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C Pantelis

Publications and source records attributed to C Pantelis.

At least 37 records · Page 2Linked to original sources
PubMed2001

Comorbid non-alcohol substance misuse among people with schizophrenia: epidemiological study in central London.

BACKGROUND: Few epidemiological studies have assessed the extent and nature of comorbid non-alcohol substance misuse in people with schizophrenia in the community in the UK. AIMS: To study the extent and nature of comorbid non-alcohol substance misuse in people with schizophrenia in central London. METHOD: Subjects were identified in an epidemiological census survey of South Westminster. Standardised assessment of each subject included demographic data, ratings of mental state and movement disorder and questioning about drug and alcohol misuse. RESULTS: Individuals with schizophrenia or related psychoses were identified (n=352) and 57 (16%) reported a lifetime history of non-alcohol substance misuse. Age and gender were the main variables relevant to the extent and pattern of misuse. Self-reported non-alcohol substance misuse showed no significant relationship with a range of outcome measures. CONCLUSIONS: The high proportion of subjects reporting non-alcohol substance misuse is comparable with figures from the USA. The reports of lifetime misuse most commonly referred to cannabis, psychostimulants, LSD, opiates and anticholinergics. Misuse was concentrated in those younger than 36 years and was reported more often by males.

Adolescent↗
PubMed2000

An optimized method for estimating intracranial volume from magnetic resonance images.

The accuracy and efficiency of protocols to measure intracranial volume (ICV) from volumetric magnetic resonance imaging (MRI) studies has not been formally analyzed. The ICV of 30 control participants was obtained by tracing every slice of a MRI data set on which the cranial cavity appeared, and compared with estimated ICVs calculated by progressively selecting one of every x slices (i.e., "1-in-x") as a sampling strategy. The reliability and precision of each sampling strategy was then determined. There was virtually no reduction in reliability at the 1-in-10 sampling strategy, with a reliability exceeding 0.999. ICV can be confidently traced using a 1-in-10 sampling strategy, which should result in significant time savings.

Adolescent↗
PubMed2000

Neurobiological findings in early phase schizophrenia.

This paper summarises the available information on MRI-determined hippocampal morphometry in first-episode patients as an illustration of the value and interpretation of findings in the neurobiology of early phase schizophrenia. We report a thin slice (1.5 mm) study of 32 first episode and 39 high risk patients which demonstrated significantly smaller hippocampi (right -9%, left -11%) in first episode patients that were of a similar magnitude to those found in chronic patients (right -10%, left -11%) but non-significant volume reductions in high risk individuals, including the 15 subjects who subsequently developed psychoses. Consideration is given to the implications of these findings, including the possible role of early and later neurodevelopmental influences. We present animal data showing that chronic placental insufficiency, as elicited by uterine artery ligation can give rise to substantial reduction (31%) in hippocampal volumes and reflect on other potentially relevant pathophysiological mechanisms, including those that may occur during the early phases of psychotic illnesses, including their prodromes. Greater attention needs to be paid to the study of early phase psychosis in order to obtain a clearer understanding of the nature and time course of neurobiological changes associated with it. Although there is a growing literature on first episode psychosis, there is a striking dearth of information on the neurobiology of the prodrome.

Animals↗
PubMed2000

Magnetic resonance spectroscopy and schizophrenia: what have we learnt?

OBJECTIVE: Magnetic resonance spectroscopy (MRS) has been increasingly used to investigate the in vivo biochemistry of particular regions of the brain in patients with schizophrenia. We review the literature and discuss the theoretical constructs that form the presumed impetus for these studies in light of the current methodological limitations. Future directions are noted. METHOD: The available published literature in English formed the basis for this review. RESULTS: The results of 31P-MRS have been interpreted as reflecting a relative increase in cell membrane degradation in prefrontal cortical regions at certain phases of schizophrenia. 1H-MRS studies, though less consistent, provide evidence suggestive of a decrease in neuronal cell mass in the hippocampal region, which supports the findings of volumetric studies. Both groups of MRS studies support a neuro-developmental hypothesis of brain dysfunction in schizophrenia. However, current methodological problems limit the reliable interpretation of MRS data. A clear understanding of the methodology and its reliable interpretation is yet to emerge. CONCLUSIONS: MRS remains a research instrument that is yet to be fully utilised in schizophrenia research. A few replicated findings are emerging, although the interpretation of these spectroscopic findings needs to be validated.

