Depression in schizophrenia: I. Association with neuropsychological deficits

BACKGROUND

The presence of depression in schizophrenia has been well described with regard to stage and symptoms of illness; however, little is known about the possible etiology.

METHODS

In an effort to advance the understanding of the neurobiology of depression in schizophrenia, we grouped patients with schizophrenia based on their ratings on the 21-item Hamilton Depression Rating Scale. There were 63 patients (35 men, 28 women) in the high (> or = 18) depression group and 81 patients (52 men, 29 women) in the low (< 18) depression group. The groups were compared in demographic, clinical, and eight neuropsychological domains.

RESULTS

The two groups differed in age at onset of illness, severity of delusions, and performance in a single neuropsychological domain: attention. The specific component of impaired attention was vigilance, with poorest performance seen in women with higher depression scores.

CONCLUSION

The presence of specific attentional impairment associated with depressive symptoms in schizophrenia is consistent with the hypothesis of frontal lobe dysfunction in depression, because these regions have been implicated in attentional processes.

P300 subcomponent abnormalities in schizophrenia: I. Physiological evidence for gender and subtype specific differences in regional pathology

BACKGROUND

P300 event-related brain potential (ERP) amplitude is reduced in patients with schizophrenia. Little attention has been paid to gender differences underlying this abnormality, despite clinical differences between male and female schizophrenics. Studies have also largely ignored the fact that the P300 represents the activity of multiple neural generators and have not assessed the separate activity of different subcomponents.

METHODS

Auditory P300 ERPs were recorded from 65 patients (42 male, 23 female) and 48 controls (30 male, 18 female). Positive and negative symptoms were assessed with standardized rating scales, and patients were subtyped as deficit or nondeficit. Five P300 subcomponents were identified using current source density measures: frontal (P3f), bilateral parietal (P3pL, P3pR), and bilateral temporal (P3tL, P3tR).

RESULTS

Three subcomponents (P3tL, P3f, P3pR) were reduced in patients. The left temporal (P3tL) deficit was common across patient groups, but the overall profile of P300 abnormalities varied by gender and deficit/nondeficit status. Women had greater P3tL and P3f decrements; P3pR was abnormal in men. Deficit and nondeficit patients resembled men and women, respectively, independent of gender. P3f and P3tL amplitudes were correlated and unrelated to symptomatology. P3pR was related to Brief Psychiatric Rating Scale score.

CONCLUSIONS

A left temporal abnormality exists in schizophrenia, along with two different profiles of regional pathology, which segregate by gender and deficit/nondeficit status. This supports the hypothesis of two distinct illness subtypes and suggests a physiological basis for phenotypic gender and deficit/nondeficit differences. P300 subcomponent abnormalities may serve as subtype markers. Correlated left temporal and frontal dysfunction is consistent with a frontotemporal neural network disturbance in some schizophrenics. Further investigation of the longitudinal stability and familial inheritance of these subcomponent abnormalities is warranted.

P300 subcomponent abnormalities in schizophrenia: II. Longitudinal stability and relationship to symptom change

BACKGROUND

Reduced amplitude of the P300 event-related brain potential (ERP) is a robust finding in schizophrenia. It remains unclear whether this represents a state or trait abnormality. We previously reported reductions of specific subcomponents of the auditory oddball P300 that were independent of acute symptomatology and were differentially associated with gender and deficit/nondeficit subtype. To clarify the state vs. trait nature of these abnormalities, we reassessed a subset of these patients after a minimum interval of 1 year following initial study.

METHODS

Auditory P300 ERPs were obtained from 18 patients at two time points and compared to baseline normative data recorded from 48 controls. Five P300 subcomponents were identified using current source density measures: frontal (P3f), bilateral parietal (P3pL, P3pR), and bilateral temporal (P3tL, P3tR).

RESULTS

Patients exhibited reduced P300 amplitudes at baseline, including specific reductions of left temporal and right parietal subcomponents. There were no significant changes in P300 amplitudes over time, despite significant improvement in symptomatology, and the parietal subcomponent exhibited persistent impairment. There was, however, a trend toward normalization of the left temporal subcomponent that correlated with change in Brief Psychiatric Rating Scale. There was also a highly significant inverse relationship between changes in frontal P300 subcomponent amplitude and severity of auditory hallucinations (r = -.76).

