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Biomedical subjects

M S Keshavan

Publications and source records attributed to M S Keshavan.

At least 55 records · Page 3Linked to original sources
PubMed1999

A.E. Bennett Research Award. Developmental traumatology. Part I: Biological stress systems.

BACKGROUND: This investigation examined the relationship between trauma, psychiatric symptoms and urinary free cortisol (UFC) and catecholamine (epinephrine [EPI], norepinephrine [NE], dopamine [DA]) excretion in prepubertal children with posttraumatic stress disorder (PTSD) secondary to past child maltreatment experiences (n = 18), compared to non-traumatized children with overanxious disorder (OAD) (n = 10) and healthy controls (n = 24). METHODS: Subjects underwent comprehensive psychiatric and clinical assessments and 24 hour urine collection for measurements of UFC and urinary catecholamine excretion. Biological and clinical measures were compared using analyses of variance. RESULTS: Maltreated subjects with PTSD excreted significantly greater concentrations of urinary DA and NE over 24 hours than OAD and control subjects and greater concentrations of 24 hour UFC than control subjects. Post hoc analysis revealed that maltreated subjects with PTSD excreted significantly greater concentrations of urinary EPI than OAD subjects. Childhood PTSD was associated with greater co-morbid psychopathology including depressive and dissociative symptoms, lower global assessment of functioning, and increased incidents of lifetime suicidal ideation and attempts. Urinary catecholamine and UFC concentrations showed positive correlations with duration of the PTSD trauma and severity of PTSD symptoms. CONCLUSIONS: These data suggest that maltreatment experiences are associated with alterations of biological stress systems in maltreated children with PTSD. An improved psychobiological understanding of trauma in childhood may eventually lead to better treatments of childhood PTSD.

Adolescent↗
PubMed1999

A.E. Bennett Research Award. Developmental traumatology. Part II: Brain development.

BACKGROUND: Previous investigations suggest that maltreated children with a diagnosis of posttraumatic stress disorder (PTSD) evidence alterations of biological stress systems. Increased levels of catecholaminergic neurotransmitters and steroid hormones during traumatic experiences in childhood could conceivably adversely affect brain development. METHODS: In this study, 44 maltreated children and adolescents with PTSD and 61 matched controls underwent comprehensive psychiatric and neuropsychological assessments and an anatomical magnetic resonance imaging (MRI) brain scan. RESULTS: PTSD subjects had smaller intracranial and cerebral volumes than matched controls. The total midsagittal area of corpus callosum and middle and posterior regions remained smaller; while right, left, and total lateral ventricles were proportionally larger than controls, after adjustment for intracranial volume. Brain volume robustly and positively correlated with age of onset of PTSD trauma and negatively correlated with duration of abuse. Symptoms of intrusive thoughts, avoidance, hyperarousal or dissociation correlated positively with ventricular volume, and negatively with brain volume and total corpus callosum and regional measures. Significant gender by diagnosis effect revealed greater corpus callosum area reduction in maltreated males with PTSD and a trend for greater cerebral volume reduction than maltreated females with PTSD. The predicted decrease in hippocampal volume seen in adult PTSD was not seen in these subjects. CONCLUSIONS: These data suggest that the overwhelming stress of maltreatment experiences in childhood is associated with adverse brain development.

Adolescent↗
PubMed1999

Corpus callosal signal intensity in treatment-naive pediatric obsessive compulsive disorders.

