Global-local visual processing in schizophrenia: evidence for an early visual processing deficit.

BACKGROUND: Abnormalities in early-stage visual processing might contribute to observed higher neurocognitive deficits in schizophrenia, but to date no clear link has been established. Schizophrenia has been associated with deficits in the magnocellular visual pathway, suggesting a relative bias for processing elemental (local) as opposed to configural (global) aspects of a hierarchical stimulus; however, global-local paradigm studies in schizophrenia have yielded mixed results. METHODS: In the current study, global-local and event-related potential (ERP) procedures were concomitantly used to assess temporal and spatial characteristics of hierarchical visual stimulus processing abnormalities. RESULTS: Patients (n = 24) had slower and less accurate responses to global stimuli than a healthy comparison group (n = 29). They exhibited a marked decrement in N150 ERP amplitude, which correlated with speed of response to global stimuli. They also failed to show an augmented P300 response to local stimuli. CONCLUSIONS: Behavioral and physiological data are consistent and support a global visual processing deficit in schizophrenia. This is manifest at a relatively early stage of visual processing and might relate to physiological disturbances in areas V3/V3a of the extrastriate cortex.

Neuropsychological impairment among manic, depressed, and mixed-episode inpatients with bipolar disorder.

Previous research has demonstrated broad neurobehavioral abnormalities in bipolar affective disorder (cf. G. Cassens, L. Wolfe, & M. Zola, 1990). However, there have been no comparisons of neuropsychological function across patients with manic, depressed, or mixed subtypes. In the present study, 37 manic, 24 mixed-episode, and 25 depressed bipolar I inpatients and 34 control subjects were administered a brief battery of neuropsychological tests. The multivariate and univariate effects of participant group on the neuropsychological measures were uniformly significant (p < .05). Planned contrasts revealed that the bipolar participants performed worse than the controls, and few differences existed between the 3 patient groups. Additionally, the bipolar groups were impaired on 50% of the test battery. These abnormalities were unlikely attributable to differences in psychiatric symptomatology, medical illness, comorbid psychiatric diagnoses, or medication status. Findings imply that acute mood disturbance during bipolar disorder yields significant neurobehavioral dysfunction.

Neuropsychological impairment and psychosis in mania.

Deficits involving executive function, working memory, speed of information processing, and new learning occur in many people with mania. Factors that predict impairment remain poorly understood, but there are indications that psychotic features may correspond with increased risk of neurocognitive dysfunction during manic episodes. The current study examined neuropsychological function in 40 inpatients with bipolar I mania, 24 of whom presented with psychotic features. Compared to a control group, the inpatients showed worse executive function, speed of information processing, new learning, and dexterity. Nonetheless, presence of psychotic features failed to distinguish the inpatients with mania. Thus, psychotic features do not appear to increase neurobehavioral morbidity in people with mania, but presence of mania clearly corresponded with neurobehavioral dysfunction. Implications of these data for clinical practice and our understanding of bipolar disorder are discussed.

Self-reported executive dysfunction, neuropsychological impairment, and functional outcomes in multiple sclerosis.

Although cognitive deficits are common in persons with multiple sclerosis (MS), the relationship between subjective complaints and objective impairment is sometimes obscured. To elaborate this issue, the present study examined the relationship between subjective complaints of dysexecutive syndrome, neuropsychological performance, and self-reported activities of daily living in 42 people with MS and 13 control participants. Regression analyses revealed that subjective complaints of impairment, measured by the Frontal Systems Behavior Scale (FrSBe), emerged as a significant predictor of neuropsychological deficit and poor adaptive function. Accordingly, subjective complaints of dysexecutive function in MS may serve as a potent indicator of cognitive and functional impairment. Implications for research and clinical practice are discussed.

Self-generated learning in people with multiple sclerosis: an extension of Chiaravalloti and DeLuca (2002).

Although memory impairment is common in people with multiple sclerosis (MS), few interventions have been tested to remediate forgetfulness in MS. Chiaravalloti and DeLuca (2002) examined the memory benefit of self-generated encoding over didactic presentation in people with MS and a control group. They found that self-generated encoding enhanced memory of MS patients and a control group alike. The present study extended this finding by examining self-generated encoding in memory-impaired MS patients as well. A control group and MS patients with and without memory impairment learned word-pairs that were either self-generated or didactically presented. All groups remembered more self-generated words than those that were read aloud, and severity of memory impairment failed to moderate this memory benefit. Implications of these findings for cognitive rehabilitation and the nature of memory impairment in MS are discussed.

