Measurement of human brain dexfenfluramine concentration by 19F magnetic resonance spectroscopy

OBJECTIVE

The goals of this study were to quantitate the brain concentration of the anorectic drug dexfenfluramine (DF) in human subjects receiving clinical doses of DF and to determine whether human brain DF concentrations approach those reported to cause irreversible neurochemical changes in animals. Each subject's brain DF concentration was measured several times over an extended period of DF treatment to determine whether drug accumulation in the brain would plateau or continue to increase throughout the treatment period.

DESIGN

Fluorine magnetic resonance spectroscopy (19F-MRS) was used to directly detect and quantitate brain levels of the fluorinated drug dexfenfluramine and its active metabolite dex-norfenfluramine (dNF). Patients received 15 mg dexfenfluramine BID for 90 days. 19F-MRS measurements were performed at baseline and at three times during the treatment period.

PARTICIPANTS

Twelve women (age 38-54 years) who were obese, with body mass indices of 28. 4-37.4, but otherwise healthy.

RESULTS

The combined concentration of DF and nDF reached steady-state in the human brain after approximately 10 days of treatment. The steady-state brain concentration averaged approximately 4 microM and did not tend to increase significantly during the 90 day treatment period.

CONCLUSIONS

These results demonstrate that fluorinated drugs can be quantified using 19F MRS at concentrations below 10 microM in the human brain. The time-course data suggest that brain DF concentrations parallel DF plasma pharmacokinetics in humans. Measured brain dexfenfluramine/nor-dexfenfluramine concentrations were well below levels previously found to cause irreversible brain alterations in animals.

Differences in cerebellar blood volume in schizophrenia and bipolar disorder

Brain morphometry has been studied extensively in schizophrenic patients, and among the cortical differences identified two consistent findings are decreased cerebellar vermal volume and increased volume of the fourth ventricle; although contradictory findings are reported as well. Recent cognitive activation studies utilizing PET, SPECT and fMRI have identified both decreased and increased activation in the cerebellum of schizophrenic patients compared with healthy controls. This study used DSC fMRI to map cerebellar blood volume in patients with schizophrenia or bipolar disorder and healthy controls. For all cerebellar regions analyzed, schizophrenic patients had the highest cerebellar blood volume, while bipolars had the lowest blood volume. Morphometric measurements were completed and indicated that the ratio of vermis to whole CBL tissue volume was 24% less for the schizophrenic population than controls, whereas the subjects with bipolar disorder had a ratio that was non-significantly smaller than controls by 19%. Comparison of morphometric data with blood volume data did not reveal any statistically significant correlations among the study groups.

Applications of functional MR imaging to research in psychiatry

Functional MR (fMR) imaging techniques have revolutionized the study of psychiatric illness; however, the clinical utility of fMR imaging studies for these disorders is limited. This article addresses the research applications of fMR imaging to the study of psychiatric disorders. The four psychiatric disorders covered in detail include schizophrenia, obsessive-compulsive disorder, Alzheimer's dementia, and substance abuse. Research findings and implications for future study are discussed with reference to both clinical and technological limitations.

Eye-tracking dysfunction and birth-month weather in schizophrenia

The prevalence of eye-tracking dysfunction (ETD) is significantly elevated in individuals with a diagnosis of schizophrenia and in their nonschizophrenic relatives, suggesting that ETD marks a familial (most likely genetic) risk factor for schizophrenia. Birth in a season with intemperate weather is also a widely reported risk factor for schizophrenia and is particularly marked for the subgroup with no family history of the disorder. This study examined how these two risk factors covaried in 78 patients with a Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.; American Psychiatric Association, 1987) diagnosis of schizophrenia. Eye tracking and birth-month weather were independently assessed. As hypothesized, patients without ETD were significantly more likely to be born in months with intemperate weather (both hot and cold) than either patients with ETD or people in the general population. Etiologic factors associated with severe weather near birth may be important sources of nonfamilial schizophrenia.

Functional magnetic resonance imaging of facial affect recognition in children and adolescents

OBJECTIVE

To examine further the role of the amygdala in the recognition of facial expression in adolescents.

METHOD

Twelve healthy adolescents were studied using functional magnetic resonance imaging technology during a task of facial affect recognition and a visual control task.

RESULTS

All subjects demonstrated a significant increase in signal intensity in the amygdala for the facial expression recognition task.

CONCLUSIONS

The data are consistent with previous work in healthy adult subjects implicating the amygdala as essential for the recognition of fearful facial expression.

