Search PubMed⌕ Search

Biomedical subjects

B Toone

Publications and source records attributed to B Toone.

At least 19 recordsLinked to original sources
PubMed2002

Lower prevalence of pre-morbid neurological illness in African-Caribbean than White psychotic patients in England.

BACKGROUND: It has been suggested that the increased incidence of psychosis in African-Caribbeans living in England may be due to illnesses in which social stress plays an important aetiological role. If this is the case, the prevalence of factors associated with psychosis that predate illness onset such as obstetric complications, pre-morbid neurological illness and poor childhood social adjustment may be expected to be lower in African-Caribbean than Whites psychotic patients. METHOD: Details of obstetric complications, pre-morbid neurological illness, and pre-morbid social adjustment were obtained for 337 psychotic patients by patient interview, interviews of mothers and chart review. The proportions of patients with each 'risk factor' in the African-Caribbean (N = 103) and White (N = 184) groups were compared using regression analysis; age, sex, social class, diagnosis and referral status were possible explanatory variables. RESULTS: African-Caribbean patients were less likely to have suffered a pre-morbid neurological disorder than their White counterparts (odds ratio 0.19, 95% CI 0.06-0.61). There was no significant difference in pre-morbid social adjustment or obstetric complications between the two groups, though fewer obstetric complications were reported in the African-Caribbean group (21.5%) than the White group (30.9%). CONCLUSIONS: African-Caribbean patients with psychosis have experienced less pre-morbid neurological illness.

Black or African American↗
PubMed2001

Impaired associative learning in chronic schizophrenics and their first-degree relatives: a study of latent inhibition and the Kamin blocking effect.

The performance of chronic schizophrenic probands (n=21), their first-degree schizotypal (22) and non-schizotypal (19) relatives, and normal controls (24), was measured in two associative learning paradigms, latent inhibition and the Kamin blocking effect. These paradigms assess the effects on learning of initial exposure to other learning contingencies. The normal subjects showed latent inhibition (retarded learning of an association between a burst of white noise and a visually displayed counter increment, if the subject had first been pre-exposed to the white noise without any other consequence) and Kamin blocking (retarded learning of an association between two visual stimuli, if the conditioned stimulus was presented simultaneously with a second, already conditioned stimulus). The schizophrenic probands and both the schizotypal and non-schizotypal relatives were severely impaired in basic associative learning, performing much worse than the normal subjects in the control conditions (i.e. those lacking stimulus pre-exposure of any kind) of both the latent inhibition and the Kamin paradigms and also showed a loss of the normal latent inhibition and Kamin blocking effects. The performance of the three clinically defined groups was statistically indistinguishable. These findings contrast with previous reports of the performance of normal subjects classified as schizotypal by questionnaire, who are not impaired in basic associative learning, and are particularly fast to learn after stimulus pre-exposure. The results question the assumption that high schizotypy, as assessed by questionnaire, is like schizotypy in schizophrenic kin. The severe impairment in basic associative learning in schizophrenic patients and their kin warrants further investigation.

Aged↗
PubMed2001

Structural abnormalities in frontal, temporal, and limbic regions and interconnecting white matter tracts in schizophrenic patients with prominent negative symptoms.

OBJECTIVE: Imaging studies of schizophrenia have repeatedly demonstrated global abnormalities of cerebral and ventricular volumes. However, pathological changes at more local levels of brain organization have not yet been so clearly characterized because of the few brain regions of interest heretofore included in morphometric analyses as well as heterogeneity of patient samples. METHOD: Dual echo magnetic resonance imaging (MRI) data were acquired at 1.5 T from 27 right-handed patients who met DSM-IV criteria for schizophrenia with enduring negative symptoms and from 27 healthy comparison subjects. Between-group differences in gray and white matter volume were estimated at each intracerebral voxel after registration of the images in standard space. The relationship between clinical symptom scores and brain structure was also examined within the patient group. Spatial statistics and permutation tests were used for inference. RESULTS: Significant deficits of gray matter volume in the patient group were found at three main locations: 1) the left superior temporal gyrus and insular cortex, 2) the left medial temporal lobe (including the parahippocampal gyrus and hippocampus), and 3) the anterior cingulate and medial frontal gyri. The volume of these three regions combined was 14% lower in the patients relative to the comparison subjects. White matter deficits were found in similar locations in the left temporal lobe and extended into the left frontal lobe. The patient group showed a relative excess of gray matter volume in the basal ganglia. Within the patient group, basal ganglia gray matter volume was positively correlated with positive symptom scores. CONCLUSIONS: Anatomical abnormalities in these schizophrenic patients with marked negative symptoms were most evident in left hemispheric neocortical and limbic regions and related white matter tracts. These data are compatible with models that depict schizophrenia as a supraregional disorder of multiple, distributed brain regions and the axonal connections between them.