CONCLUSIONS

The findings support the overall longitudinal stability of P300 deficits in schizophrenia, though there is some state-dependent modulation of these deficits. The relationship between the frontal P300 and hallucinations is consistent with both the cognitive orienting function of this subcomponent and the role of the anterior cingulate as a hypothesized generator of this ERP activity.

Olfactory identification deficits in schizophrenia: correlation with duration of illness

OBJECTIVE

The authors examined the relationship between deficits in olfactory identification and duration of illness in young and elderly patients with schizophrenia.

METHOD

Olfactory identification performance of 38 patients with schizophrenia and 40 normal subjects was compared by using the University of Pennsylvania Smell Identification Test.

RESULTS

The schizophrenic patients demonstrated olfactory deficits relative to the comparison group, and the elderly schizophrenic patients displayed a greater magnitude of olfactory deficit than the younger patients. Independent of normal aging effects and cognitive deficit, patients with schizophrenia showed a strong relationship between olfactory identification scores and duration of illness, which suggests that olfactory abilities decline progressively over the course of the disorder.

CONCLUSIONS

In contrast to other neuropsychological measures that have been reported to be stable over the course of illness, olfactory identification abilities deteriorate steadily in patients with schizophrenia, even for those with relatively recent onset.

PET regional cerebral blood flow change during working and declarative memory: relationship with task performance

Functional and anatomical relationships between working and declarative memory were investigated by contrasting regional cerebral blood flow (rCBF) change during standard working (Wisconsin Card Sorting Test, WCST) and declarative memory (Paired Associate Recognition Test, PART) tasks using identical stimulus-response modalities. The tasks and a resting baseline were administered to 30 participants (16 men, 14 women) during successive 10-min positron emission tomography 15O-water measures of rCBF. For both tasks, rCBF increased over baseline in inferior frontal and occipitotemporal regions, with more consistent dorsolateral prefrontal activation for WCST than PART. Additional orbitofrontal increases and dorsomedial decreases were seen for the PART. Activation patterns diverged when performance was considered. For the WCST, high performers activated dorsolateral and inferior frontal regions, whereas top PART performers activated only the occipitotemporal region. These results suggest operation of a frontotemporal network subserving both types of memory function that becomes more focal as performance increases.

Attentional dysfunctions in neuroleptic-naive and neuroleptic-withdrawn schizophrenic patients and their siblings

This study examined attentional deficits in 44 schizophrenic patients (24 neuroleptic-naive and 20 neuroleptic-withdrawn patients) across changes in medication status and clinical state using a 1-9 continuous performance test (CPT) with distractors. Patients' attentional selectivity scores (A') were unchanged from the off-medication to on-medication testings (on average, 6 months later), despite significant improvement in both positive and negative symptoms. Both patient groups had significantly lower A' scores than 44 matched healthy controls at each testing. The nonschizophrenic siblings (n = 15) of these patients made significantly more errors of omission and commission than healthy controls. The results suggest that attentional deficits, as measured by this CPT, appear to measure stable markers of schizophrenia that may be associated with genetic vulnerability to the illness.

Attentional dysfunctions in neuroleptic-naive and neuroleptic-withdrawn schizophrenic patients and their siblings

This study examined attentional deficits in 44 schizophrenic patients (24 neuroleptic-naive and 20 neuroleptic-withdrawn patients) across changes in medication status and clinical state using a 1-9 continuous performance test (CPT) with distractors. Patients' attentional selectivity scores (A') were unchanged from the off-medication to on-medication testings (on average, 6 months later), despite significant improvement in both positive and negative symptoms. Both patient groups had significantly lower A' scores than 44 matched healthy controls at each testing. The nonschizophrenic siblings (n = 15) of these patients made significantly more errors of omission and commission than healthy controls. The results suggest that attentional deficits, as measured by this CPT, appear to measure stable markers of schizophrenia that may be associated with genetic vulnerability to the illness.

Apolipoprotein E genotype in schizophrenia: frequency, age of onset, and neuropathologic features

Apolipoprotein E (ApoE) genotype has been found to affect the expression of a variety of neuropsychiatric disorders. We determined ApoE genotype frequencies and their relationship to clinical and pathological features in a diverse cohort of individuals with schizophrenia. There were no differences in ApoE genotype frequencies between schizophrenics and controls. However, the ApoE epsilon 4 genotype was associated with a younger age of onset of schizophrenia, and in an elderly subsample, individuals with the epsilon 4 allele more frequently exhibited co-existent dementia and had more neurofibrillary pathology (although none of the cases met criteria for Alzheimer's disease). This examination of ApoE in relation to clinical and neurobiological features of schizophrenia suggests that it modifies the phenotypic expression of the disease.

