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Biomedical subjects

M S Keshavan

Publications and source records attributed to M S Keshavan.

At least 73 records · Page 4Linked to original sources
PubMed1997

Eye-tracking dysfunction in offspring from the New York High-Risk Project: diagnostic specificity and the role of attention.

Eye tracking abnormalities were studied in the offspring of schizophrenic, unipolar depressed and bipolar probands from the New York High-Risk Project to examine their familial specificity. Offspring of schizophrenic and depressed probands both had significant global performance deficits based on spectral purity measurements, but only the offspring of schizophrenic probands had an increased rate of intrusive anticipatory saccades. The greater specificity of high anticipatory saccade rate than global performance impairment suggests that this eye movement abnormality may provide a more specific biological marker of risk for schizophrenia than the global measure of eye tracking performance used in this study. Attention facilitation effectively normalized all performance deficits in the offspring of schizophrenic patients, suggesting that a problem sustaining focused visual attention may contribute to eye tracking deficits observed in the relatives of schizophrenic probands.

Adolescent↗
PubMed1997

Frontostriatal measurement in treatment-naive children with obsessive-compulsive disorder.

BACKGROUND: Abnormalities in frontostriatal circuits have been implicated in obsessive-compulsive disorder (OCD). Although OCD commonly emerges during childhood or adolescence, few studies have examined frontostriatal anatomy in psychotropic-naive children with OCD near the onset of illness to determine the possible role of atypical developmental processes in this disorder. METHODS: Magnetic resonance imaging scans from 19 children with OCD who had not been exposed to psychotropic drugs, aged 7 to 18 years, and 19 case-matched healthy control subjects were analyzed to determine the volumes of the following structures: prefrontal cortex, striatum (caudate and putamen), lateral and third ventricles, and intracranial volume. RESULTS: Patients with OCD had significantly smaller striatal volumes and significantly larger third ventricle volumes than controls, but did not differ in prefrontal cortical, lateral ventricular, or intracranial volumes. Striatal volumes were inversely correlated with OCD symptom severity but not illness duration. CONCLUSIONS: Our findings provide new evidence of abnormalities of the striatum in pediatric OCD. These results are preliminary, given the small sample size.

Adolescent↗
PubMed1997

Hypofrontality in schizophrenia: influence of normalization methods.

1. Studies with Single Photon Emission Computed Tomography (SPECT) in schizophrenia research have utilized different approaches to normalization of data, such as cerebellar ratio and whole brain ratio methods, leading to conflicting findings. 2. The authors compared these two methods to test the hypofrontality hypothesis of schizophrenia. 3. Eighteen chronic and medicated DSM-IV schizophrenic patients and 10 healthy controls underwent two SPECT examinations using 99mTc HMPAO as a tracer at baseline and during frontal activation while applying the Wisconsin Card Sorting Test. 4. The hypofrontality hypothesis was supported with both indexes of relative perfusion, although the whole brain ratio method appeared to be more reliable and specific than the cerebellar ratio method. 5. Further studies are required to confirm these preliminary results on the specificity and sensitivity of both methods.

Adolescent↗
PubMed1997

Corpus callosal morphology in treatment-naive pediatric obsessive compulsive disorder.

1. Abnormalities in association circuits have been described in Obsessive Compulsive Disorder (OCD) and may reflect neurodevelopmental abnormalities. Primary and association cortices are topographically mapped in the corpus callosum (CC). The authors hypothesized alterations in CC subdivisions that connect association, but not primary cortices in pediatric OCD. The authors predicted that normal age-related increases in CC area would be absent in OCD. 2. The authors compared the midsagittal magnetic resonance images of 21 psychotropic-naive, nondepressed OCD patients, 7.2-17.7 years, and 21 case-matched healthy controls. Total CC area as well as that of the anterior, middle and posterior genu, anterior and posterior bodies, isthmus, and the anterior, middle and the posterior splenii were measured. 3. All of the CC regions except the isthmus were significantly larger in OCD patients than in controls. CC area correlated significantly with OCD symptom severity but not illness duration. The age-related increase in CC size seen in normal subjects was absent in OCD patients. 4. These findings support theories of abnormal association cortex development in OCD but also suggest possible abnormalities of other primary cortical regions as well.

Adolescent↗
PubMed1997

Magnetic resonance imaging and spectroscopy in offspring at risk for schizophrenia: preliminary studies.

1. Studies of first-degree relatives of persons with schizophrenia provide an opportunity to characterize risk factors for the development of this illness. In this report the authors will provide preliminary data from an ongoing study of neurobiological alterations in the offspring of schizophrenia patients. 2. A series of offspring of schizophrenic patients (OS) were compared with age and sex matched healthy controls (HC) without psychiatric history in first degree relatives on psychiatric, volumetric Magnetic Resonance Imaging (MRI) of whole brain and proton Magnetic Resonance Spectroscopy (1H MRS) evaluations of the ventral prefrontal cortex. 3. Compared with HC group, high risk subjects had reduced left amygdala volume, enlarged third ventricular volume, and smaller overall brain volume. 4. 1H MRS studies showed a trend for decreased NAA/choline ratios in the anterior cingulate region in the OS group as compared to HC subjects. 5. Follow-up studies of these subjects are needed to confirm the predictive value of these measures for future emergence of schizophrenia in subjects at risk for this illness.

