Normative neuropsychological test performance: effects of age, education, gender and ethnicity

Normative data on neuropsychological test performance for a sample of 131 adults (ages 18-49) is presented. All subjects were native speakers of English screened for past or present medical, neurological and psychiatric disorders, including substance abuse. A broad-based battery including measures of intellectual skills, memory and learning, receptive and expressive language, auditory and visual information processing and attention, sensory processing, motor skills, and self-reported anxiety and depression was administered. Means, standard deviations and percentile rankings for all tests are reported. Regression analyses were computed to consider the concurrent influence of sociodemographic factors on all tests. Significant effects of age (M=27.1 yrs), education (M=14.6 yrs), gender (58% male), and ethnicity (62% white) were observed for relatively few test scores. Younger age at testing was associated with better continuous performance test scores. Higher education levels were associated with higher vocabulary and reading scores. Males had higher WAIS-R Information scores and faster Finger Tapping scores compared to females Ethnicity was associated with Full-scale IQ, and additional tests with a verbal component, e.g., Boston Naming Tests, and non-verbal component, e.g., Drawing Tests. We conclude that sociodemographic factors infrequently account for more than 10% of the variance for many neuropsychological test scores.

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.

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.

Sex differences in aging of the human frontal and temporal lobes

This study investigated effects of age and sex on regional brain structure in humans, focusing on the frontal and temporal lobes. Hemispheric volumes were obtained from magnetic resonance images (MRIs) of 96 young (53 men, 43 women; aged 18-40 years) and 34 older (17 men, 17 women; aged 41-80) healthy volunteers. Images (5 mm axial spin-echo, repetition time of 3000 msec and echo times of 30 and 80 msec) were resliced along the anterior commissure-posterior commissure (AC-PC) axis to standardize for difference in head tilt, and imported into a computer program where borders of the frontal and temporal lobes were delineated. The program calculated regional brain volumes based on slice data from which CSF was segmented out. An age x sex x hemisphere x region interaction indicated that age-related reductions in brain volume were sexually dimorphic, lateralized, and region specific. Greater decrements in brain volume occurred with age in the frontal lobe than in the temporal lobe. Age-related reductions in both regions were greater in men than in women, demonstrating that sexual dimorphisms in human neuroanatomy are not fixed, but continue to change throughout adulthood. The possibility that gonadal hormones play a role in the promotion and/or prevention of neural atrophy with aging is discussed.

Magnetic resonance imaging in schizophrenia: relationship with clinical measures

Relationships were examined between clinical features of schizophrenia and cerebrospinal fluid (CSF) volume in brain obtained by magnetic resonance imaging (MRI) in a sample of 59 patients. The volumes of the cerebral hemispheres and CSF were measured with a computer program designed to separate reliably neural tissue from CSF. The CSF to cranial volume ratios were related to history, symptom profile and outcome functioning. Earlier age of onset was associated with higher sulcal CSF ratio, r = -0.40. The anatomic measures were unrelated to symptom severity. However, patient subtypes differed in the laterality of measures. Higher left hemispheric ratios were seen in patients with severe negative symptoms, and left predominance of ventricular relative to sulcal ratios was associated with the presence of hallucinations and delusions. The results suggest that while higher CSF is related to earlier age of onset, the clinical symptoms are more related to its lateralization. This is consistent with the hypothesis that schizophrenia is a lateralized brain disease.

Clinical subtypes of schizophrenia: differences in brain and CSF volume

OBJECTIVE

Investigations of the relation of clinical features of schizophrenia to neuroanatomic measures have produced inconclusive results. The purpose of this study was to examine measures of whole-brain volume in men and women and relate them to clinical subtypes of schizophrenia.

METHOD

Magnetic resonance imaging measures of cranial, brain, and ventricular and sulcal CSF volume were examined in 81 patients with schizophrenia (50 men and 31 women), divided into subgroups based on their symptom profiles, and 81 demographically matched healthy comparison subjects.

RESULTS

The men had higher cranial and brain volumes than the women. The patients had smaller cranial and brain volumes than the comparison subjects; they also had higher ventricular CSF volumes and thus higher ventricle-brain ratios (VBRs). Ratio elevations were larger for the female than for the male schizophrenic patients. The patients with predominantly negative symptoms of schizophrenia had higher VBRs and sulcal CSF-brains ratios than the comparison subjects, although the component volumes did not differ. The patients with predominantly Schneiderian symptoms had higher VBRs than the comparison subjects but showed reduced cranial and brain volumes. The paranoid patients had normal VBRs, reduced sulcal CSF-brain ratios, and lower cranial and sulcal CSF volumes.

CONCLUSIONS

The results suggest two patterns of neuroanatomic whole-brain abnormalities that differ in severity according to the relative prominence of negative, Schneiderian, and paranoid symptoms. These patterns may reflect differential involvement of dysgenic and atrophic pathophysiological processes. Sex moderates abnormalities in the neuroanatomic features of schizophrenia.

Neuropsychological deficits in neuroleptic naive patients with first-episode schizophrenia

BACKGROUND

Medication and chronicity have complicated past attempts to characterize the neuropsychological performance of patients with schizophrenia. There have been inconsistencies regarding the pattern, selectivity, and sources of observed deficits. Our objective was to comprehensively examine neuropsychological function in patients with schizophrenia who had never been exposed to neuroleptic medication, and who were experiencing their first episode (FE) of psychosis.