1. Obsessive compulsive disorder (OCD) is increasingly recognized as a severe, highly prevalent and chronically disabling disorder, emerging during childhood in as many as 80% of cases. The authors previously found significant abnormalities in the region of the corpus callosum (CC) connecting ventral prefrontal cortex and striatum in pediatric OCD patients compared to controls that correlated significantly with OCD symptom severity. We speculated that this abnormality might reflect aberrant myelinization in OCD patients. 2. In order to better characterize the abnormality, the authors examined CC signal intensity (SI), believed to be a reliable index of myelinization of the CC. Lower numbers would indicate a greater concentration of white matter, while higher numbers indicate higher concentrations of gray matter. We compared the SI from midsagittal magnetic resonance images of 21 treatment-naive OCD patients, 7.2-17.7 years, and 21 case-matched healthy controls to examine regional CC signal intensity of the anterior, middle and posterior genu, body, isthmus, and the anterior, middle and the posterior splenii. 3. Mean total genu SI for the patient group (.993 + .006) was significantly less than the total genu SI of controls (.994 + .006) at F(1,37) = 4.73; p = .036. This abnormality in SI was localized to the CC region connecting ventral PFC and striatum, the anterior genu for the OCD group (.991 + .007) which was also less than control (.995 + .007) at F(1,37) = 5.47; p = .025., with no abnormality observed in middle or posterior genu regions. Genu SI was also inversely correlated with OCD symptom severity (r = -.55, p = .013) but not illness duration. Genu SI also correlated positively with genu area (r = .52, p = .020) in OCD patients but not controls. 4. Developmental abnormalities in genu size may arise from abnormalities in myelination in early onset OCD patients. The increased genu myelination observed in OCD patients may alter signal transduction and function of VPFC-striatal association circuits.

Adolescent↗
PubMed1999

Brain maturational processes and delayed onset in schizophrenia.

The central feature of schizophrenia is its onset in adolescence. Although this clinical observation is consistent with the view that schizophrenia may be a neurodevelopmental disorder, debate has focused on when the proposed brain maturational deviations may begin and what might be the nature of such defective development. Conflicting models of this illness (e.g., the early and late neurodevelopmental models) have been proposed. In this paper, we will first review concepts from basic developmental neurobiology pertinent to these issues; we then summarize aspects of the neurobiology of schizophrenia that have a particular bearing on the adolescent onset of this illness. We propose that the schizophrenic syndrome may result from early brain adversity and late maturational processes of brain development interacting with adverse humoral, biochemical, and psychosocial factors during adolescence and early adulthood. The onset of schizophrenia in adolescence may be related to the "plasticity switch" secondary to the peripubertal brain maturational changes, perhaps involving an alteration in glutamate receptor function. This loss of plasticity could result in social and nonsocial cognitive deficits that are central to the pathophysiology of schizophrenia; the vulnerable person may therefore utilize prepubertal processing styles that are insufficient to the adaptive and "gistful" abstraction requirements of adult cognition. Schizophrenia onset might occur in the context of psychosocial developmental challenges to a delayed social cognitive capacity among neurodevelopmentally compromised individuals. We review therapeutic implications as well as testable predictions generated by this model, and discuss research strategies that might further our understanding of the brain maturational abnormalities in schizophrenia.

Adolescent↗
PubMed1999

Prefrontal cortical dysfunction in depression determined by Wisconsin Card Sorting Test performance.

OBJECTIVE: Neuroimaging studies have demonstrated reduced prefrontal cortical blood flow and metabolism in depression, but the neurobehavioral significance of these observations is not yet established. METHOD: The Wisconsin Card Sorting Test, a widely used neuropsychological index of prefrontal cortical function, was administered to 79 patients with major depression who had been unmedicated for at least 28 days, to 47 patients with schizophrenia who had never received antipsychotic medication, and to 61 healthy comparison subjects. RESULTS: Depressed patients demonstrated significant deficits on multiple Wisconsin Card Sorting Test measures compared with healthy individuals. These deficits were correlated with the severity of depression and were less severe than those demonstrated by patients with schizophrenia. CONCLUSIONS: These results provide neuropsychological evidence for significant prefrontal cortical dysfunction in depression.

Adolescent↗
PubMed1999

Managing antipsychotic-induced parkinsonism.