Adolescent↗
PubMed1997

Adverse effects of risperidone on eye movement activity: a comparison of risperidone and haloperidol in antipsychotic-naive schizophrenic patients.

Risperidone is a novel and clinically effective atypical antipsychotic medication with a unique biochemical profile. To contrast the neurophysiological effects of this new medication with those of a typical antipsychotic medication, we performed quantitative measurements of saccadic eye movements in a series of antipsychotic-naive schizophrenic patients treated with either risperidone or haloperidol. Patients were tested before and after 1 month of treatment, and a matched group of healthy subjects was tested twice over a similar time interval. Risperidone, but not haloperidol, was associated with prolonged latency and decreased peak velocity and accuracy of saccadic eye movements that was detectable 4 weeks after treatment initiation. The adverse effects of risperidone may be due to the lack of development of acute tolerance to its powerful serotonergic (5-HT2A) antagonism, which could be responsible for the disruption of brainstem physiology in regions controlling saccadic eye movements.

Adult↗
PubMed1997

Hopelessness and first-episode psychosis: a longitudinal study.

Hopelessness has not been adequately studied in first-episode psychotic patients, although it is already present at the early stages, especially in schizophrenic patients. We have studied 96 neuroleptic-naive psychotic patients (49 schizophrenic patients and 47 other non-affective psychotic patients) over a period of 12 months after their first admission. The total score on the Hopelessness Scale (HS) at first admission was higher in the schizophrenic patients, and correlated with younger age and with negative symptoms. High HS scores at baseline predicted poor short-term outcome in schizophrenic patients, as evidenced by worse global functioning at the 12-month follow-up. These correlations were not observed in the other psychoses group. Our results suggest that young, severely affected schizophrenic patients who experience hopelessness might be at higher risk of poor outcome.

Adolescent↗
PubMed1997

Musical hallucinations and musical imagery: prevalence and phenomenology in schizophrenic inpatients.

The discussion of auditory hallucinations in schizophrenia has traditionally focused on verbal auditory hallucinations, or 'voices'. Little attention, on the other hand, has been given to the phenomenon of musical hallucinations. In an effort to characterize the prevalence and phenomenology of musical hallucinations, 100 consecutive schizophrenic inpatients were examined for the presence of musical hallucinations and musical imagery. Sixteen patients responded positively, and were engaged in a more thorough interview. They were then divided into two groups: those with musical hallucinations, and those experiencing musical imagery. This determination was made based on the absence or presence, respectively, of volitional control, hypothesizing that lack of volitional control implies a true hallucinatory experience. When lack of volitional control was compared to the various other aspects of the experience, an association with religious content was demonstrated. Religious musical hallucinations also tended to be experienced as distressing, further supporting the hypothesis that the experience was hallucinatory rather than a product of volitional imagery. A selection of sample case vignettes is presented as well.

Adult↗
PubMed1996

MRI changes in schizophrenia in late life: a preliminary controlled study.

The aim of this pilot study was to compare cerebral changes on magnetic resonance imaging (MRI) scans in elderly schizophrenic subjects with those in psychiatric and normal control subjects. We compared the MRIs of 19 subjects with schizophrenia, 19 age- and gender-matched subjects with recurrent major depression, and 19 age- and gender-matched nonpsychiatric control subjects. Deep white matter hyperintensities (DWMH) in right posterior regions were significantly more prominent in the schizophrenic group than in the two comparison groups. Total ratings of MRI abnormalities were significantly related to age in both the normal control and schizophrenic groups, but not in the depressive group. Age of onset was positively associated with total ratings in the depressive group, but not in the schizophrenic group. Thus, a subset of elderly patients with schizophrenia appear to have cerebral white matter abnormalities; such abnormalities may not be confined to late-onset schizophrenia. Systematic MRI studies of early- and late-onset schizophrenia in late life are needed to resolve this question.

Adolescent↗
PubMed1996

A longitudinal study of EEG sleep in schizophrenia.

Several abnormalities in sleep architecture have been described in schizophrenia. However, the question of whether sleep electroencephalographic (EEG) changes are influenced by treatment and phase of illness remains unclear. To examine the longitudinal stability of sleep data, we compared baseline sleep measures with measures obtained approximately 4 weeks and 1 year after the beginning of treatment in a series of schizophrenic patients. At the 4-week assessment, sleep continuity measures improved significantly; a modest increase in rapid eye movement (REM) latency was seen, but no other changes were found in sleep architecture. At the 1-year assessment, REM latency, REM time, and average automated REM counts increased. No significant changes were seen for slow-wave sleep (SWS) parameters at 1-year follow-up. These findings suggest that SWS parameters are relatively stable during follow-up, while REM parameters seem to change, perhaps in relation to phase of illness and treatment. SWS alterations may, at least in part, reflect more invariant, perhaps trait-related alterations in schizophrenia.