Brain↗
PubMed2000

Use of advance information in patients with schizophrenia.

To document possible motor disturbance in schizophrenia, we examined the ability to use advance information (or cues) to plan movements in a sequential button pressing task in 12 Clozapine medicated patients. Programming of movements under various cues revealed that patients with schizophrenia, relative to controls, initiated movements slower to the right than left, providing possible evidence for right hemineglect (left hemisphere dysfunction). Additionally, patients with schizophrenia had difficulty in the initiation of movements in the absence of a cue, suggesting internal cue generation difficulty for movement related to some form of fronto-striatal disturbance. Motor abnormalities were predominantly observed at the level of movement initiation, but not execution, contrary to basal ganglia disorders such as Parkinson's and Huntington's disease.

Adult↗
PubMed2000

Evidence for progression of brain structural abnormalities in schizophrenia: beyond the neurodevelopmental model.

OBJECTIVE: Clinical, neuroimaging, neuropathological and neuropsychological evidence suggests that, in schizophrenia, there is structural and functional disturbance of the hippocampus. The purpose of this paper is to present published findings concerning the nature, timing and course of these putative disturbances of hippocampal function and the pathophysiological mechanisms involved, and to explore whether schizophrenia is a disorder of neurodevelopment, neurodegeneration or a combination of both processes. METHOD: The available cross-sectional and longitudinal evidence for hippocampal involvement in schizophrenia is reviewed and a model of hippocampal involvement in this disorder, which derives from our own cross-sectional and longitudinal hippocampal imaging data, is described. RESULTS: We propose a three-hit model in which an early neurodevelopmental lesion renders the hippocampus vulnerable to further insult later in life during the transition phase to active illness. The available evidence suggests that the left hippocampus is particularly vulnerable during these early stages, while further insult involving the hippocampus bilaterally occurs in those who develop a chronic form of the illness. CONCLUSIONS: Intervention strategies should target the most vulnerable stages of the illness, in particular the transition phase to psychosis, when novel treatments may prevent the illness or ameliorate its effects.

Brain↗
PubMed1999

The three-syndrome model of schizophrenia: meta-analysis of an artefact.

In two recent studies, Smith et al. (Smith, D.A., Mar, C.M., Turoff, B.K., 1998. The structure of schizophrenic symptoms: a meta-analytic confirmatory factor analysis. Schizophr. Res. 31, 57-70) and Grube et al. (Grube, B.S., Bilder, R.M., Goldman, R.S., 1998. Meta-analysis of symptom factors in schizophrenia. Schizophr. Res. 31, 113-120) used meta-analysis to examine the syndromal structure of schizophrenia. A limitation of both these studies is that the nine subscale scores from Andreasen's Scales for Assessment of Positive and Negative symptoms formed the basis of the analyses. These nine ratings, only four of which represent positive symptoms, do not adequately respresent the diversity of positive symptoms. A review of studies that examined the correlation between the individual items of these scales failed to support the classification of symptoms into these nine subgroups. Studies that indicated low numbers of syndromes suffered from one or more of the following limitations: (1) samples that were restricted to chronic schizophrenia, (2) exclusion of many items from analysis, and (3) a poor fit of the symptom model to the data. Studies not limited in these ways indicated the presence of at least 11 major dimensions of schizophrenic symptomatology, not including affective symptoms. It is concluded that the three-syndrome model of schizophrenia is largely an artefact of inadequate measurement at the symptom level.

Artifacts↗
PubMed1999

Comparison of set-shifting ability in patients with chronic schizophrenia and frontal lobe damage.