Notwithstanding the advent of clozapine and other 'atypical' antipsychotic agents, the conventional ('typical') antipsychotic agents remain in widespread use. Antipsychotic-induced parkinsonism is a highly prevalent adverse effect that may result in increased morbidity and noncompliance. Bedside examination is generally sufficient for the detection of the onset of parkinsonism and should be carried out frequently in the first 3 months of treatment. In addition to decreasing patient discomfort, monitoring for antipsychotic-induced parkinsonism also serves to identify the minimally effective dosage required for the individual patient. Several strategies are utilised in the management of antipsychotic-induced parkinsonism including dosage reduction, switching to other antipsychotic agents and the use of antiparkinsonian drugs such as anticholinergic agents and amantadine. Anticholinergic agents remain the mainstay of the pharmacological management of antipsychotic-induced parkinsonism in younger patients. Amantadine is a better tolerated agent for elderly patients, with similar efficacy to the anticholinergic agents. The routine use of prophylactic anticholinergics is not recommended and is clearly contraindicated in the elderly. An individualised risk-benefit assessment is necessary for the younger patient in whom prophylactic use of anticholinergic drugs is considered.

Aged↗
PubMed1998

Eye tracking abnormalities in schizophrenia: evidence for dysfunction in the frontal eye fields.

BACKGROUND: Eye tracking deficits are robust abnormalities in schizophrenia, but the neurobiological disturbance underlying these deficits is not known. METHODS: To clarify the pathophysiology of eye tracking disturbances in schizophrenia, we tested 12 first-episode treatment-naive schizophrenic patients and 10 matched healthy individuals on foveofugal and foveopetal step-ramp pursuit tasks. RESULTS: On foveopetal tasks, the initiation of pursuit eye movements was delayed in schizophrenic patients, and their steady-state pursuit gain was reduced particularly at slower target speeds (8 and 16 deg/sec). In foveofugal step-ramp tasks, their primary catch-up saccades were normal in latency and accuracy, but their postsaccadic pursuit in the first 100 msec after the primary catch-up saccade was significantly reduced even relative to their slow steady-state pursuit, especially during and immediately after an acute episode of illness. CONCLUSIONS: These observations indicate that motion-sensitive areas in posterior temporal cortex provide sufficiently intact information about moving targets to guide accurate catch-up saccades, but that the sensory processing of motion information is not being used effectively for pursuit eye movements. Low-gain pursuit after the early stage of pursuit initiation suggests that the use of extraretinal signals about target motion (e.g., anticipatory prediction) only partially compensates for this deficit. The pattern of low-gain pursuit, impaired pursuit initiation, and intact processing of motion information for catch-up saccades but not pursuit eye movements, was consistent in the schizophrenic patients tested at five time points over a 2-year follow-up period, and implicates the frontal eye fields or their efferent or afferent pathways in the pathophysiology of eye tracking abnormalities in schizophrenia.

Adult↗
PubMed1998

A.E. Bennett Research Award. Toward a neurodevelopmental model of of obsessive--compulsive disorder.

BACKGROUND: Neurobiological models for obsessive-compulsive disorder (OCD) have consistently implicated ventral prefrontal cortical and striatal circuits in the pathophysiology of this disorder, but typically have not utilized a developmental framework for conceptualizing the illness. METHODS: We describe an integrated series of neurobiologic studies aimed at testing the hypothesis that neurodevelopmental abnormalities of ventral prefrontal-striatal circuits may be involved in and contribute to the etiology and presentation of the illness. RESULTS: Using studies of oculomotor physiology, we have identified a selective deficit in neurobehavioral response suppression in OCD that may be related to failures in the developmental maturation of frontostriatal circuitry. Magnetic resonance imaging studies showed that treatment-naive pediatric OCD patients had significant volumetric abnormalities in ventral prefrontal cortical and striatal regions but no abnormalities in dorsolateral prefrontal cortex. Severity of OCD symptoms but not illness duration was related to ventral prefrontal cortical and striatal volumes. CONCLUSIONS: Critical neurodevelopmental changes in ventral prefrontal-striatal circuitry may be associated with the initial presentation of OCD, and a developmentally mediated network dysplasia may underlie OCD. Such dysplasia in ventral prefrontal cortical circuits could manifest clinically by disrupting brain functions that mediate ongoing purposive behaviors.