Neuropsychological evidence supporting a neurodevelopmental model of schizophrenia: a longitudinal study

The stability of neuropsychological performance in schizophrenia and its relationship to clinical change was contrasted between 60 patients with schizophrenia (30 first-episode, 30 previously treated) and 38 healthy controls using a comprehensive neuropsychological battery and clinical scales administered at intake and at a 19-month follow-up. Consistent with the neurodevelopmental model of schizophrenia, patients demonstrated deficits in cognitive performance at initial testing and did not show decline at follow-up. There were no differences in neuropsychological performance over time between first-episode and previously treated patients, nor between male and female patients or controls. As expected, patients improved clinically with treatment with respect to both positive and negative symptoms. First-episode patients improved more on the positive symptoms of hallucination and delusion; male and female patients showed equivalent clinical improvement. Clinical improvement correlated positively with neuropsychological change, with improved negative symptomatology accounting for most of the significant correlations.

Lateralized changes in regional cerebral blood flow during performance of verbal and facial recognition tasks: correlations with performance and "effort"

Functional neuroimaging has been used to investigate neural substrates of mnemonic processes, and cerebral blood flow (CBF) measures have been sensitive to activation with memory tasks. Studies of memory with two-dimensional 133Xenon clearance techniques found that word and face recognition tasks produced contralateral CBF changes in mid-temporal cortical regions. This study replicated the activation paradigm, expanding to the three-dimensional resolution of positron emission tomography (PET). Word and face recognition, and a control baseline task were administered to 19 healthy right-handed volunteers (11 men, 8 women) during successive 10 min PET 15O-water measures of CBF. Quantitative CBF rates were calculated with the arterial input function and the equilibrium model. Redistributions of blood flow were compared across tasks-using both absolute and relative (region/ whole brain) CBF. Replicating the 133Xenon clearance findings, CBF was "appropriately" lateralized during task performance (left-right for words > left-right for faces) in the mid-temporal region. Contrary to predictions, the recognition tasks did not activate expected mesolimbic or prefrontal areas. The task-induced CBF changes also correlated with performance. Bilateral CBF in mid-temporal and parahippocampal gyrus regions of interest correlated with the ability to correctly identify word targets (sensitivity). Left-lateralized CBF in the amygdala and hippocampus correlated with better word sensitivity as well as specificity (ability to correctly reject foils). Complementally, right-lateralized CBF in the parahippocampal gyrus correlated with better face specificity performance. In addition, left-lateralized CBF in the amygdala and right-lateralized CBF in the parahippocampal gyrus and hippocampus correlated with "mental effort" indices (task performance relative to basal ability) for word and face memory tasks, respectively. Thus, whereas this recognition task showed the expected lateralized increase in the mid-temporal region and not in frontal and limbic areas, lateralized activation in some of these areas was associated with better performance. Exploratory analyses on other regions showed lateralized changes in one additional temporal region, the occipital-temporal, and several limbic regions.

PET regional cerebral blood flow change during working and declarative memory: relationship with task performance

Functional and anatomical relationships between working and declarative memory were investigated by contrasting regional cerebral blood flow (rCBF) change during standard working (Wisconsin Card Sorting Test, WCST) and declarative memory (Paired Associate Recognition Test, PART) tasks using identical stimulus-response modalities. The tasks and a resting baseline were administered to 30 participants (16 men, 14 women) during successive 10-min positron emission tomography 15O-water measures of rCBF. For both tasks, rCBF increased over baseline in inferior frontal and occipitotemporal regions, with more consistent dorsolateral prefrontal activation for WCST than PART. Additional orbitofrontal increases and dorsomedial decreases were seen for the PART. Activation patterns diverged when performance was considered. For the WCST, high performers activated dorsolateral and inferior frontal regions, whereas top PART performers activated only the occipitotemporal region. These results suggest operation of a frontotemporal network subserving both types of memory function that becomes more focal as performance increases.