Adult↗
PubMed1996

Nuclear magnetic resonance spectroscopy: new insights into the pathophysiology of mood disorders.

Magnetic Resonance Spectroscopy (MRS) is a novel non-invasive approach for investigation of in vivo brain neurochemistry. In this paper, we review the initial studies conducted in mood disorders. 31P MRS studies have suggested membrane phospholipid and energy metabolism abnormalities in the frontal and temporal lobes of bipolar patients. 1H MRS studies have pointed to increase in choline resonance in the basal ganglia of patients with unipolar and bipolar disorders. Mood disorders are not associated with reductions in N-acetyl-aspartate, unlike schizophrenia and other neuropsychiatric disorders. Both 31P and 1H MRS have begun to be used to investigate the mechanisms of action of ECT. 19F and 7Li MRS offer therapeutically relevant new tools for psychopharmacological investigation, allowing the determination of brain concentrations of psychotropic drugs. Measurement of in vivo brain lithium concentrations may have clinical relevance. While several methodological limitations persist, the noninvasiveness and the unique neurochemical insights provided by MRS offer an excellent opportunity for in vivo investigation of the neurobiology of mood disorders.

Bipolar Disorder↗
PubMed1995

Biological correlates of slow wave sleep deficits in functional psychoses: 31P-magnetic resonance spectroscopy.

Deficits in slow wave sleep (SWS) are consistently seen in schizophrenia and related psychotic disorders. However, the pathophysiological significance of this finding is uncertain. In 19 patients with psychotic illness, sleep and 31P-magnetic resonance spectroscopy (MRS) studies were carried out before the patients began medication treatment. Polysomnographic studies were carried out in 2-3 consecutive nights. MRS studies were performed with a surface coil and a depth-resolved pulse sequence focusing on the dorsal prefrontal cortex. Phosphomonoesters were correlated with visually scored delta and Stage 4 sleep, as well as with automated delta wave counts. An inverse relation was also seen between negative symptoms scores and SWS. The association between decreases brain anabolic processes (reflected by decreased PME) and decreased SWS may be related either to processes of accelerated aging or to developmentally mediated alterations in cortical synaptic pruning, postulated to underlie the pathophysiology of functional psychoses.

Adult↗
PubMed1995

A comparison of stereology and segmentation techniques for volumetric measurements of lateral ventricles in magnetic resonance imaging.

Lateral ventricular volumes were measured on magnetic resonance imaging (MRI) scans by independent raters in 18 subjects (11 psychotic patients and 7 healthy control subjects) with two different approaches: a point-counting stereological (PCS) technique and a computerized technique based on segmentation algorithms. The correlation between the two techniques was very high (r = 0.96), and phantom studies showed good validity for both approaches. These findings and the technical simplicity of the PCS technique support its potential use for MRI morphometric measurements.

Cerebral Ventricles↗
PubMed1995

Sleep EEG changes in psychotic disorders: gender and age effects.

The aim of this study was to examine gender-related differences in electroencephalographic (EEG) sleep in inpatients with psychotic disorders. We investigated the effects of gender and age as well as gender-by-age interactions on sleep continuity, architecture and intranight distributions in 38 male and 23 female patients with functional psychoses. No gender effects were seen for any sleep parameters. However, older psychotic males had less slow-wave sleep than older psychotic females. On the other hand, female psychotic patients showed a significant decline in automated REM counts with age. It is possible that gender-related differences in neurodevelopment and/or aging could account for these findings.

Adolescent↗
PubMed1994

Post-ECT increases in MRI regional T2 relaxation times and their relationship to cognitive side effects: a pilot study.

This pilot study examined the hypothesis that magnetic resonance imaging T2 relaxation times of specific brain regions increase after electroconvulsive therapy (ECT) and that these increases are related to the cognitive side effects of ECT. Six depressed patients undergoing unilateral ECT were studied. The results demonstrate significant post-ECT T2 increases in the right and left thalamus, and suggest a correlation between regional T2 increase and anterograde memory impairment following ECT. These findings are consistent with a post-ECT increase in brain water content (perhaps secondary to a breakdown of the blood-brain barrier) and suggest that this process may be related to the memory impairment following ECT.

Adult↗
PubMed1994

Sleep and suicidality in psychotic patients.

The purpose of the study was to determine whether polysomnographic rapid eye movement (REM) sleep parameters distinguish between psychotic patients with and without a history of suicidal behavior. We examined both hand-scored and automated measures of rapid eye movement (REM) sleep in psychotic patients with and without a history of suicidal ideation or attempts. Patients with suicidal behavior had significantly increased REM activity and time both in the whole night data and in the first REM period. These findings suggest an association between REM sleep abnormalities and suicidal behavior, perhaps related to alteration in serotonergic function.

Adult↗