Neurologic signs of cerebellar and cortical sensory dysfunction in schizophrenics and their relatives

Previous research has found that both schizophrenics and their relatives have significantly elevated rates of clinical neurologic signs--including 'hard' signs screened to exclude artifacts. The present study examined whether hard signs that indicate relatively localized dysfunction in particular brain regions significantly distinguish schizophrenics and/or their non-schizophrenic relatives from psychiatrically normal controls and patients with other disorders. All patients were diagnosed with DSM-III or DSM-IIIR criteria, using information from structured interviews, supplemented by chart review and family informants. Subjects were administered clinical neurologic examinations by a neurologist blind to diagnosis. The proband sample, composed of 54 schizophrenic or schizoaffective subjects, had a significantly greater proportion of subjects with signs of cerebellar dysfunction than any of the comparison samples, which included: 44 control subjects, 24 patients with substance abuse, 37 patients with bipolar disorder, and 73 of the probands' non-schizophrenic parents and adult siblings. Proportions of both probands and their relatives with signs of dysfunction of sensory cortex were significantly higher than for other groups. Cerebellar and sensory cortical dysfunctions may distinguish different subgroups of schizophrenics and may tend to reflect, respectively, non-familial and familial neuropathological factors.

Dynamic susceptibility contrast MR imaging of regional cerebral blood volume in Alzheimer disease: a promising alternative to nuclear medicine

BACKGROUND AND PURPOSE

The goal of our study was to evaluate the sensitivity and specificity for Alzheimer disease of semiquantitative dynamic susceptibility contrast (DSC) MR imaging as compared with results of qualitative single-photon emission computed tomography (SPECT) in the same patients and with previously published semiquantitative SPECT results.

METHODS

Fifty subjects were studied: 19 patients with probable Alzheimer disease with moderate cognitive impairment, eight mildly impaired patients with possible or probable Alzheimer disease, 18 group-matched elderly healthy comparison subjects, and five elderly comparison patients with psychiatric diagnoses. Relative values of temporoparietal regional cerebral blood volume (rCBV) were measured as a percentage of cerebellar rCBV, and group classification was assessed with logistic regression. The DSC MR imaging results were compared with SPECT scans in these same subjects and with previously published semiquantitative SPECT data.

RESULTS

Temporoparietal rCBV ratios were reduced 20% bilaterally in the patients with Alzheimer disease. Using left and right temporoparietal rCBV as index measures, sensitivity was 95% in moderately affected patients with Alzheimer disease and 88% in patients with mild cases. Specificity was 96% in healthy comparison subjects and in psychiatric comparison subjects. Sensitivity with DSC MR imaging was considerably better than with visual clinical readings of SPECT scans (74% in moderate and 50% in mild Alzheimer disease cases), and was similar to previous published SPECT temporoparietal measurements (90%). Specificity with SPECT was 100% visually and 87% based on previous temporoparietal measurements.

CONCLUSIONS

DSC MR imaging of rCBV is promising as a safe, potentially lower-cost alternative to nuclear medicine imaging for the evaluation of patients with dementia.

Hemispheric asymmetry of frontal and temporal gray matter and age of onset in schizophrenia

BACKGROUND

Investigators have reported lack of normal asymmetry of lateralization in some schizophrenic patients, as measured postmortem and by preference and/or performance. It has been suggested that this lack of asymmetry is related to early onset of schizophrenia. The present study extends the inquiry by magnetic resonance imaging (MRI) measurement of volumetric asymmetry.

METHODS

Hemispheric asymmetry of volume in regional gray matter was examined in 16 schizophrenic patients who had undergone MRI of brain volume.

RESULTS

Low levels of hemispheric asymmetry in the frontal and temporal areas were strongly associated with early onset of schizophrenia, the association with frontal volume being more marked than with temporal volume. No relationship was found in the other brain areas that were scanned. The findings were not artifacts of chronological age, nor of extreme scores in a small sample.

CONCLUSIONS

These findings are consistent with the hypothesis that failure to develop asymmetry is an important component of the pathology underlying some forms of schizophrenia.

Pre- and perinatal complications and risk for bipolar disorder: a retrospective study

BACKGROUND

Many studies have reported that obstetric complications are risk factors for schizophrenia, but few studies have examined whether complications increase risk for bipolar disorder.

METHODS

Bipolar-disorder probands and their adult siblings were diagnosed using DSM-III-R criteria. Obstetrical data from maternal reports were scored, blind to diagnosis, applying published scales that take into account number and severity of complications.