Olfactory identification in elderly schizophrenia and Alzheimer's disease

In the present study we assessed olfactory identification ability using the University of Pennsylvania Smell Identification Test (UPSIT) in 16 elderly patients with schizophrenia (ES), 20 patients with a diagnosis of probable Alzheimer's disease (AD), and 20 healthy elderly controls (EC). Both patient groups exhibited marked deficits in UPSIT performance relative to controls. ES and AD patients with similar levels of general cognitive impairment did not differ on the UPSIT, suggesting that the two disorders may share a common dysfunction in olfactory brain regions. While there have been recent reports of greater olfactory impairment in males, neither patient group exhibited significant gender differences on the UPSIT.

Mesolimbic dopamine D3 receptors and use of antipsychotics in patients with schizophrenia. A postmortem study

BACKGROUND

The pharmacological properties and distribution of a recently cloned member of the dopamine D2 receptor subfamily, the D3 receptor, has led directly to the hypothesis that it may be the target of antipsychotic action.

METHODS

To quantify D3 receptors, we characterized the conditions for selective binding of the radioligand iodine 125-labeled (R)-trans-7-hydroxy-2-[N-propyl-N-(3'-iodo-2'-propenyl)-amino] tetralin ([125I]trans-7-OH-PIPAT) to the human D3 receptor. We then measured by quantitative autoradiography in postmortem tissue the concentration of D3 receptors in the caudal and rostral basal ganglia regions in patients with schizophrenia and control subjects.

RESULTS

We found about 2-fold elevations in the number of D3 receptors in the basal ganglia and ventral forebrain of long-term hospitalized patients with schizophrenia who received no antipsychotic drugs for at least a month before death (n = 7) compared with matched control subjects (n = 15). Patients with schizophrenia receiving antipsychotic drugs less than 72 hours before death (n = 8) had levels similar to those of control subjects. There were no differences in the binding characteristics or affinity of [125I]trans-7-OH-PIPAT binding to D3 receptors between control subjects and patients with schizophrenia.

CONCLUSION

In contrast to the previously detected elevation of D2 and D4 receptor levels in schizophrenia, elevation of D3 receptor levels in limbic striatum and its efferents observed in patients with schizophrenia may be reduced by antipsychotic drugs.

Vulnerability to tardive dyskinesia development in schizophrenia: an FDG-PET study of cerebral metabolism

An understanding of the development of tardive dyskinesia (TD) may require prospective studies assessing the relationship of brain function measures to behavior. This study was undertaken to determine whether predisposition to the development of TD is related to abnormalities of cerebral 18F-labeled 2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) measures in schizophrenia. A group of 42 patients without TD underwent FDG PET scanning for measuring cerebral metabolism as well as neuropsychological evaluation and magnetic resonance imaging. Patients were assessed longitudinally for TD development. Eight patients developed TD within 3 years. They were matched to eight patients without TD. Glucose metabolic rates and region/ whole brain ratios were examined in 38 regions of interest per hemisphere. Whole brain metabolism did not differ between the two groups. However, relative hypermetabolism in temporolimbic, brainstem, and cerebellar regions and hypoactivity in parietal and cingulate gyrus were found in the patients who later developed TD in contrast to those who did not. The groups were matched on clinical measures and had similar neuropsychological and neuroanatomic testing results. Thus, differences in the metabolic activity of specific brain regions are associated with vulnerability to TD development.

Leukocytes and organ-nonspecific autoantibodies in schizophrenics and their siblings: markers of vulnerability or disease?

To determine whether leukocyte counts and organ-nonspecific autoantibodies mark familial vulnerability for schizophrenia and/or the disease itself, we examined 92 patients with schizophrenia and 94 unrelated, demographically balanced, healthy individuals. In addition, for 19 of the probands, one of their nonschizophrenia, full siblings also was recruited. At the time of the blood draw, most probands (87%) had been free of medications for a minimum of 2 weeks and about half were neuroleptic-naive, first-episode patients. Results indicate that a relative lymphopenia in the context of a relative granulocytosis appears to mark familial vulnerability for schizophrenia, whereas an absolute monocytosis appears to mark spectrum manifestations of the clinical phenotype. The former observation is consistent with the hypothesis that the etiology of schizophrenia is immunologically mediated, whereas the latter is consistent with emerging evidence that an inflammatory process is associated with the expression of the disorder. Neither antinuclear antibody nor rheumatoid factor emerged as liability or disease markers.

