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Biomedical subjects

V Kumari

Publications and source records attributed to V Kumari.

At least 19 recordsLinked to original sources
PubMed2006

Personality factors correlate with regional cerebral perfusion.

There is an increasing body of evidence pointing to a neurobiological basis of personality. The purpose of this study was to investigate the biological bases of the major dimensions of Eysenck's and Cloninger's models of personality using a noninvasive magnetic resonance perfusion imaging technique in 30 young, healthy subjects. An unbiased voxel-based analysis was used to identify regions where the regional perfusion demonstrated significant correlation with any of the personality dimensions. Highly significant positive correlations emerged between extraversion and perfusion in the basal ganglia, thalamus, inferior frontal gyrus and cerebellum and between novelty seeking and perfusion in the cerebellum, cuneus and thalamus. Strong negative correlations emerged between psychoticism and perfusion in the basal ganglia and thalamus and between harm avoidance and perfusion in the cerebellar vermis, cuneus and inferior frontal gyrus. These observations suggest that personality traits are strongly associated with resting cerebral perfusion in a variety of cortical and subcortical regions and provide further evidence for the hypothesized neurobiological basis of personality. These results may also have important implications for functional neuroimaging studies, which typically rely on the modulation of cerebral hemodynamics for detection of task-induced activation since personality effects may influence the intersubject variability for both task-related activity and resting cerebral perfusion. This technique also offers a novel approach for the exploration of the neurobiological correlates of human personality.

Adult↗
PubMed2006

Fronto-temporal function may distinguish bipolar disorder from schizophrenia.

OBJECTIVES: There is evidence for differential neural alterations within the prefrontal cortex (PFC) in bipolar disorder I (BDI) and schizophrenia that may translate into different cognitive deficits. Our objective was to compare the cognitive profile of stable BDI and schizophrenic patients using neuropsychological tasks which utilize frontal systems but differ in terms of the exact neural circuits and cognitive processes involved. METHODS: We studied 43 patients with BDI, 54 with schizophrenia and 46 matched healthy participants. All participants completed (i) the Wisconsin Card Sorting Test (WCST) which is known to recruit the dorsal and ventral PFC, (ii) the verbal fluency task (VFT), which engages frontal-temporal regions, and (iii) the Stroop Colour Word Test (SWCT) which depends on the integrity of the cingulo-frontal network. A series of multivariate analyses examined differences between the cognitive profiles of BD and schizophrenic patients relative to that of healthy participants controlling for general intellectual ability and gender. RESULTS: Bipolar disorder I patients showed minimal verbal fluency impairment while schizophrenic patients demonstrated marked deficits on this task relative to the control and BDI groups. The two patient groups had comparable performance on the WCST. In the SWCT, schizophrenic patients showed impairment in both congruent and incongruent conditions while BD patients had deficits only in the latter. CONCLUSIONS: Absence of significant verbal fluency abnormalities and by inference dysfunction in the associated fronto-temporal circuitry may distinguish BDI from schizophrenia. Both disorders may show impairment in tasks involving cingulo-frontal networks with evidence of greater cingulate dysfunction in schizophrenia.

Adult↗
PubMed2005

Comparable cortical activation with inferior performance in women during a novel cognitive inhibition task.

Men are hypothesised to perform better than women at tasks requiring cognitive inhibition. The present study applied whole-brain functional magnetic resonance imaging to investigate the neural correlates of cognitive inhibition using a novel task, requiring detection of numbers decreasing in numerical order, in relation to sex. The study involved 19 young healthy subjects (9 men, 10 women). Behavioural sex differences favouring men were found on the inhibition, but not on the automatization (i.e. detection of numbers increasing in numerical order), condition of the task. Significant areas of activation associated with cognitive inhibition included the right inferior prefrontal and bilateral dorsolateral prefrontal cortices, left inferior and superior parietal lobes, and bilateral temporal regions across men and women. No brain region was significantly differently activated in men and women. Our findings demonstrate that (a) cognitive inhibition is dependent on intact processes within frontal and parietal regions, and (b) women show inferior cognitive inhibition despite of comparable activation to men in relevant regions. Equated behavioural performance may elicit sex differences in brain activation.

Adult↗
PubMed2005

Cognitive functioning in siblings discordant for schizophrenia.