Adolescent↗
PubMed1998

Inter-rater reliability of the neurological examination in schizophrenia.

Neurological Examination Abnormalities (NEA) are prevalent in schizophrenia, but the significance of this is obscured by methodological problems. The Neurological Evaluation Scale (NES), the most widely used structured neurological examination in schizophrenia research, has had limited study of its inter-rater reliability (IRR). An augmented version of the NES was jointly administered (one examiner-rater and one observer-rater) by three pairs of psychiatrists to two populations of patients with idiopathic psychotic disorders. In addition to the ordinal and categorical data yielded by the original NES, continuous data were recorded in one of the series. Reliability analyses of our populations and a previously published study, reveal consistently adequate IRR in 12 of the 26 items assessed, and inconsistently adequate IRR in an additional 11. Consistent with studies using other NEA schedules, IRR was unacceptably low for some items that rely on subjective severity ratings. Certain rare abnormalities, which posed difficulties for the estimation of IRR, are probably not generally useful in the study of schizophrenia. Reliability estimates of continuous, ordinal and dichotomous data were comparable in most cases. We recommend that certain items from the NES be deleted, and that other studies of NEA in psychiatry follow similar procedures before undertaking further analyses.

Adolescent↗
PubMed1998

Delta sleep deficits in schizophrenia: evidence from automated analyses of sleep data.

BACKGROUND: Several, though not all, polysomnographic studies that use conventional visual scoring techniques show delta sleep deficits in schizophrenia. Delta sleep (in particular, > or = 1- to 2-Hz frequency range), mediated by thalamocortical circuits, is postulated to be abnormal in schizophrenia. We investigated whether deficits in delta sleep occur in schizophrenia and whether these are primarily related to the illness or are epiphenomena of previous medication use or illness chronicity. METHODS: We compared 30 unmedicated schizophrenic patients and 30 age- and sex-matched controls for sleep data evaluated by visual scoring as well as automated period amplitude analyses and power spectral analyses. RESULTS: Schizophrenic patients had reduced visually scored delta sleep. Period amplitude analyses showed significant reductions in delta wave counts but not rapid eye movement counts; power spectral analyses showed reductions in delta as well as theta power. Delta spectral power was also reduced in the subset of 19 neuroleptic-naive, first-episode schizophrenic patients compared with matched controls. Delta deficits were more pronounced in the greater than 1- to 2-Hz frequency range. CONCLUSIONS: Delta sleep deficits that occur in schizophrenia may be related to the primary pathophysiological characteristics of the illness and may not be secondary to previous neuroleptic use. Automated sleep quantification by means of period amplitude and power spectral analyses can complement the use of conventional visual scoring for understanding electrophysiological abnormalities in psychiatric disorders.

Adult↗
PubMed1998

Chemical and physiologic brain imaging in schizophrenia.

Technologic advances in functional brain imaging have provided exciting and informative insights into the functional neuroanatomy and neurochemistry of schizophrenia. Using MR spectroscopy, it has been possible to examine in vivo brain metabolism and to relate observed changes to physiological processes occurring at a cellular level. Positron emission tomography and single photon emission computed tomography have revealed disturbances of cerebral blood flow and glucose metabolism in patients with schizophrenia. More recently, these tools have also proved most useful in studying the relative receptor occupancy of typical and atypical antipsychotic medications.

Antipsychotic Agents↗
PubMed1998

Combination treatment with clomipramine and selective serotonin reuptake inhibitors for obsessive-compulsive disorder in children and adolescents.