Neuropsychological studies of patients with schizophrenia have consistently identified deficits on tests sensitive to frontal lobe function. One paradigm that has been widely used is that of attentional set-shifting using the Wisconsin Card Sorting Test (WCST). In the present study, patients with chronic schizophrenia and with frontal lobe lesions were assessed on a computerised set-shifting task that provides a componential analysis of the WCST by distinguishing between intra-dimensional and extra-dimensional set-shifting. Out of 51 patients with schizophrenia, those with high IQ (n =24) were compared with patients with lesions in prefrontal cortex (n = 22) and with normal control subjects (n= 18). These three groups were well matched for age, sex and National Adult Reading Test (NART) IQ. The schizophrenic group showed a significantly higher rate of attrition at the intra-dimensional shift stage of learning compared with the other two groups. At the extra-dimensional shift stage, both the schizophrenic and frontal lesioned groups showed greater attrition than controls. Further, patients with schizophrenia who were able to learn the intradimensional reversal stage required more trials and made significantly more errors at that stage than the other two groups. In comparison with high IQ patients with schizophrenia, those with low IQ performed at a lower level but showed a qualitatively similar pattern of performance, providing further evidence that the set-shifting deficits were not simply explained by any global intellectual decline. Patients with schizophrenia who dropped out at the extradimensional shift stage had higher negative symptom scores compared with patients dropping out at previous learning stages, while patients failing at the intra-dimensional shift stage had lower scores for bradyphrenia (slowness of thought). The results suggest that patients with chronic schizophrenia fail to 'learn set' and are impaired at both set-shifting and concept formation. The relevance of these findings to understanding the nature of prefrontal cortical deficits in chronic schizophrenia is discussed. The implication of these findings to the rehabilitation of these patients is considered.

Adult↗
PubMed1999

Four behavioural syndromes of schizophrenia: a replication in a second inner-London epidemiological sample.

In a previous large epidemiological survey of patients with strictly defined schizophrenia in the London borough of Camden, we extracted four behavioural syndromes (Social withdrawal, Thought disturbance, Anti-social behaviour and Depressed behaviour) by factor analysis of MRC Social Behaviour Schedule (SBS) data. These syndromes had significant differential relationships to symptoms assessed using the Manchester Scale (MS), symptom-derived syndromes, and social functioning variables. A second inner-London epidemiological survey of schizophrenia in South Westminster using identical methodology found the same four behavioural syndromes with identical core component items. The same four behavioural syndromes were extracted, whether applying strict Feighner diagnostic criteria (n=112) or broader DSM-III-R criteria (n=198). The four syndromes extracted from the Feighner positive sample showed relationships to symptoms and social functioning variables similar to those found in the original Camden study. However, the symptom-derived factors were not the same and did not conform to the three recognised symptom-based syndromes of schizophrenia. This successful replication suggests that assessment of the four behavioural syndromes of schizophrenia offers a different perspective on disability and a potentially relevant measure in clinical practice, clinical trials and studies of the neuropsychology and pathophysiology of schizophrenia.

Adult↗
PubMed1999

Hippocampal volume in first-episode psychoses and chronic schizophrenia: a high-resolution magnetic resonance imaging study.

BACKGROUND: It has been proposed that the hippocampus is a potential site for a neurodevelopmental lesion in schizophrenia. While smaller hippocampal volumes have been described in chronic schizophrenia, there have been few magnetic resonance imaging studies in first-episode psychosis. Furthermore, no studies have examined the specificity of this finding to first-episode schizophrenia, compared with first-episode affective psychosis. METHODS: Hippocampal and whole-brain volumes were estimated using high-resolution magnetic resonance imaging in 140 controls, 46 patients with chronic schizophrenia, and 32 patients with first-episode psychosis. RESULTS: Patients with chronic schizophrenia and first-episode psychosis had significantly smaller hippocampal volumes as compared with controls. Within the first-episode group, both patients with schizophrenia/schizophreniform psychosis and those with affective psychosis had smaller left hippocampal volumes as compared with controls. Smaller right hippocampal volumes were associated with age and illness duration in patients with chronic schizophrenia. Hippocampal volumes were not correlated with age of illness onset or medication dosage in either patient group. CONCLUSIONS: These data show that smaller hippocampal volumes are present from the onset of illness. While these findings would support the neurodevelopmental model of schizophrenia, the finding of smaller left hippocampal volume in patients with first-episode schizophrenia and affective psychosis does not support the prediction that smaller hippocampi are specific to schizophrenia. The association of smaller right hippocampal volumes with increased illness duration in chronic schizophrenia suggests either that there is further neurodegeneration after illness onset or that bilateral small hippocampi predict chronicity.

