Cognitive function in manics with associated neurologic factors.

Researchers studying cognition in mania have assumed that mania is a homogeneous entity. Recent preliminary evidence indicates that some manic syndromes may be preceded by medical, pharmacological, and neurologic antecedents. While DSM-III suggests that mild cognitive impairment may be associated with these manic syndromes, studies to date have not documented this assertion. We compared bipolar patients with antecedent neurologic factors (neurologic manics, NM) to bipolar patients without such histories (primary manics, PM) on standard neuropsychological measures and clinical parameters to ascertain whether cognitive testing could be used as an adjunctive diagnostic tool in defining this subgroup of patients. Results indicated that the NM group was more dysfunctional in intellectual functioning and course of psychiatric illness than the PM group.

Relationships between stimulus intensity and amplitude of visual and auditory event related potentials.

Event related potentials were recorded from subjects presented with separate trains of lights and tones of three intensity levels (75, 240 and 750 fl and 60, 77 and 95 dB respectively). The auditory P1-N1 and N1-P2 components increased linearly with loudness, whereas in visual evoked responses, these components were maximal at an intermediate brightness. There was no correlation between responses to the two modalities. The results are examined in relation to current theories of cortical stimulus processing.

The late positive component of the evoked response in acute schizophrenics during a test of sustained attention.

To investigate the relationship between behavioral and cortical measures of impaired attention in schizophrenia, 17 hospitalized acute schizophrenics and 16 hospitalized nonpsychotic patients were studied. Event-related potentials (ERP) were obtained while subjects performed the Continuous Performance Test (CPT) under three conditions: First base line, Auditory-Visual Distraction, and Second base line. Schizophrenics made more errors of omission and commission and had longer reaction times. Analysis of the Late Positive Component (LPC) of the ERP revealed that both groups had an attenuated LPC during distraction and a larger LPC to the critical compared to the noncritical stimulus throughout all conditions. Schizophrenics had a smaller LPC and a smaller amplitude difference between the critical and noncritical stimulus than the nonpsychotics throughout all conditions.

The effect of distraction on acute schizophrenics' visual tracking.

To examine the nature of impaired smooth pursuit eye movement (SPEM) in schizophrenia, 16 hospitalized schizophrenics in the acute phase and 16 hospitalized nonpsychotic patients were studied. The experiment consisted of five 30-sec visual tracking phases: (i) base line (no distraction); (ii) auditory-visual distraction; (iii) middle base line; (iv) dichotic listening; and (v) final base line. Schizophrenics were characterized by significantly more velocity arrests throughout all phases of the experiment. Auditory-visual distraction did not impair either group's SPEM relative to base line performance. In contrast, dichotic listening significantly increased both groups' velocity arrests. This form of distraction also tended to produce greater impairment among schizophrenics. The failure of apparently intense auditory-visual distraction to significantly disrupt schizophrenics' SPEM suggests that inattentiveness alone does not account for schizophrenics' tracking impairment. This notion is supported by the finding that only the more intense distraction by dichotic listening produced a (trend toward) greater impairment in schizophrenics.