OBJECTIVE: The objective of this study was to investigate neuropsychological impairment as a genetically mediated risk indicator for schizophrenia while accounting for prevalence of schizotypy signs/symptoms in siblings. METHOD: Cognitive functioning in 25 individuals with schizophrenia, 25 unaffected siblings and 25 unrelated healthy controls, was assessed using neuropsychological tests of sustained attention, memory and learning, executive function, visual-spatial ability and psychomotor performance. RESULTS: Unaffected siblings demonstrated better performance than patients on some measures of memory and learning and executive function. Patients and siblings demonstrated impaired Full Scale IQ and verbal fluency, otherwise siblings performed similarly to healthy controls. Controlling for differences in IQ, the shared deficit in verbal fluency disappeared. CONCLUSION: Patients with schizophrenia and unaffected siblings (without schizotypy personality disorder) shared a neuropsychological deficit in verbal fluency. This deficit appeared to be mediated by IQ. Deficits, which differentiated patients from controls, may not be inherited and perhaps are related to the manifestation or treatment of schizophrenia.

Adult↗
PubMed2005

Disease, deficit or denial? Models of poor insight in psychosis.

OBJECTIVE: To examine the evidence for the three kinds of aetiological model that dominate the current literature on poor insight in psychosis: clinical models, the neuropsychological model, and the psychological denial model. METHOD: Studies pertaining to one or more of these aetiological models were identified, reviewed and critically evaluated. RESULTS: There is little support for clinical models, partly because they lack testable hypotheses. Several studies reveal a positive relationship between insight and executive function, which may be related to frontal lobe dysfunction. However, the extent to which this relationship is specific and independent of general cognitive impairment remains unclear. There is tentative evidence to support the psychological denial model. Recent data combining the latter two approaches suggest that multiple factors contribute to poor insight. CONCLUSION: Integration of different aetiological models is necessary for a fuller understanding of insight in psychosis. Future research should assess multiple aetiological mechanisms in single investigations.

Attitude to Health↗
PubMed2004

Affective modulation of the startle response in depression: influence of the severity of depression, anhedonia, and anxiety.

BACKGROUND: The amplitude of the startle reflex response is known to be influenced by the concomitant presentation of affect-toned material--if it is positive affect-toned, the reflex is inhibited, and if it is negative affect-toned, the reflex is augmented. Abundant evidence demonstrates the utility of the affect-startle paradigm as a significant tool for measuring both positive and negative emotions. We applied this paradigm to study emotional reactivity in depression, particularly in relation to symptoms of depression, anhedonia, and anxiety. METHODS: Depressed patients (22) and controls (22) were shown a series of film clips, consisting of two clips with positive valence, two with negative valence, and two with relatively neutral valence. The startle response was measured in reaction to the acoustic startle-eliciting stimuli presented three times binaurally during each clip. RESULTS: Highly depressed and anhedonic patients, relative to controls, showed a reduced mood (self-ratings) and a lack of startle modulation in response to affective film clips whereas patients relatively low on depression/anhedonia displayed a reduced mood only with pleasant clips and a normal pattern of affective startle modulation. Anhedonia and depression were highly positively correlated but neither correlated with anxiety. Anxious patients displayed larger reflexes across all clips and showed a reduced mood modulation with pleasant, but not unpleasant, clips. LIMITATIONS: The large majority of patients was medicated with antidepressants which may have influenced the results. CONCLUSIONS. Reactivity to pleasant stimuli is diminished in patients suffering from low levels of depression and/or anhedonia, but reactivity even to unpleasant stimuli seems compromised at high levels of depression and/or anhedonia. Anxiety is associated with hyperstartle responding.

Adult↗
PubMed2004

The relationship of sex hormones and cortisol with cognitive functioning in Schizophrenia.

Gonadal as well as stress hormones have recently been implicated in pathophysiology and sex differences in onset, prognosis and treatment of schizophrenia. The present study investigated the effects of serum levels of oestrogen, progesterone, testosterone and cortisol on neuropsychological functioning and psychopathology in a group of 37 patients (17 women, 20 men) with schizophrenia. Neuropsychological measures included tests of attention, verbal abilities, language, memory, executive functioning, motor and speed of information processing. The results showed that oestrogen and age was associated with low positive symptom scores, and within gender, cortisol predicted poor performance on the information processing domain in men. These findings demonstrate that cortisol, in addition to the commonly reported effects of oestrogen, influences neuropsychological functioning in schizophrenia with differential effects on specific domains of cognitive functioning and underscore the need for further investigation of the modulating role of hormones on neuropsychological functioning in schizophrenia.

Adolescent↗
PubMed2003

Neuroimaging of sexual arousal: research and clinical utility.

The treatment of sexual dysfunction or deviancy requires an understanding of the underlying neural substrates. Neuroimaging techniques offer insight into brain regions involved in sexual arousal and inhibition. The development of robust paradigms has implications for the assessment and treatment of sexual disorder in men and women.

Adolescent↗
PubMed2002

Effects of 10 mg and 15 mg oral procyclidine on critical flicker fusion threshold and cardiac functioning in healthy human subjects.