Relationships between verbal memory performance and the cerebral distribution of fluorodeoxyglucose in patients with schizophrenia

Quantitative resting fluorodeoxyglucose-positron emission tomography scans were performed on 42 patients with schizophrenia. Magnetic resonance imaging-based regions of interest were transposed onto the corresponding positron emission tomography images. Region to whole brain ratios were calculated from the mean regional activity per pixel across both hemispheres (left plus right). Laterality scores were calculated from the difference between the mean activity in homotopic regions of the two hemispheres (left minus right). Subjects were tested contemporaneously with the Logical Memory subtest of the Wechsler Memory Scale. The subtest was scored with modified criteria to provide information about verbal recall, perseverations, and other components of verbal memory. Deficits in recall were associated with increased metabolism in selected regions of the left hemisphere that are known to mediate aspects of verbal memory. The findings support hypotheses suggesting that the left hemisphere is functionally overactive in schizophrenia.

Schizophrenia throughout life: sex differences in severity and profile of symptoms

BACKGROUND

The impact of aging and of gender has been examined in health and disease, but has received limited attention in schizophrenia. A lifespan perspective of gender differences can contribute to an understanding of clinical features and their underlying neurobiological processes.

METHOD

A prospective sample of 272 patients with schizophrenia, divided into four age groups: < 35, 35-65, 65-80 and > 85, was assessed with standardized procedures to measure the composition and severity of symptoms.

RESULTS

Aging was associated with increased severity of symptoms and gender differences were noted. Negative symptoms increased in severity, while some positive symptoms ameliorated with aging. Women were characterized by reduced negative symptoms, and this remained evident until the eighth decade.

CONCLUSIONS

Aging and gender moderate the clinical features of schizophrenia in specific symptom clusters. These effects may give insight into neurobiological substrates of the illness.

Sex differences in neuroanatomical and clinical correlations in schizophrenia

OBJECTIVE

The purpose of this study was to investigate sex differences in relationships between brain and behavior in schizophrenia.

METHOD

Frontal lobe, temporal lobe, and whole brain volumes were obtained from magnetic resonance images of 91 patients with schizophrenia (54 men and 37 women) and 114 healthy comparison subjects (62 men and 52 women). Four independent symptom scales, based on the following symptom clusters, were derived from clinical data: negative, disorganization, Schneiderian hallucinations-delusions, and suspicion-hostility. Regression analyses incorporating the four clinical scales and neuroanatomical volumes were performed to investigate possible interactions between brain region and sex.

RESULTS

Significant interactive effects of sex and frontal lobe volume were found in regression analyses of the disorganization and suspicion-hostility symptom scales. In men, higher frontal lobe volume was associated with milder severity of disorganization but was not correlated with severity of suspicion-hostility. In women, higher frontal lobe volume was associated with more severe disorganization as well as more severe suspicion-hostility. No associations were found between brain volume and severity of negative or Schneiderian symptoms.

CONCLUSIONS

Differences between male and female patients were observed in the relationships between frontal lobe volume and two of the four clinical dimensions examined. These findings suggest that aspects of the neuropathological basis for some symptoms of schizophrenia may be sexually dimorphic.

Course of treatment response in first-episode and chronic schizophrenia

OBJECTIVE

The timing and clinical correlates of symptom change following antipsychotic treatment were examined in first-episode and chronic schizophrenia.

METHOD

The subjects were 36 first-episode schizophrenic patients who had received minimal or no neuroleptics and 34 patients with chronic illness whose neuroleptics had been withdrawn. They were followed for 2 years and assessed with the Scale for the Assessment of Positive Symptoms and the Scale for the Assessment of Negative Symptoms. Treatment decisions during follow-up were made clinically by the treating physicians.

RESULTS

At 6-month follow-up, both the neuroleptic-naive and previously treated patients showed significant improvement in positive symptoms (52% and 44% reductions from baseline, respectively). The previously treated but not the neuroleptic-naive patients also showed a significant reduction in negative symptoms (19% from baseline). A longer duration of illness before baseline assessment and inconsistent treatment during follow-up were independently associated with poorer treatment outcome in terms of positive symptoms in both groups. There were no significant changes on the outcome measures in either group after the 6-month follow-up.

CONCLUSIONS

The results suggest that maximum symptomatic improvement occurs within the first 6 months of treatment and that disease progression may blunt treatment efficacy in both first-episode and chronic schizophrenia.