Adult↗
PubMed2000

Schizophrenia, temporal lobe epilepsy and psychosis: an in vivo magnetic resonance spectroscopy and imaging study of the hippocampus/amygdala complex.

BACKGROUND: We have used proton magnetic resonance imaging and spectroscopy to measure hippocampus/amygdala volumes and anterior hippocampal metabolite concentrations (N-acetyl aspartate (NAA), creatine/phosphocreatine and choline) in subjects with temporal lobe epilepsy (TLE), schizophrenia and in normal controls. METHOD: Four groups of right-handed patients were selected: 12 with TLE and psychosis (EP), 12 with TLE and no psychosis (ENP), 26 with schizophrenia, and 38 normal controls. Imaging and spectroscopy were performed with a 1.5T Signa GE scanner. RESULTS: The schizophrenia group showed a significant left-sided reduction in all metabolites. In the epilepsy groups NAA was reduced bilaterally. The NAA reduction in the EP group was greater than in the ENP group, especially on the left, although the result did not reach significance. Total hippocampus/amygdala volumes showed no significant differences in any of the groups when compared with normal controls. When compared with controls significant, specific regional volume reductions were present bilaterally in the EP group and in the left hippocampus/amygdala in schizophrenia. The regional volume reduction found in schizophrenia was also present in EP but not in ENP. CONCLUSION: Spectroscopic abnormalities were more pronounced in the epilepsy groups and were bilateral, and abnormalities in schizophrenia were left sided. Specific regional hippocampus/amygdala volume reductions were more marked in the EP group and were bilateral. Left-sided regional volume reduction identified in the dominant hemisphere of schizophrenics was also present in EP patients, but not in ENP, suggesting that this region in the left temporal lobe may be significant in the aetiology of psychosis. This is further supported by the predominantly left-sided NAA reduction in schizophrenia. High resolution morphometric studies may identify specific regions of the brain associated with the development of psychosis.

Adult↗
PubMed1999

Brain uptake of iomazenil in cirrhotic patients: a single photon emission tomography study.

Brain uptake of 123I-iomazenil was studied in seven cirrhotic patients and eight normal controls using single photon emission computerized tomography. The highest concentration of the ligand was found in the occipital cortex, which corresponds to the brain region with the highest concentration of benzodiazepine receptors. The peak uptake was delayed in patients across all brain regions. The uptake in occipital cortex was higher in low albumin cirrhotics. Patients with low albumin also presented a more delayed peak uptake in occipital cortex and a higher volume of distribution of iomazenil in plasma, compared to patients with normal albumin levels and controls. The changes in brain uptake (delayed peak uptake and increased maximal uptake in occipital cortex) appears to reflect changes in the pharmacokinetics of the ligand, particularly in cirrhotics with low levels of plasma albumin. The curve of brain uptake of the tracer was modelled into a two compartments equation, which seems to provide a practical and reliable method to calculate the slopes of acquisition and decay, time to peak and maximal acquisition.

Adult↗
PubMed1997

Tardive dyskinesia: who is at risk?

Tardive dyskinesia (TD) has been associated with female gender, affective symptoms and good outcome, but also with negative symptoms, cognitive deterioration and deteriorating illness course. Furthermore, antipsychotic medication is thought to be an important risk factor, yet abnormal movements also occur in patients who have never received such medication. We followed 166 subjects with recent onset of psychotic illness and brief previous exposure to antipsychotic medication. Information on 17 previously reported risk factors was available for 125 patients at baseline and, for factors that vary over time, again at follow-up 4 years later (median, 50 months; interquartile range, 29-70). Movement disorder was assessed at follow-up using the Abnormal Involuntary Movement Scale (AIMS). Six noninteracting variables were independently associated with the 4-year risk of TD: male sex (OR, 2.5; 95% CI, 1.1-5.0), age (OR over quartiles at baseline, 1.6; 95% CI, 1.1-2.2), lack of insight at baseline (OR over four categories, 2.0; 95% CI, 1.2-3.2), time on antipsychotics during the follow-up period (OR over quartiles, 2.3; 95% CI, 1.5-3.4), an increase in negative symptoms during the follow-up period (OR over quartiles, 1.7; 95% CI, 1.2-2.5), and alcohol/drug misuse at follow-up (OR, 3.0; 95% CI, 1.3-7.4). The presence of individual risk factors was found to be of little use as a screening test for subsequent clinically relevant TD. Given the absence of a risk factor, however, the probability that an individual would not develop TD was high. These results suggest that two discrete effects may operate to increase the risk of TD, namely an exogenous factor (medication, drugs), and an illness-related factor, the highest risk being conferred by deteriorating illness course in male patients.

Adult↗
PubMed1996

Life events before psychotic episodes: do clinical and social variables affect the relationship?