The critical flicker fusion threshold (CFFT) is thought to index alertness and cortical arousal. Sedative drugs reduce CFFT while psychostimulants increase it. Procyclidine is an anticholinergic that is used to control the extrapyramidal side-effects of antipsychotics in schizophrenia. This study examined the effects of clinically relevant doses of oral procyclidine administration on CFFT and heart rate in two separate experiments (Experiment 1, drug dose: 10 mg, n = 16; Experiment 2, drug dose: 15 mg, n = 12) involving healthy subjects using a double-blind, placebo-controlled, cross-over design. 10 mg procyclidine had no significant effect on CFFT, heart rate or self-ratings of mood, but the 15 mg dose significantly lowered CFFT at 1 h and 2 h after procyclidine administration, increased drowsiness ratings and produced a drop in heart rate. The effects observed in this study may have implications for treatment compliance of schizophrenic patients, choice of antipsychotics, prescribing to patients with heart disease and monitoring of cardiac function under treatment. Further investigations are required to quantify the effects of procyclidine on CFFT and cardiac function in patients with schizophrenia.

Adult↗
PubMed2001

Effects of procyclidine on prepulse inhibition of the acoustic startle response in healthy human volunteers.

RATIONALE: Prepulse inhibition (PPI) of the startle response refers to an attenuation in response to a strong stimulus (pulse) if this is preceded shortly by a weak non-startling stimulus (prepulse). Patients with schizophrenia have repeatedly been found to show reduced PPI when compared to healthy people. Anticholinergic drugs are often used to control extrapyramidal symptoms induced by antipsychotic medication in schizophrenic patients. Antipsychotic medication, in particular with atypical drugs, has been shown to improve a range of cognitive functions and normalize PPI deficits in schizophrenia, whereas anticholinergic drugs disrupt cognitive functions in both normal and schizophrenic populations and also impair PPI in experimental animals. No previous study has investigated the effects of anticholinergic drugs on human PPI. OBJECTIVES: This study determined the effects of procyclidine, an anticholinergic drug, on PPI in healthy male volunteers, employing a double-blind placebo-controlled cross-over design. METHODS: Subjects underwent testing for PPI on two occasions: once after the oral administration of a placebo and once after the oral administration of procyclidine in two separate experiments. Experiment 1 examined the effects of 10 mg procyclidine, whereas experiment 2 examined the effects of 15 mg procyclidine. RESULTS: Procyclidine at a 10 mg dose, as compared to placebo, had no effect on PPI, but caused impairments at a 15 mg dose. In both experiments, procyclidine reduced response amplitude over the pulse-alone trials and heart rate 1-2 h post-administration. CONCLUSIONS: PPI of the human acoustic startle response is modulated by procyclidine. The use of anticholinergics needs to be considered in PPI studies in schizophrenia.

Acoustic Stimulation↗
PubMed2001

Startle response during smoking and 24 h after withdrawal predicts successful smoking cessation.

RATIONALE: The startle response is thought to reflect changes in attentional processes in humans. The startle response shows a number of forms of plasticity, of which prepulse inhibition (PPI) refers to the attenuation of the startle response to a strong sensory stimulus (pulse), when such a pulse is preceded by a stimulus of lower intensity (prepulse). Recent studies have shown that nicotine modulates startle and PPI of the startle reflex in humans and animals. The present study examined individual differences in cognitive benefits obtained from smoking as indexed by startle response and PPI. OBJECTIVES: We investigated, using a within-subjects design, the effects of cigarette smoking via a comparison of baseline and withdrawal measures of startle and PPI in 18 subjects wishing to quit cigarette smoking. The relapse of five of these subjects enabled a between-group comparison of these measures with the successful quitters. METHODS: Startle and PPI were measured on three separate occasions: before quitting, 24 h after quitting and 1 month after quitting. RESULTS: The presence of a high startle response amplitude while subjects were still engaged in their normal smoking patterns (baseline) and the occurrence of a significant drop of startle amplitude in withdrawal relative to baseline factors were found to be predictive of an individual's ability to quit smoking. Changes in PPI were found to reflect these changes in startle amplitude. CONCLUSIONS: The observed response patterns are discussed in terms of individual differences in commitment to quitting and self-dosing to manipulate attentional mechanisms as measured by the acoustic startle response. Furthermore, it is suggested that these specific response profiles may be predictive of the ability to quit smoking.

Adult↗
PubMed2001

Magnetic resonance imaging of the thalamus in first-episode psychosis.