RESULTS

Obstetric complication scores were significantly worse in probands than siblings without mood disorders.

LIMITATIONS

Probands had relatively severe symptoms; research using more heterogeneous samples is needed.

CONCLUSION

Results suggest obstetric complications are etiologically significant in bipolar disorder.

Inverse relationship of perinatal complications and eye tracking dysfunction in relatives of patients with schizophrenia: evidence for a two-factor model

OBJECTIVE

Because both smooth pursuit eye tracking dysfunction and obstetrical complications are significant risk factors for schizophrenia, the authors tested the predictions of a two-factor model of how eye tracking dysfunction and obstetrical complications covary in patients with schizophrenia, their siblings, and comparison subjects.

METHOD

Psychiatric diagnoses, eye tracking dysfunction, and obstetrical complications noted in birth records were independently assessed in 18 patients with schizophrenia, 16 of their siblings without schizophrenia, and 49 comparison subjects with neither personal nor family histories of schizophrenia.

RESULTS

As hypothesized, 1) the combination of eye tracking dysfunction and perinatal obstetrical complications discriminated patients with schizophrenia significantly from subjects without schizophrenia, including siblings of patients with schizophrenia, and 2) eye tracking dysfunction and perinatal obstetrical complications manifested a significant inverse association in the nonschizophrenic siblings of patients with schizophrenia.

CONCLUSIONS

These results support a two-factor model in which obstetrical complications often interact with genetic liability, indicated by eye tracking dysfunction, to produce schizophrenia.

First-episode schizophrenic psychosis differs from first-episode affective psychosis and controls in P300 amplitude over left temporal lobe

BACKGROUND

Schizophrenia is associated with central (sagittal) midline reductions of the P300 cognitive event-related potential and topographic asymmetry of P300, with reduced left temporal voltage. This P300 asymmetry is, in turn, linked to tissue volume asymmetry in the posterior superior temporal gyrus. However, it is unknown whether P300 asymmetry is specific to schizophrenia and whether central and lateral P300 abnormalities are due to chronic morbidity, neuroleptic medication, and/or hospitalization, or whether they are present at the onset of illness.

METHODS

P300 was recorded in first-episode schizophrenia, first-episode affective psychosis, and control subjects (n = 14 per group). Subjects silently counted rare (15%) target tones (1.5 kHz) among trains of standard tones (1.0 kHz). Averages were constructed from brain responses to target tones.

RESULTS

Peak amplitude of P300 and integrated voltage over 300 to 400 milliseconds were significantly different between first-episode schizophrenics and controls over the posterior sagittal midline of the head. First-episode schizophrenics displayed smaller amplitudes over the left temporal lobe than first-episode affective psychotics and controls, but the groups showed no differences over the right temporal lobe.

CONCLUSIONS

Left-sided P300 abnormality in first-episode schizophrenia relative to first-episode affective psychosis and controls suggests that P300 asymmetry is specific to schizophrenic psychosis and present at initial hospitalization. This P300 asymmetry suggests left temporal lobe dysfunction at the onset of schizophrenia.

A quantitative magnetic resonance imaging study of cerebral and cerebellar gray matter volume in primary unipolar major depression: relationship to treatment response and clinical severity

The authors investigated whether there were differences in cerebral and cerebellar gray and white matter volumes in depressed patients compared to controls, and whether this was associated with treatment response to fluoxetine. Brain magnetic resonance images were obtained from 38 unipolar depressed patients and 20 age, gender, and educationally matched comparison subjects. Patients were divided into groups of "responders" and "nonresponders" based on change in 17-item Hamilton Depression Rating Scale (HDRS) after an 8-week standardized trial of fluoxetine, 20 mg/day. There were no group mean differences in cerebral or cerebellar tissue volumes between patients and controls, or responders and nonresponders. For nonresponders to fluoxetine treatment, cerebral and cerebellar gray matter volume, and total cerebellar tissue volume decreased as baseline HDRS increased. The results suggest an association between gray matter volume and severity of illness in nonresponders to fluoxetine treatment.