Comorbid anxiety corresponds with neuropsychological dysfunction in unipolar depression.

INTRODUCTION: Unipolar depressives seem apt to show neuropsychological impairment, particularly involving executive function and memory. Yet, not all depressed patients show such deficits. Major depressive illness shares a high rate of comorbid anxiety disorder, and anxiety disorders also tend to correspond with cognitive difficulties. Consequently, depressed individuals with comorbid anxiety disorders may be inclined to demonstrate greater neuropsychological dysfunction than those without anxiety disorders. METHOD: We compared nonpsychotic depressed inpatients with (n=22) and without comorbid anxiety disorders (n=30) to a group of control subjects (n=38) on a brief but broad battery of neuropsychological tests. Patients were tested during an inpatient admission, and data were collected retrospectively from available records. RESULTS: Both groups of depressed patients showed worse memory function than the controls. Yet, executive dysfunction and psychomotor slowing were specific to the depressed group with comorbid anxiety. The comorbid anxiety group also had more impaired scores than either the nonanxious depressed group or the control group. The depressed group without a comorbid anxiety disorder demonstrated no significant slowing compared to the control group. CONCLUSIONS: Major depressive disorder corresponds with significant memory impairment, regardless of comorbid anxiety disorder. Yet, presence of a comorbid anxiety disorder coincides with deficits involving executive function and psychomotor slowing. Clinical and theoretical relevance of the data is discussed.

Behavioral and physiological findings of gender differences in global-local visual processing.

Hemispheric asymmetries in global-local visual processing are well-established, as are gender differences in cognition. Although hemispheric asymmetry presumably underlies gender differences in cognition, the literature on gender differences in global-local processing is sparse. We employed event related brain potential (ERP) recordings during performance of a global-local reaction time task to compare hemispheric asymmetries and processing biases in adult men (n=15) and women (n=15). Women responded more quickly to local targets while men did not differentially respond to hierarchical stimuli. ERP data indicated that women had P100 responses that were selectively lateralized to the left hemisphere in response to local targets and N150 responses that were smaller for global targets. They also had P300 responses that were greater following local stimuli. The physiological data demonstrate that male-female performance differences arise from biologically based differences in hemispheric asymmetry. Findings are discussed in the context of existing literature regarding gender differences, hemispheric specialization, and the role of stimulus characteristics.

Self-generated learning in people with multiple sclerosis.

Memory impairment is among the most common cognitive deficits in people with multiple sclerosis (MS). To remediate this problem, recent research has evaluated the benefits of self-generated encoding. These nascent investigations reveal that people with MS who have mild memory impairment demonstrate a significant memory benefit from self-generated encoding compared with didactic learning. To extend prior research, the present experiment included MS patients with moderate-severe, rather than just mild, memory impairment. Additionally, the experiment evaluated whether self-generated encoding improves memory for activities of daily living instead of abstract words. Specifically, the experiment determined whether self-generated encoding enhanced memory for names, appointments, and object locations. In agreement with and extending prior research, MS patients remembered more information if it was self-generated rather than didactically presented, and this finding occurred despite moderate-severe memory impairment. Furthermore, compared with didactic encoding, self-generation enhanced recall of activities of daily living. Implications of these findings for cognitive rehabilitation and the nature of memory impairment in MS are discussed.

Global-local visual biases correspond with visual-spatial orientation.

Within the past decade, numerous investigations have demonstrated reliable associations of global-local visual processing biases with right and left hemisphere function, respectively (cf. Van Kleeck, 1989). Yet the relevance of these biases to other cognitive functions is not well understood. Towards this end, the present research examined the relationship between global-local visual biases and perception of visual-spatial orientation. Twenty-six women and 23 men completed a global-local judgment task (Kimchi and Palmer, 1982) and the Judgment of Line Orientation Test (JLO; Benton, Sivan, Hamsher, Varney, and Spreen, 1994), a measure of visual-spatial orientation. As expected, men had better performance on JLO. Extending previous findings, global biases were related to better visual-spatial acuity on JLO. The findings suggest that global-local biases and visual-spatial orientation may share underlying cerebral mechanisms. Implications of these findings for other visually mediated cognitive outcomes are discussed.