Cerebral blood flow changes in limbic regions induced by unsolvable anagram tasks

OBJECTIVE

The study addressed the question of whether unsolvable as opposed to solvable cognitive problems activate discrete neuronal systems in the human brain.

METHOD

Twelve healthy humans tried to solve unsolvable anagrams. Solvable anagrams and a resting baseline after each anagram task served as control conditions in a within-subject design. Activation was measured with the equilibrium infusion method by using 15O-labeled water and positron emission tomography, with absolute quantitation of anatomically defined regional cerebral blood flow (CBF).

RESULTS

Compared to rest, both anagram tasks increased activity in frontal and temporal regions. The soluble task condition increased hippocampal activation and decreased mammillary bodies activity, while unsolvable anagrams were associated with increased CBF to the mamillary bodies and amygdala and decreased hippocampal activity.

CONCLUSIONS

A limbic network integrating negative emotion and cognition seems reflected in reciprocal diencephalic and limbic activation with solvable and unsolvable anagrams. Since unsolvable anagrams have been used to induce learned helplessness in humans, this finding may provide an initial step toward clarifying its neural substrate.

Glial fibrillary acidic protein-immunoreactive astrocytosis in elderly patients with schizophrenia and dementia

Clinical and neuropsychological studies of chronically institutionalized patients with schizophrenia indicate that severe cognitive impairment and functional disability in late life are very prevalent. The biological substrates for this dementia remain unknown. While subtle cytoarchitectural and morphometric abnormalities have been described in patients with schizophrenia and interpreted as reflecting aberrant neurodevelopment, postmaturational injury or neurodegeneration associated with gliosis remain as plausible explanations of at least some of the clinical manifestations of schizophrenia. We monitored astrocytosis and neurofibrillary tangle (NFT) formation in 21 elderly patients with schizophrenia (14 with concurrent dementia, 7 without), and in 12 normal and 5 Alzheimer's disease (AD) control cases. Astrocytes in ventromedial temporal, frontal, and calcarine cortices were immunohistochemically identified with monoclonal antibodies directed at glial fibrillary acidic protein (GFAP) and vimentin, and NFTs were labeled with an anti-tau antibody specific for paired helical filaments. There were no increases in GFAP- or vimentin-immunoreactive astrocyte counts, GFAP optical density, or NFT counts for the schizophrenic group as a whole compared to the non-neuropsychiatric group, while both groups differed from AD. When patients with schizophrenia were divided into demented and non-demented subtypes, those with dementia demonstrated significantly greater numbers of GFAP-positive astrocytes than those without dementia. These data may reflect an up-regulation of GFAP in normal astrocytes or the presence of reactive astrocytosis in a subgroup of schizophrenics. In the absence of any diagnostic neuropathological findings in this subgroup, the implications of these observations for the pathogenesis of schizophrenia remain to be determined.

Frontal and temporal lobe brain volumes in schizophrenia. Relationship to symptoms and clinical subtype

BACKGROUND

Quantitative magnetic resonance imaging (MRI) studies demonstrate reduced brain volumes in schizophrenics, but specific structural abnormalities have not been clearly delineated. The structural abnormalities of this disorder are likely to be heterogeneous, consistent with its diverse clinical presentation. To investigate the relationship between structural abnormality and clinical symptoms, we examined regional brain and cerebral spinal fluid (CSF) volumes in a large sample of schizophrenic patients and controls, with patients aggregated into clinical subtypes.

METHODS

Right and left hemisphere frontal and temporal lobe brain and CSF volumes were quantified from 5-mm axial spin-echo MRIs for 71 schizophrenic patients and 77 age- and sex-matched controls. The following four standardized rating scales were used to assess symptom severity: Negative Symptoms, Disorganization, Schneiderian Delusions and Hallucinations, and Suspicion-Hostility. Patients were also subtyped as either deficit or nondeficit on the basis of enduring negative symptoms.

RESULTS

Schizophrenic patients overall exhibited abnormal brain asymmetry, with selective decrease in brain volume in the left temporal and right frontal regions. Left temporal lobe parenchymal volume reduction and CSF volume increase were correlated with the severity of negative symptoms. Consistent with this, the subtype analysis revealed abnormal temporal lobe asymmetry for the deficit subgroup only. Right frontal lobe volume reduction correlated with the duration of illness, independent of symptom severity or schizophrenic subtype.

