
PubMed2004

Cognitive abnormalities in schizophrenia and schizophrenia-like psychosis of epilepsy.

Twenty-six patients with schizophrenia and 12 patients with schizophrenia-like psychosis of epilepsy (SLPE) were compared to 38 healthy volunteers and 12 nonpsychotic patients with epilepsy to determine the contribution of psychosis to the pattern of cognition. Tests of memory and executive function were used. The schizophrenic group was more cognitively impaired than the SLPE and comparison groups. The profile of neuropsychological impairment in SLPE resembled that of schizophrenia and is unlikely to be explained solely by temporal lobe dysfunction. These results do not support the concept of SLPE as an independent nosological entity.

Adult↗
PubMed2003

Frontal lobe N-acetylaspartate correlates with psychopathology in schizophrenia: a proton magnetic resonance spectroscopy study.

INTRODUCTION: Clinical, neuropsychological and functional neuroimaging studies in schizophrenia suggest impaired frontal lobe function, especially of the dorsolateral prefrontal region (DLPFR). This dysfunction has in particular been associated with negative or "deficit" symptoms. Despite these findings, morphological studies have failed to show consistent structural abnormalities in the frontal lobe. This may be because existing techniques are not sensitive enough to detect structural abnormalities or that dysfunction in the frontal lobe is caused by lesions elsewhere. We used volume-localised proton magnetic resonance spectroscopy (1H-MRS) to measure N-acetylaspartate (NAA), a neuronal marker, to evaluate the neuronal integrity of the dorsolateral prefrontal region in schizophrenic patients with persistent negative symptoms and in healthy comparison subjects. METHOD: Twenty-five patients who fulfilled DSM-IV criteria for schizophrenia and met the criteria for the Deficit syndrome were compared to 26 healthy controls matched for age and gender. Bilateral proton MR spectra were collected from a 2-cm(3) volume in the dorsolateral prefrontal region and the absolute concentrations of N-acetylaspartate, choline (Cho) and creatine+phosphocreatine (Cr+PCr) were measured. RESULTS: There was a significant negative correlation between severity of symptoms and NAA concentration in the schizophrenic patients. This was more marked for positive symptoms and for general psychopathology than for negative symptoms. There was also a significant correlation between NAA concentration and social functioning within the schizophrenic group. There were no significant differences between the two groups for the three metabolites. CONCLUSIONS: The negative association between severity of symptoms and NAA in schizophrenic patients and an association of NAA with social functioning suggest that NAA may be an indicator of disease severity. The lack of significant mean difference in NAA between the two groups suggests that there is no marked neuronal loss in the dorsolateral prefrontal region in schizophrenia.

Adult↗
PubMed2003

Gray and white matter brain abnormalities in first-episode schizophrenia inferred from magnetization transfer imaging.

BACKGROUND: Neuroimaging studies suggest that schizophrenia is associated with gray and possibly white matter changes. It is unclear whether these changes are present at illness onset or which brain structures are selectively affected. New imaging methods such as magnetization transfer imaging may be more sensitive than conventional volumetric imaging to the subtle structural brain changes in schizophrenia. METHODS: High-resolution volumetric T1-weighted images and magnetization transfer images were acquired from 30 patients (29 with first-episode schizophrenia and 1 with schizophreniform psychoses) and 30 control subjects. Images were processed using voxel-based morphometry, which allows whole-brain analysis. RESULTS: Compared with controls, the magnetization transfer ratio (an index of signal loss derived from magnetization transfer imaging) was reduced bilaterally in the medial prefrontal cortex (right greater than left), insula (left greater than right), and white matter incorporating the fasciculus uncinatus (left greater than right) in the patient group. Analysis of the T1-weighted images did not reveal significant volumetric differences between patients and controls. CONCLUSIONS: Gray and white matter abnormalities are present in schizophrenia at illness onset. The magnetization transfer ratio is sensitive to these abnormalities, which cannot be explained by detectable atrophy in our patient group.

Adolescent↗
PubMed2002

A magnetization transfer analysis of the thalamus in schizophrenia.

The authors investigated the thalamus in schizophrenia by using magnetization transfer ratio (MTR), a novel structural magnetic resonance technique sensitive to subtle neuropathological abnormalities. The dorsomedial nucleus (DMN) and pulvinar were selected because of their connections to limbic, prefrontal, and temporal regions, putatively relevant in schizophrenia. Volume (intracranial; thalamic) and MTR (whole thalamus; DMN; pulvinar) were determined in 25 patients with chronic schizophrenia by DSM-IV criteria and 25 control subjects. There were no significant differences between patients and control subjects in thalamic volume (corrected for intracranial volume) or MTR in whole thalamus, DMN, or pulvinar. No volumetric or MTR abnormalities could be detected in the thalamus of patients with schizophrenia. The findings suggest that abnormalities, if present, are very subtle and beyond the power of resolution of these techniques.

Adult↗