METHODS

Subjects were consecutive recruitments that included 37 patients with FE schizophrenia who were never exposed to neuroleptics. These subjects were compared with 65 unmedicated, previously treated (PT) patients and 131 healthy controls.

RESULTS

The patients groups had nearly identical profiles showing generalized impairment, particularly in verbal memory and learning, attention-vigilance, and speeded visual-motor processing and attention. Verbal memory and learning accounted for most of the variance between patients and controls and removing this effect substantially attenuated all other differences. By contrast, both the FE group and PT group continued to show highly significant deficits in verbal memory and learning after controlling for attention, abstraction, and all other functions. Some functions not typically implicated in schizophrenia (spatial cognition, fine motor speed, and visual memory) were more impaired in the PT group than in the FE group.

CONCLUSIONS

Verbal memory, as a primary neuropsychological deficit present early in the course of schizophrenia, implicates the left temporal-hippocampal system. Neuropsychological evaluations before treatment permit differentiation of primary deficits from changes secondary to medication or chronicity. This is essential for developing a neurobehavioral perspective on schizophrenia.

Cerebral blood flow in schizophrenia: effects of memory processing on regional activation

Regional cerebral blood flow (rCBF) was measured with the 133Xenon clearance technique and a high resolution (254 detectors) scanner during the performance of a verbal and a facial memory task in 18 patients with schizophrenia and 18 sociodemographically matched controls. Patients and controls had comparable resting rCBF, but differed in global and hemispheric rCBF changes induced by the memory tasks. Patients had less global increase, which was relatively higher in the left hemisphere, and this was more pronounced for the verbal task. Although controls showed appropriate laterality changes (L > R for verbal and R > L for facial memory) in the midtemporal region, patients failed to show such a focal pattern. They did not show appropriate laterality change in the midtemporal region, but instead showed such changes in other regions. Patients showed greatest impairment in specificity of verbal recognition performance, and this correlated with severity of hallucinations and delusions. This supports a model of left temporal lobe dysfunction in schizophrenia.

Gender differences in the clinical expression of schizophrenia

Gender differences have been reported for a variety of clinical measures in patients with schizophrenia. Clinical characterization may be helpful in identifying symptom clusters which can then be linked to underlying brain function. In this study 74 men and 33 women meeting DSM-IIIR criteria for schizophrenia were studied off medication and rated on measures of symptom type and severity, as well as premorbid and current function. Men were more severely impaired in ratings of negative symptoms, while positive symptoms were not significantly different. There were also differences in premorbid and current functioning, with women manifesting better social functioning than men.

Facial emotion discrimination: III. Behavioral findings in schizophrenia

Emotional discrimination was studied in patients with schizophrenia (n = 20) and matched controls. Performance of the emotion-discrimination tasks in the schizophrenic patients was impaired, relative to their performance of an age-discrimination task. Performance patterns in the patient group could also be reliably distinguished from those of normal controls. The impairment was associated with the severity of both emotional and nonemotional symptoms specific to schizophrenia, but not with the severity of nonspecific symptoms. The deficit associated with schizophrenia is more marked than that reported for depression (Gur et al., 1992), particularly for the emotion-discrimination tasks, and showed no difference between "happy" discrimination and "sad" discrimination. The main difficulty in patients with schizophrenia is the assignment of emotional valence to neutral faces. The magnitude of the deficit underscores the salience of emotional impairment in schizophrenia, and its relation to cognitive dysfunction in this disorder merits further scrutiny.

Phenomenology and functioning in first-episode schizophrenia

One current view of schizophrenia is that its clinical and functional features show a deteriorating course, particularly for negative symptoms. However, this is difficult to study in chronic patients who have been exposed to pharmacologic treatment and institutionalization. Examining first-episode (FE) patients can help clarify which symptoms are present initially and how the symptom pattern is linked to functioning. We evaluated a sample of 37 FE patients with schizophrenia and compared them to 70 other schizophrenia (OS) patients on standard clinical scales, measures of premorbid functioning, and quality of life. FE patients showed a symptom profile similar to OS patients; in particular, there was no evidence that negative symptoms are less severe in the FE group. Analysis of the clinical data led us to the conclusion that the symptom profile of schizophrenia exists at the outset, that negative symptoms are associated with poor premorbid and current functioning, but that the role of positive symptoms is more complex and may vary in subtypes.

Volunteers for biomedical research. Recruitment and screening of normal controls

We examined the process of accruing healthy control subjects for biomedical research on brain function. Of 1670 responders to newspaper advertising, 23.1% were uninterested when learning more about the studies, and 50.9% of those remaining were found by structured telephone screening to meet exclusionary criteria for having a history of psychiatric, neurologic, or medical disease that might affect brain function. Of 312 volunteers passing the telephone screening who came to an in-person evaluation by a physician and agreed to participate, 49.7% were found to meet exclusionary criteria, and only 157 were admitted to the study. This underscores the importance of attending to the issue of screening and assessment of "normal volunteers." Alternative strategies should be considered for enriching the pool.