Basal ganglia choline levels in depression and response to fluoxetine treatment: an in vivo proton magnetic resonance spectroscopy study

We have investigated proton magnetic resonance spectra of the basal ganglia in 41 medication-free outpatients with major depression, prior to starting an 8-week standardized trial of open-label fluoxetine, and 22 matched comparison subjects. Upon completing the trial, depressed subjects were classified as treatment responders (n = 18) or nonresponders (n = 23), based on changes in the Hamilton Depression Rating Scale. Depressed subjects had a lower area ratio of the choline resonance to the creatine resonance (Cho/Cr) than comparison subjects. This statistically significant difference between the depressed subjects and comparison subjects was more pronounced in the treatment responders than in the nonresponders. There were no differences in the relative volumes of gray matter or white matter in the voxel used for proton spectroscopy in depressed subjects relative to comparison subjects. These results are consistent with an alteration in the metabolism of cytosolic choline compounds in the basal ganglia of depressed subjects and, in particular, those who are responsive to fluoxetine.

Age-related reduction in functional MRI response to photic stimulation

Many functional imaging studies have demonstrated age-related alterations in cerebral blood flow during the resting state. However, few studies have addressed possible differences in functional response to cerebral activation. We assessed the response of visual cortex to photic stimulation in 9 normal elderly subjects and 17 normal younger subjects with blood oxygenation level dependent functional magnetic resonance imaging. We found that the amplitude of response in elderly subjects was significantly decreased compared to younger subjects (2.5 +/- 1.0% versus 4.0 +/- 1.6%, p = 0.01), suggesting a reduction in functional activation or an age-related alteration in the coupling of blood oxygenation to focal activation.

Dynamic susceptibility contrast MRI of regional cerebral blood volume in Alzheimer's disease

OBJECTIVE

The purpose of this study was to investigate the potential effectiveness of dynamic susceptibility contrast magnetic resonance imaging (MRI) to discriminate elderly patients with Alzheimer's disease from normal matched comparison subjects.

METHOD

Images of regional cerebral blood volume (CBV) were generated from echo-planar MRI with the dynamic susceptibility contrast method in 13 Alzheimer's disease patients and 13 comparison subjects group-matched on age and gender.

RESULTS

Temporoparietal cerebral blood volume, expressed as a percentage of the cerebellum value, was reduced 17% bilaterally in the patients with Alzheimer's disease. Blood volume in sensorimotor regions was reduced only 8.5% in the patients. Discriminant function analysis based on left and right temporoparietal measures correctly classified 88.5% of the subjects as patients or comparison subjects. Temporoparietal CBV was reduced even in mildly affected Alzheimer's disease patients (Mini-Mental State scores > 24).

CONCLUSIONS

Dynamic susceptibility contrast MRI of regional CBV is promising as a nonradioactive, potentially lower-cost alternative to other functional neuroimaging methods for evaluating Alzheimer's disease.

Proton magnetic resonance spectroscopy of the temporal lobes in schizophrenics and normal controls

Previous research has found structural and functional abnormalities in the temporal lobes of schizophrenic patients, often with greater impairment on the left side. This study applied proton MRS to both right and left temporal lobes of schizophrenic patients and normal control subjects. Reductions in the NAA/Cr ratio were found bilaterally for schizophrenic patients as compared to normal controls, and may be associated with reduced neuronal integrity. These results strengthen the evidence for biochemical abnormalities in the temporal lobes in schizophrenia.

Functional magnetic resonance imaging of schizophrenic patients and comparison subjects during word production

OBJECTIVE

This study was undertaken to test the feasibility of using functional magnetic resonance imaging (MRI) to examine changes in cortical activation in response to verbal tasks in two brain regions.

METHOD

Twelve schizophrenic patients and 11 comparison subjects underwent functional MRI of the frontal and temporal lobes. Stimulus sequences were divided into five 30-second segments by using a task-activation paradigm that alternated between resting and stimulated states. Functional images were collected every 30 seconds by using a gradient echo pulse sequence.

RESULTS

Schizophrenic subjects demonstrated significantly less left frontal activation and greater left temporal activation than comparison subjects during a word fluency task.

CONCLUSIONS

These preliminary data suggest that functional MRI has the sensitivity to detect differences in activation between comparison subjects and schizophrenic patients during higher cortical functions. These findings are in agreement with PET studies that reported reduced left frontal activation during challenge paradigms for the schizophrenic patients.

Temporal lobe proton magnetic resonance spectroscopy of patients with first-episode psychosis

OBJECTIVE

The authors measured the ratio of N-acetyl aspartate (a putative neuronal marker) to creatine-phosphocreatine in patients with first-episode psychosis by using proton magnetic resonance spectroscopy (MRS).