OBJECTIVE: There is some evidence of thalamic abnormalities in schizophrenia. This study investigated thalamic volumes in patients experiencing their first episode of psychosis and nonpsychotic comparison subjects. METHOD: Magnetic resonance imaging scans were obtained for 38 patients and 29 comparison subjects. Patients' symptoms were rated by research psychiatrists using the Positive and Negative Syndrome Scale. RESULTS: Thalamic volumes were smaller in patients than in comparison subjects. There were no significant correlations between thalamic volumes and symptom scores. CONCLUSIONS: Thalamic abnormalities are present close to the onset of psychosis.

Adult↗
PubMed2001

Enhanced startle reactions to acoustic stimuli in patients with obsessive-compulsive disorder.

OBJECTIVE: Anxiety states induced experimentally or occurring naturally potentiate the startle reflex elicited by sudden sensory stimuli in both animals and human beings. The authors investigated whether patients with obsessive-compulsive disorder (OCD) show exaggerated startle reactions to acoustic probes, especially during negative-affect-toned stimuli, compared with healthy subjects. METHOD: Ten patients with OCD and 10 age- and sex-matched comparison subjects were shown a series of film clips. Two of the film clips had positive valence, two had negative valence, and two had relatively neutral valence. The subjects' eyeblink startle response was measured in reaction to startle-eliciting stimuli presented three times binaurally during each film clip. RESULTS: Patients with OCD produced larger startle reflexes and shorter latencies to onset of startle response than the comparison subjects over the entire session. CONCLUSIONS: Patients with OCD were excessively responsive to startle-eliciting stimuli. This effect may be associated with the development or maintenance of OCD.

Acoustic Stimulation↗
PubMed2001

The relationship between prepulse detection and prepulse inhibition of the acoustic startle reflex.

Prepulse inhibition (PPI) of the startle reflex is defined as the attenuation of the startle response to a startling stimulus (pulse), when such a stimulus is briefly preceded by a stimulus of subthreshold intensity (prepulse). PPI is thought to be neither learned nor due to conscious response inhibition, as it occurs at stimulus onset asynchronies (SOAs) too short to enable the activation of a volitional response. The present study explored the latter of these assertions by investigating (a) the degree to which human subjects are able to detect prepulses at SOAs of 30, 60 and 120 ms, and (b) whether such detection is related to inhibition. Startle eyeblink reflex and detection were measured in 39 participants subjected to an acoustic startle paradigm. Results revealed a significant trend in prepulse detection according to SOA, with highest detection rates at the 120-ms SOA (75%). However, trials on which detection occurred did not differ from trials without detection on measures of startle inhibition. This suggests that PPI is independent of awareness of the prepulse.

Acoustic Stimulation↗
PubMed2000

The 10th Biennial Winter Workshop on Schizophrenia. A report.

The 10th Biennial Winter Workshop on Schizophrenia (5-11 February 2000), organized by Drs Tim Crow and Steven Hirsch, attracted a wide range of contributions, not only from European countries, but from all across the world, encompassing clinical, neuropsychological, cognitive, experimental, pharmacological and neuroimaging approaches to enhance the understanding of possible causes, features and the treatments of this illness. The Kongresszentrum, Davos, Switzerland was once again the venue. We present a flavour of the variety of presentations, the news and the views emerging from these presentations, and discuss their implications for further advancement in the field of schizophrenia research.

Education↗
PubMed2000

Prepulse inhibition of the startle response in men with schizophrenia: effects of age of onset of illness, symptoms, and medication.

BACKGROUND: Prepulse inhibition of the startle reflex response refers to the ability of a weak prestimulus to transiently inhibit the response to a closely following strong sensory stimulus. This effect represents an operational index of sensorimotor gating and is found to be deficient in schizophrenia. Prepulse inhibition deficits in schizophrenia seem to be partially normalized by typical antipsychotics and more fully by some atypical antipsychotics. Early onset of schizophrenia, particularly in men, has been associated with abnormal brain maturation, profound neuropsychological deficits, and less responsiveness to antipsychotic medication. We evaluated the effects of the age of onset of illness, current positive and negative symptoms, and the type of medication (typical vs atypical) on prepulse inhibition of the startle response in schizophrenia. METHODS: Thirty-eight male schizophrenic patients and 20 healthy male controls underwent testing for prepulse inhibition of the acoustic startle response. RESULTS: Earlier onset of illness was associated with reduced prepulse inhibition, while adult onset of illness was not. No significant relationships occurred between current symptoms and prepulse inhibition. Patients given typical, but not atypical, antipsychotics exhibited less prepulse inhibition compared with healthy controls. CONCLUSION: Early onset of illness is associated with profound deficits in prepulse inhibition of the startle response in men with schizophrenia.

Acoustic Stimulation↗