Adult↗
PubMed1999

Tourette's and comorbid syndromes: obsessive compulsive and attention deficit hyperactivity disorder. A common etiology?

Tourette's syndrome (TS), a neuropsychiatric movement disorder that manifests itself in childhood, is often associated with comorbid symptomatology, such as obsessions, compulsions, hyperactivity, distractibility, and impulsivity. Epidemiological studies suggest that a substantial number of TS patients develop clinical levels of obsessive-compulsive disorder (OCD) and/or attention deficit hyperactivity disorder (ADHD). This review aims to provide an integrated account of the three disorders in terms of their comorbidity. Neuroimaging studies suggest that all three disorders involve neuropathology of the basal-ganglia thalamocortical (BGTC) pathways: TS in the sensorimotor and limbic BGTC circuits; OCD in the prefrontal and limbic BGTC pathways; and ADHD in the sensorimotor, orbitofrontal, and limbic BGTC circuits. The pattern of comorbidity and other evidence indicates that the TS gene(s) may be responsible for a spectrum of disorders, including OCD and ADHD, but also that the disorders OCD and ADHD can exist in their own right with their own etiologies.

Attention Deficit Disorder with Hyperactivity↗
PubMed1999

Executive function and attention deficit hyperactivity disorder: stimulant medication and better executive function performance in children.

BACKGROUND: Executive function deficits have been reported repeatedly in children with Attention Deficit Hyperactivity Disorder (ADHD). Stimulant medication has been shown to be effective in improving cognitive performance on most executive function tasks, but neuropsychological tests of executive function in this population have yielded inconsistent results. Methodological limitations may explain these inconsistencies. This study aimed to measure executive function in medicated and non-medicated children with ADHD by using a computerized battery, the Cambridge Neuropsychological Test Automated Battery (CANTAB), which is sensitive to executive function deficits in older patients with frontostriatal neurological impairments. METHODS: Executive function was assessed in 30 children with ADHD: 15 were stimulant medication naive and 15 were treated with stimulant medication. These two groups were compared to 15 age, sex and IQ matched controls. RESULTS: The unmedicated children with ADHD displayed specific cognitive impairments on executive function tasks of spatial short-term memory, spatial working memory, set-shifting ability and planning ability. Impairments were also seen on spatial recognition memory and delayed matching to sample, while pattern recognition memory remained intact. The medicated children with ADHD were not impaired on any of the above executive function tasks except for deficits in spatial recognition memory. CONCLUSIONS: ADHD is associated with deficits in executive function. Stimulant medication is associated with better executive function performance. Prospective follow-up studies are required to examine these effects.

Adolescent↗
PubMed1999

Impairment of olfactory identification in obsessive-compulsive disorder.

BACKGROUND: Olfactory identification ability has been associated with processing in the orbitofrontal cortex (OFC), an area that has been implicated in the pathophysiology of obsessive-compulsive disorder (OCD). Although olfactory sensitivity is normal in patients with OCD, no study has investigated olfactory identification in this disorder. METHODS: A group of 20 subjects with OCD and 23 age- and education-matched controls performed a standardized test of olfactory identification. They also performed computerized tests of spatial memory span, spatial working memory and spatial recognition memory that have been shown previously to be sensitive to cognitive deficits in patients with OCD. RESULTS: Performance on the olfactory identification task, spatial recognition task and spatial span task was significantly worse in the OCD group than controls. CONCLUSIONS: While impairment in spatial cognition is consistent with previous studies of OCD, its significance for brain-behaviour models of OCD is unclear. However, the finding of abnormal olfactory identification in patients with OCD is consistent with the hypothesis that there is a disruption to processing at the level of the OFC in the disorder.