METHOD

Temporal lobe 1H MRS was performed bilaterally on 13 patients with first-episode psychosis and 15 comparison subjects. The N-acetyl aspartate/creatine-phosphocreatine and choline/creatine-phosphocreatine ratios were determined.

RESULTS

The N-acetyl aspartate/creatine-phosphocreatine ratio of the psychotic patients was significantly lower than that of the comparison subjects.

CONCLUSIONS

These preliminary data suggest that abnormalities in temporal lobe N-acetyl aspartate concentration are present early in psychotic illness.

Frontal brain volume and context effects in short-term recall in schizophrenia

In a group of schizophrenic patients, magnetic resonance imaging (MRI) measures of relative frontal brain volume (total frontal volume/total cerebral volume) correlated highly with the capacity to use context as an aid to recall in a verbal memory task. The dorsolateral area of the prefrontal cortex appears to have contributed most to this effect. Recall of simple word lists without contextual features revealed no correlation with relative frontal volume. With increasing contextual organization of the material, correlations between frontal volume and recall scores increased significantly. These findings are consistent with the general proposition that impairment in the use of informational redundancy is a significant component of schizophrenic pathology.

Season of birth and obstetrical complications in schizophrenics

Many studies indicate that both obstetrical complications (OCs) and birth in winter or early spring are risk factors for schizophrenia, but few studies have examined how these risk factors covary in the same subjects. We assessed pre- and perinatal OCs, while blind to diagnosis, using medical data recorded at the time of subjects' births, in 29 probands with DSM-III schizophrenia or schizoaffective disorder and 39 of their unaffected adult sibs. Pre- and perinatal OCs were both significantly more common in probands than sibs. Schizophrenics not born during the winter or early spring had significantly more total and perinatal OCs than schizophrenics born in other months, but did not differ for prenatal OCs. Results indicate that OCs increase risk for schizophrenia, but also suggest the possibility that the impact of OCs on this risk may be affected by season of birth.

Greater hemodynamic response to photic stimulation in schizophrenic patients: an echo planar MRI study

Functional echo planar magnetic resonance imaging (MRI) probably will be of importance in assessing brain abnormalities in psychiatric disorders. The authors used functional MRI to measure the relative magnitude of the change in image signal intensity, reflecting changes in regional neuronal activity caused by photic stimulation, in eight patients with schizophrenia and nine normal comparison subjects. The mean signal intensity change in the primary visual cortex was significantly greater in patients with schizophrenia (mean = 4.6%, SD = 1.5%) than in normal comparison subjects (mean = 3.1%, SD = 1.3%). These results may reflect a variety of factors, including diffuse structural brain changes as well as primary or iatrogenic impairment of mitochondrial function or energy metabolism.

Obstetrical complications and trail making deficits discriminate schizophrenics from unaffected siblings and controls

Numerous studies have reported that both obstetrical complications (OCs) and deficits on the Trail Making Test show elevated prevalences in schizophrenics. Trail Making deficits have also been reported to be more common in schizophrenics' relatives than in controls, suggesting poor Trail Making performance may be a behavioral indicator of a familial risk factor for schizophrenia. Few studies, however, have investigated how these two variables co-vary in samples of schizophrenics and non-schizophrenics. In this study, DSM-III-R diagnoses, OCs noted in birth records, and Trail Making performance were independently assessed in 30 subjects: 9 schizophrenics, 8 of their non-schizophrenic siblings, and 13 comparison subjects with neither a personal nor a family history of schizophrenia. Results supported two key predictions of a two-factor etiologic model of schizophrenia: (a) the combination of perinatal OCs and poor Trail Making performance discriminated schizophrenics extremely well from non-schizophrenics, including their own non-schizophrenic sibs, and (b) perinatal OCs and Trail Making errors manifested a significant inverse association among schizophrenics' non-schizophrenic sibs, but not among other subjects.

Obstetrical complications in patients with bipolar disorder and their siblings

Although indirect evidence suggests that obstetric complications are risk factors for bipolar disorder, few studies have directly addressed this question. Probands with bipolar disorder and their adult siblings were diagnosed according to DSM-III-R criteria by clinicians who had no knowledge of the subjects' obstetrical histories. Hospital records on gestations and births of 16 probands and 20 of their siblings without major mood disorders were scored for obstetric complications without knowledge of diagnosis. The assessment of obstetrical history was based on rating scales that have proved reliable and that reflect the number and severity of complications. Overall complication scores were significantly more severe in probands than siblings. Differences were most marked for perinatal complications.