Practice effects on the WAIS-III across 3- and 6-month intervals.

Fifty-one participants (age M = 24.6; education M = 14.4 years) were administered the Wechsler Adult Intelligence Scale - Third Edition (WAIS-III) at baseline and at an interval of either 3 or 6 months later. Full Scale IQ (FSIQ), Verbal IQ (VIQ), Performance IQ (PIQ), Verbal Comprehension Index (VCI), Perceptual Organization Index (POI), and Processing Speed Index (PSI) scores improved significantly across time, whereas no significant change occurred on the Working Memory Index. Specifically, test scores increased approximately 3, 11, 6, 4, 8, and 7 points, respectively on the VIQ, PIQ, FSIQ, VCI, POI, and PSI for both groups. Notably, the degree of improvement was similar regardless of whether the inter-test interval was 3 or 6 months. These findings suggest that prior exposure to the WAIS-III yields considerable increases in test scores. Reliable change indices indicated that large confidence intervals might be expected. As such, users of the WAIS-III should interpret reevaluations across these intervals cautiously.

Global-local visual processing in posttraumatic stress disorder.

The purpose of this study was to examine a behavioral index of hemispheric asymmetry (i.e., visual hierarchical attention) in posttraumatic stress disorder (PTSD), a disorder characterized by anxiety and other emotional symptoms. A reaction time based, computerized, global-local visual paradigm was administered to 26 PTSD-diagnosed and 22 psychopathology-free right-handed, male Vietnam War zone veterans. Results indicated that PTSD-diagnosed veterans displayed slower reaction times to all targets than the no-mental disorders comparison sample. However, findings also revealed a Group x Target location interaction in which the PTSD group was slower than the no-disorders comparison sample to respond to local, but not global, targets. Moreover, relative global bias was greater among PTSD-diagnosed veterans than their no-diagnosis counterparts. Findings provide partial support for the hypothesis that PTSD may be associated with a functional cerebral asymmetry favoring the right hemisphere.

Normative data for the symbol cancellation test in young healthy adults.

Mesulam's (1985) symbol cancellation test (SCT) provides a measure of neglect, organizational process, and attention. Although the SCT lends itself to qualitative interpretation, normative data would be helpful for interpreting errors and time to complete this test. SCT normative data are provided for healthy young adults and the contribution of age, education, ethnicity, and gender to SCT performance is examined. Results were as follows: Age was significant (p < .05) and education approached significance (p = .06) as predictors of SCT performance, but percentile ranks revealed an unstable performance pattern across age and education. Thus, normative data for the SCT are provided for the entire sample (n = 136). Conclusions are as follows: Healthy young adults make few errors and complete the SCT in under 2 min, consistent with general findings (Mesulam, 1985). In addition, a relation likely exists between SCT performance and age and education, but a larger sample seems warranted to reliably model the pattern.

Relationship between clock-drawing and neuropsychological and functional status in elderly institutionalized patients with schizophrenia.

OBJECTIVE: The authors sought to examine the usefulness of the clock-drawing test (CDT) as a measure of general cognitive and adaptive functioning in elderly patients with schizophrenia. METHODS: CDT performance of elderly institutionalized patients with schizophrenia were contrasted with a comparison group, similar in age. Cognitive and functional status was examined using an expanded battery from the Consortium to Establish a Registry for Alzheimer's disease and the Psychogeriatric Dependency Rating Scale. RESULTS: Patients (N=21) performed more poorly overall on the CDT than the comparison group (N=21), with greater clock number and hand errors. Production of the clock's gestalt did not differ between groups. In patients, overall CDT performance and clock hand placement were significantly correlated with general cognitive functioning, memory, visuoconstruction, and word-list generation. CDT global and hand placement performances corresponded to patients' general orientation. CONCLUSIONS: Impaired CDT performance in elderly patients with schizophrenia is not attributable to normal aging. Also, the CDT uniquely relates to an array of cognitive abilities in this population, validating its multicognitive character and implicating multiple brain regions. The CDT's tolerability and brevity make it attractive for use in geriatric schizophrenia.