CONCLUSIONS

Abnormal lateral asymmetry suggests selective structural deficits in schizophrenia, rather than diffusely undifferentiated CNS abnormalities. The pattern of regional abnormalities is related to clinical symptoms, with negative symptoms being associated with left temporal lobe rather than frontal lobe abnormality. This is consistent with suggestions of a temporolimbic prefrontal network abnormality in schizophrenia. Further longitudinal studies are warranted, using higher-resolution MRI technology and gray matter-white matter segmentation to confirm and extend these findings.

Mood effects on limbic blood flow correlate with emotional self-rating: a PET study with oxygen-15 labeled water

Positron emission tomography was used to study the effects of experimentally controlled mood states on cerebral blood flow (CBF), measured with the quantitative equilibrium infusion method and 15O-labeled water. Twenty-seven brain regions in each hemisphere were assessed in 16 normal subjects. CBF and heart rate were measured during happy and sad mood induction, and during two nonemotional control conditions: sex differentiation and resting baseline. Valence-specific effects of mood on CBF were obtained for subcortical, but not for frontal-temporal or control regions. CBF increased in left amygdala and decreased in right amygdala during sad mood relative to the averaged control conditions. These changes correlated with shifts toward negative affect. Correlations were opposite for subcortical (negative affect associated with lower left hemispheric CBF) compared with frontal-temporal cortical regions. Results support limbic involvement in regulating emotional states and suggest some reciprocity between subcortical and frontal-temporal regulation of emotional experience.

Emotional processing in schizophrenia: neurobehavioral probes in relation to psychopathology

The application of neurobehavioral methods in functional neuroimaging can provide useful information on the neurobiology of schizophrenia. This process can be enhanced by using a standard set of procedures to construct 'neurobehavioral probes' which are suitable for functional imaging and provide reliable measures discriminating patients from healthy controls. While such probes are available for cognitive tasks, none has been applied to study emotional processing in schizophrenia. We examined emotional discrimination and experience probes and correlated performance with cognitive and clinical measures. Emotion discrimination tasks and mood induction procedures with happy, sad, and neutral facial expressions were administered to 40 patients with schizophrenia. Neuropsychological testing assessed intellectual, attention, abstraction-flexibility, memory, language, spatial, and sensory-motor functions. Emotional performance was compared to a group of 40 normal subjects. Performance for face discrimination was impaired in patients. There was specific impairment in discrimination of happy expressions. Mood induction was effective in both groups, but diminished in patients, especially for happiness. Poorer performance in emotion discrimination correlated with severity of negative symptoms and bizarre behavior. Hallucinations were associated with more pronounced mood induction effects. Emotion discrimination was also correlated with abstraction, memory, language and spatial tasks, while mood induction effects showed no such associations. Thus, the impairment in discriminating and experiencing valence-specific emotions in schizophrenia relates to symptomatology and neuropsychological functioning. The results encourage the use of the emotion discrimination task and the mood induction procedure as neurobehavioral probes in physiologic neuroimaging studies for investigating the neural substrates of emotion.

Resting cerebral glucose metabolism in first-episode and previously treated patients with schizophrenia relates to clinical features

BACKGROUND

Functional neuroimaging can elucidate brain dysfunction in schizophrenia. The frontal, temporolimbic, and diencephalic regions have been implicated. There is a lack of prospective samples of first-episode and previously treated patients followed up longitudinally.

METHODS

Patients and controls (42 per group) were studied. Positron emission tomography with flurodeoxyglucose, cross-registered with magnetic resonance imaging, measured metabolism. Scales assessed clinical features, premorbid adjustment, and outcome.

RESULTS

There were no differences between groups in whole-brain metabolism or regional ratios or in anterior-posterior gradients, but left midtemporal metabolism was relatively higher in patients. This was pronounced in the negative and Schneiderian and absent in the paranoid subtypes. Higher metabolism and lower relative left hemispheric values were associated with better premorbid adjustment and outcome. A higher subcortical-cortical gradient was noted in first-episode patients.

CONCLUSIONS

There are no resting metabolic abnormalities in any brain region, but abnormal gradients are evident. These vary in subtypes, and laterality is associated with functioning. The results support the hypothesis of temporolimbic disturbance in schizophrenia that is all ready present at the onset of illness.