We have previously used data from the Camberwell Collaborative Psychosis Study to demonstrate a strong relationship between life events and subsequent episodes of schizophrenic, manic and depressive psychoses. In the current paper, we confirmed the robustness of this relationship, which was not vitiated by controlling for clinical and social variables. Thus, the event-onset association was not affected by the type of onset or the number of previous episodes. The influences of social variables, such as social class, ethnicity and marital status, did not seriously diminish the importance of events, although there may be a role for other forms of social disadvantage as reflected in these variables.

Adolescent↗
PubMed1996

Psychopathological syndromes in the functional psychoses: associations with course and outcome.

The aim of this study was to identify underlying dimensions of psychopathology in a cohort of patients with functional psychosis of recent onset, and to examine their prognostic value. Factor analysis of the psychopathological features of 166 consecutively admitted patients with functional psychosis of recent onset revealed seven psychopathological dimensions, which explained 63% of the variance. Five of these seven syndromes bore differential associations with subsequent treatment and illness course, independent of: (i) associations with DSM-III-R diagnosis; (ii) associations with other prognostic factors; and (iii) associations with the baseline values of outcome variables. The most striking associations were shown for an early and insidious onset syndrome with affective flattening, which predicted a more disabled course of illness on three of four outcome dimensions, and which was more common in males and unmarried individuals. A second syndrome, characterized by bizarre behaviour, inappropriate affect, catatonia, and poor rapport showed similar, slightly less striking, associations with illness course, as well as with poor pre-morbid social functioning. A third syndrome, characterized by positive psychotic symptoms was to a lesser degree associated with poorer outcome, whereas a fourth syndrome distinguished by manic symptomatology predicted a more benign illness course. A fifth syndrome identified by lack of insight predicted more time in hospital and admission under a section of the Mental Health Act during the follow-up period. A further finding was that dimensional representations of psychopathological features were considerably more useful than categorical representations (DSM-III-R and ICD-10) as predictors of illness course and treatment decisions.

Adolescent↗
PubMed1995

Psychosis with good prognosis in Afro-Caribbean people now living in the United Kingdom.

OBJECTIVES: To compare the course and outcome of psychotic illness in a group of Afro-Caribbean patients resident in the United Kingdom and a group of white British patients. DESIGN: Cohort study of consecutive admissions followed up for four years. SUBJECTS: 113 patients with psychotic illness of recent onset admitted to two south London hospitals. MAIN OUTCOME MEASURES: Course of illness, history of self harm, social disability, treatment received, and hospital use adjusted for socioeconomic origin. RESULTS: The Afro-Caribbean group spent more time in a recovered state during the follow up period (adjusted odds ratio 5.0; 95% confidence interval 1.7 to 14.5), were less likely to have had a continuous illness (0.3; 0.1 to 0.8), were less at risk of self harm (0.2; 0.1 to 0.8), and were less likely to have been prescribed antidepressant treatment (0.3; 0.1 to 0.9). There were no differences in hospital use, but the Afro-Caribbean group had more involuntary admissions (8.9; 2.1 to 35.6) and more imprisonments over the follow up period (9.2; 1.6 to 52.3). CONCLUSIONS: Afro-Caribbean patients in the United Kingdom have a better outcome after psychiatric illness than do white people. The combination of high incidence and more benign course of illness of psychotic illness in this group may be due, at least in part, to a greater exposure to precipitants in the social environment.

Adolescent↗
PubMed1995

A case of nicotine psychosis?

A woman attempting to stop smoking using transdermal nicotine patches experienced a variety of transient delusions and hallucinations after smoking a cigarette. Various possible explanations are discussed.

Administration, Cutaneous↗
PubMed1995

Increased intracerebral cerebrospinal fluid spaces predict unemployment and negative symptoms in psychotic illness. A prospective study.

BACKGROUND: It has been suggested that the dimensions of cerebral ventricles are a risk factor for poor outcome in psychotic illness. METHOD: A cohort of 140 patients with functional psychoses of recent onset who had undergone CT scanning, were followed up for an average of 46 months and assessed on six dimensions of course and outcome of illness. RESULTS: Left and right sylvian fissure volumes and, to a lesser extent, third ventricular volume predicted negative symptoms and unemployment over the course of follow-up, the latter association being mediated by poor cognitive functioning. There was significant linear trend in risk over the distribution of sylvian fissure volumes in the cohort, and associations were especially evident in schizophrenic patients. No associations were found with global severity of illness, duration of hospital stay, homelessness, or affective symptoms. CONCLUSIONS: These findings support the notion that dimensions of the cerebral ventricles are a continuous risk factor for some measures of outcome in the functional psychoses.

Arousal↗
PubMed1994

Cannabis and acute psychosis.