Adult↗
PubMed1999

Abnormalities of internally generated saccades in obsessive-compulsive disorder.

BACKGROUND: We aimed to utilize tests of saccadic function to investigate whether cognitive abnormalities in obsessive-compulsive disorder (OCD) arise from a dysfunction of inhibitory processes or whether they reflect a more general difficulty in guiding behaviour on the basis of an internal representation of task goal. METHODS: Twelve patients with OCD and 12 matched controls performed a visually-guided saccade task, a volitional prosaccade task and an antisaccade task. The latency and gain of saccades was compared between groups for the three saccade tasks. The number of antisaccade errors was also calculated and compared between groups. RESULTS: There was no difference for antisaccade error rates between the groups. The latency of visually guided saccades did not differ between groups, however the latency of both volitional prosaccades and antisaccades was significantly slower in the patients with OCD than in controls. The difference in latency between volitional prosacades and antisaccades, however, was equal between groups. CONCLUSIONS: These results suggest that patients with OCD have an abnormality in guiding behaviour on the basis of an internal representation of the task goal, rather than a problem with inhibiting reflexive behaviour.

Adult↗
PubMed1999

Attention deficit hyperactivity disorder: anxiety phenomena in children treated with psychostimulant medication for 6 months or more.

OBJECTIVE: The intermediate- to long-term use of psychostimulant medication has unclear benefits on the core symptoms of attention deficit hyperactivity disorder (ADHD) and delayed onset affective symptom side effects which can mimic these core ADHD symptoms. 'ADHD and anxiety' has also been associated with a poor response to short-term psychostimulant medication treatment. In addition, it is unclear whether 'ADHD and anxiety' should be defined from the child's and/or the parent's perspective. We propose that anxiety will be increased in children with ADHD who are treated with psychostimulant medication in the intermediate- to long-term who are identified by clinicians as poor responders. METHOD: Twenty children with ADHD who were medicated for 6 months or more and who had ongoing core symptoms of ADHD were compared to 20 age- and IQ-matched children with ADHD who were medication-naïve. Chi-squared tests were performed on the categorical dependent variables and independent t-tests on the dependent continuous variables. RESULTS: Anxiety is significantly increased in children with ADHD treated with psychostimulant medication in the intermediate- to long-term who are noted by clinicians to have ongoing core symptoms of ADHD. This statistically significant finding is evident with both categorical and dimensional measures of anxiety from the child's perspective. CONCLUSIONS: The recognition of anxiety and its management in children with ADHD is generally poorly understood. In this particular group of children with ADHD, anxiety may be a side effect of intermediate- to long-term psychostimulant medication and/or a potential marker for a poor response to intermediate- to long-term psychostimulant medication treatment.

Anxiety↗
PubMed1998

Frontostriatal deficits in unipolar major depression.

Recent accounts of major depression have tended to focus on dysfunction of frontothalamic-striatal reentrant circuits as a possible source of the disorder. Evidence of frontostriatal involvement in unipolar major depression from lesion and neuropsychological studies, and functional and structural imaging studies is examined. The high incidence of depressive symptomatology following left frontal and basal ganglia lesions implicate these as possible sites of dysfunction. Neuropsychological evidence indicates similar deficits in patients with major depression, perhaps with dorsolateral prefrontal deficits most prominent. Structural imaging studies report frontal and basal ganglia (BG) abnormalities particularly in cases of late-age onset depression. Resting state functional imaging studies show deficits in dorsolateral, anterior cingulate (medial frontal), and BG structures. Activation imaging studies show less consistent evidence of dorsolateral deficit, while anterior cingulate deficit is more consistently demonstrated. Variability in findings across studies may reflect differences between subtypes of depression and differences in methodology. Possible involvement of the BG in the psychomotor retardation of depression is examined. It is concluded that, while there is evidence of frontostriatal deficit in major depression, the exact nature of such deficits is uncertain. Issues such as component vs. system dysfunction need to be addressed.

Clinical Trials as Topic↗