Medication management of obsessive-compulsive disorder (OCD) has consisted of monotherapy with either clomipramine (CMI) or selective serotonin reuptake inhibitors (SSRIs) such as fluvoxamine, paroxetine, or sertraline. Frequently, OCD patients receiving monotherapy experience low treatment response rates and problematic side effects that may result in discontinuation or noncompliance. This open-label case series presents 7 patients (6 male, 1 female) ages 9 to 23 years with OCD who were effectively treated with combination of CMI plus an SSRI. Treatment effects persisted through 5 to 22 months of follow-up from onset of combination therapy. The drug combination was effective in the 2 patients with OCD and no mood/anxiety comorbidity. Side effects appeared in 5 of 7 patients; cardiovascular side effects were the most common adverse effects. Two patients had prolongation of QTc intervals and 2 developed tachycardia while taking CMI and SSRI combinations. Other risks might include serotonin syndrome, manic switch, insomnia, and possibly headaches, EPS, and sexual dysfunction. Recommendations are made to monitor electrocardiograms, CMI blood concentrations, and vital signs in all cases because SSRIs can increase the blood levels of CMI and/or its active metabolite, desmethylclomipramine (DCMI). CMI could also potentially increase SSRI absorption and/or protein binding. The use of CMI and SSRI combination therapy was found to be more effective compared with their monotherapy in all 7 cases.

Adolescent↗
PubMed1998

Decreased caudate volume in neuroleptic-naive psychotic patients.

OBJECTIVE: Previous studies, mostly involving neuroleptic-treated patients, have suggested enlarged basal ganglia size in schizophrenia. The authors sought to examine basal ganglia volume in neuroleptic-naive psychotic patients. METHOD: Magnetic resonance imaging volumetric studies were conducted in newly diagnosed neuroleptic-naive schizophrenic and non-schizophrenic psychotic patients and in matched healthy comparison subjects. RESULTS: Both patient groups had bilaterally reduced caudate, but not putamen, volumes, compared to the healthy subjects, after adjustment for intracranial volume. CONCLUSIONS: Decreases in caudate volume in newly diagnosed psychotic patients may be related to the primary pathophysiology of these disorders; prior observations of increased caudate volume may reflect effects of neuroleptic treatment.

Adult↗
PubMed1998

The neurologic examination in adult psychiatry: from soft signs to hard science.

Of the proliferating approaches to neuropsychiatric assessment, a relatively neglected technique is the venerable, accessible, noninvasive, and inexpensive neurologic examination. This article organizes and synthesizes the literature on neurological findings in adult psychiatric patients. Problems in conducting and interpreting research in this area are examined, clinically pertinent empirical findings are surveyed, and directions for future investigation are outlined. Most of the "soft signs" can be reliably evaluated, and many have been validated against other techniques. Several psychiatric diagnoses are associated with impaired neurologic performance. Prognosis and treatment selection may also be informed by neurologic findings. The neurologic exam should be regarded as a collection of neurobiologic probes rather than as a single irreducible variable. Future work must better establish interrater and test-retest reliability of individual elements of the neurologic exam in psychiatric populations and focus on developing the clinical utility of individual and combined elements of the neurologic exam.

Adult↗
PubMed1998

Research and treatment strategies in first-episode psychoses. The Pittsburgh experience.

BACKGROUND: Studies of first-episode patients allow investigation of the biological basis of psychotic disorders without the potential confounds of prior treatment and illness chronicity. Prospective studies of this population can clarify the impact of illness course and treatment on neurobiology. METHOD: We summarise preliminary findings from our ongoing magnetic resonance imaging and spectroscopy studies of first-episode schizophrenia patients being conducted prospectively from index evaluations through a period of two years; during this period, patients were treated with either a conventional antipsychotic such as haloperidol, or the atypical risperidone. RESULTS: Baseline neurobiological evaluations in first-episode schizophrenia patients have revealed evidence for structural and functional brain abnormalities consistent with a neurodevelopmental model of this illness. Our preliminary data support the value of risperidone as an antipsychotic drug of first choice among patients with early schizophrenic illness. CONCLUSIONS: Focused studies of first-episode patients have the potential to unravel pathophysiology of schizophrenic illness. Such knowledge is critical for more effective early detection, intervention and even prevention of this enigmatic disorder.

Adolescent↗