The Present State Examination was used to assess the psychopathology of 23 psychotic patients who were cannabis positive on urinary screening, and 46 matched drug-free controls. Cases and controls were indistinguishable in terms of psychopathology, DSMIII diagnoses, onset of recent illness, the proportion of first admissions, ethnicity, and socio-economic class, differing only in their histories of substance use. These data suggest that psychosis which develops or recurs in the context of cannabis use does not have a characteristic psychopathology or mode of onset, and is not restricted to a particular ethnic or socio-demographic group. There is thus little evidence to support the validity of 'cannabis psychosis' as a diagnostic entity.

Acute Disease↗
PubMed1994

The influence of life events on the subsequent course of psychotic illness. A prospective follow-up of the Camberwell Collaborative Psychosis Study.

Fifty-nine psychotic patients with acute onset of illness, who had been interviewed about their experience of stressful life events before the episode, were followed up for an average of 42 months. Thirty patients (51%) had experienced a stressful life event in the 3 months immediately before onset (EV+), 29 had not (EV-). In patients with an RDC diagnosis of affective disorder or unspecified functional psychosis, the presence of stressful life events was associated subsequently with milder symptom severity, less time spent in hospital, more treatment for depressive symptoms and less for psychotic symptoms. In schizophrenia, differences were less apparent, but patients with event associated episodes had less need of anti-psychotic maintenance medication over the follow-up period and tended to have spent more time in complete remission. EV+ schizophrenic subjects also had higher morbid risk for schizophrenia in their first degree relatives, and tended to be female and to have less typical symptoms than EV- schizophrenic patients.

Adult↗
PubMed1994

Low birth weight and schizophrenia.

BACKGROUND: Low birth weight has been postulated to be a risk factor for schizophrenia. METHOD: Obstetric history, premorbid adjustment, and cognitive function during admission were assessed in 167 patients with DSM-III schizophrenia or affective psychosis. RESULTS: A birth weight of less than 2500 g was significantly more common in patients with schizophrenia than in those with affective psychosis. Schizophrenic patients as a group had significantly lower mean birth weight, a finding which was particularly marked after controlling for sociodemographic confounders. In schizophrenic men, lower birth weight was highly significantly correlated with poorer premorbid social and cognitive ability, and with impairment of adult cognitive function. CONCLUSIONS: Neurodevelopmental impairment may cause poor foetal growth, and schizophrenia in adult life.

Adolescent↗
PubMed1994

Age at onset, sex, and familial psychiatric morbidity in schizophrenia. Camberwell Collaborative Psychosis Study.

BACKGROUND: Although a genetic component in schizophrenia is well established, it is likely that the contribution of genetic factors is not constant for all cases. Several recent studies have found that the relatives of female or early onset schizophrenic patients have an increased risk of schizophrenia, compared to relatives of male or late onset cases. These hypotheses are tested in the current study. METHOD: A family study design was employed; the probands were 195 patients with functional psychosis admitted to three south London hospitals, diagnosed using Research Diagnostic Criteria (RDC), and assessed using the Present State Examination (PSE). Information on their relatives was obtained by personal interview of the mother of the proband, and from medical records. Psychiatric diagnoses were made using Family History-Research Diagnostic Criteria (FH-RDC), blind to proband information. RESULTS: There was a tendency for homotypia in the form of psychosis within families. The lifetime risk of schizophrenia in the first degree relatives of schizophrenic probands, and the risk of bipolar disorder in the first degree relatives of bipolar probands, were 5-10 times higher than reported population risks. Relatives of female and early onset (< 22 years) schizophrenic probands had higher risk of schizophrenia than relatives of male and late onset schizophrenic probands. However, this effect was compensated in part by an excess of non-schizophrenic psychoses in the relatives of male probands. CONCLUSIONS: These results suggest a high familial, possibly genetic, loading in female and early onset schizophrenia, but do not resolve the question of heterogeneity within schizophrenia.

Adult↗
PubMed1993

Life events and psychosis. Initial results from the Camberwell Collaborative Psychosis Study.

Data from the Camberwell Collaborative Psychosis Study were used to examine the proposition that there is an excess of life events preceding the onset of psychoses of all types. Of 97 patients from the study who had episodes within the past year that were datable, 51 had developed psychotic symptoms from an essentially symptom-free state, 29 had been suffering only from neurotic symptoms, and 17 had experienced a marked exacerbation of psychotic symptoms. DSM-III diagnoses were collapsed into three major groups: 51 cases of schizophrenia; 31 cases of mania; and 14 cases of depressive psychosis. Life-event histories were taken for the six months before onset, and when these were compared with equivalent histories from a psychiatrically healthy sample from the local general population, there was a significant excess of life events, particularly in the three months before onset of psychosis. This was apparent in all groups, and remained even when events were restricted to the independent category. The excess of events began rather earlier than has been found in previous studies. In our view, this study provides some of the strongest evidence for a link between life events and the emergence of psychotic symptoms.

Adolescent↗