Relation of neuroleptic dose and tardive dyskinesia to attention, information-processing, and psychophysiology in medicated schizophrenics

The switch from conventional to atypical antipsychotic treatment should not be based exclusively on the presence of cognitive deficits. A pilot study in individuals with schizophrenia

BACKGROUND

Atypical antipsychotics provide better control of the negative and affective symptoms of schizophrenia when compared with conventional neuroleptics; nevertheless, their heightened ability to improve cognitive dysfunction remains a matter of debate. This study aimed to examine the changes in cognition associated with long-term antipsychotic treatment and to evaluate the effect of the type of antipsychotic (conventional versus novel antipsychotic drugs) on cognitive performance over time.

METHODS

In this naturalistic study, we used a comprehensive neuropsychological battery of tests to assess a sample of schizophrenia patients taking either conventional (n = 13) or novel antipsychotics (n = 26) at baseline and at two years after.

RESULTS

Continuous antipsychotic treatment regardless of class was associated with improvement on verbal fluency, executive functions, and visual and verbal memory. Patients taking atypical antipsychotics did not show greater cognitive enhancement over two years than patients taking conventional antipsychotics.

CONCLUSIONS

Although long-term antipsychotic treatment slightly improved cognitive function, the switch from conventional to atypical antipsychotic treatment should not be based exclusively on the presence of these cognitive deficits.

Pharmacological treatment effects on eye movement control

The increasing use of eye movement paradigms to assess the functional integrity of brain systems involved in sensorimotor and cognitive processing in clinical disorders requires greater attention to effects of pharmacological treatments on these systems. This is needed to better differentiate disease and medication effects in clinical samples, to learn about neurochemical systems relevant for identified disturbances, and to facilitate identification of oculomotor biomarkers of pharmacological effects. In this review, studies of pharmacologic treatment effects on eye movements in healthy individuals are summarized and the sensitivity of eye movements to a variety of pharmacological manipulations is established. Primary findings from these studies of healthy individuals involving mainly acute effects indicate that: (i) the most consistent finding across several classes of drugs, including benzodiazepines, first- and second- generation antipsychotics, anticholinergic agents, and anticonvulsant/mood stabilizing medications is a decrease in saccade and smooth pursuit velocity (or increase in saccades during pursuit); (ii) these oculomotor effects largely reflect the general sedating effects of these medications on central nervous system functioning and are often dose-dependent; (iii) in many cases changes in oculomotor functioning are more sensitive indicators of pharmacological effects than other measures; and (iv) other agents, including the antidepressant class of serotonergic reuptake inhibitors, direct serotonergic agonists, and stimulants including amphetamine and nicotine, do not appear to adversely impact oculomotor functions in healthy individuals and may well enhance aspects of saccade and pursuit performance. Pharmacological treatment effects on eye movements across several clinical disorders including schizophrenia, affective disorders, attention deficit hyperactivity disorder, Parkinson's disease, and Huntington's disease are also reviewed. While greater recognition and investigation into pharmacological treatment effects in these disorders is needed, both beneficial and adverse drug effects are identified. This raises the important caveat for oculomotor studies of neuropsychiatric disorders that performance differences from healthy individuals cannot be attributed to illness effects alone. In final sections of this review, studies are presented that illustrate the utility of eye movements for use as potential biomarkers in pharmacodynamic and pharmacogenetic studies. While more systematic studies are needed, we conclude that eye movement measurements hold significant promise as tools to investigate treatment effects on cognitive and sensorimotor processes in clinical populations and that their use may be helpful in speeding the drug development pathway for drugs targeting specific neural systems and in individualizing pharmacological treatments.

Relationship between neuroleptic dosage and subjective cognitive dysfunction in schizophrenic patients treated with either conventional or atypical neuroleptic medication

Previous research has suggested that high doses of conventional neuroleptics may induce neurocognitive deficits when assessed with standard tasks. However, little is known about the effects of high doses of neuroleptics (conventional or atypical) on subjective cognitive dysfunction. Recent research stresses the putative importance of self-reported cognitive deficits for both symptomatic outcome and medication compliance. The aim of the present study was to investigate the impact of neuroleptic medication on subjective cognition in patients treated with either conventional or atypical agents (clozapine, risperidone, olanzapine). Patients were asked to endorse the items of a questionnaire entitled 'Subjective Well-Being under Neuroleptic Treatment' prior to discharge. Subjective impairment, as assessed with the subscale 'mental functioning', was significantly correlated with greater conventional neuroleptic dosage after controlling for psychopathology (P<0.05). The difference between patients medicated with higher doses of conventional neuroleptics and those with lower doses was highly significant (P<0.001). In contrast, higher atypical neuroleptic doses were not associated with impairment.

The relationship between smooth pursuit eye movements and tardive dyskinesia in schizophrenia

OBJECTIVE

To examine the relationship between smooth pursuit eye movements and tardive dyskinesia (TD) in schizophrenia.

METHODS

Forty schizophrenic patients with TD and 25 non-TD patients had smooth pursuit eye movements tested with infrared oculography. In addition to the diagnosis of TD (present or absent), each patient had ratings of severity of TD.

RESULTS

There was no significant or strong association between TD and poor smooth pursuit eye movements.

CONCLUSION

The results stand in contrast to those of several previous studies, which were based on limited methodology. However, this study was not able to exclude definitively the possibility that TD is associated with poor smooth pursuit, perhaps with a small to moderate effect. Furthermore, these conclusions are limited to simple eye tracking protocols in which distractions are minimized. The question of whether or not TD is associated with poor smooth pursuit in schizophrenia needs to be resurrected.

The structure of schizophrenic symptoms: a meta-analytic confirmatory factor analysis

To quantitatively review all presently available evidence about the interrelations between positive and negative schizophrenic symptoms, we created an aggregate matrix of the intercorrelations among schizophrenic symptoms by combining data from 28 independent samples using meta-analytic procedures (net bivariate dfs ranging from 683 to 1657). Using confirmatory factor analyses, we then statistically compared four theoretically derived models of the structure of schizophrenic symptoms. Although a three-factor model (Liddle, 1987) best fit the data, results suggest that either more factors or different symptoms are required to account well for the latent structure underlying schizophrenic symptomatology. The nature of such augmented approaches, the opportunities and constraints inherent to multifactorial models, and the limitations of current instruments are discussed.

Memory impairment in schizophrenia: perspectives from psychopathology and pharmacotherapy

OBJECTIVE

To describe the concept of memory impairment in schizophrenia and the clinical implications of this concept in terms of patient assessment and neuroleptic drug use.

METHOD

Narrative literature review.

RESULTS

Individuals suffering from schizophrenia normally exhibit some degree of memory impairment. Recent work in psychopathology indicates that the impairment is comprehensive, involving the sensory, short-term, and long-term memory stores. Memory impairment appears to be a primary symptom of the disease, and its underlying causes are likely organic. A number of medications, however (for example, traditional neuroleptics and drugs that have pronounced anticholinergic activity), may cause or exacerbate impairment. In particular, anticholinergic agents used to treat extrapyramidal symptoms, a common complication of neuroleptic drugs, appear to have a deleterious effect on memory.

CONCLUSIONS

Memory impairment is an important consideration in the clinical assessment and management of patients with schizophrenia. The use of atypical antipsychotics like risperidone appears to have no impact on memory function; because risperidone is associated with a low incidence of extrapyramidal side effects, it can obviate the need for anticholinergic medications-thus offering greater hope of nondebilitative intervention. The advent of medications that are safer (on cognition) could also lead to generally better outcomes by facilitating compliance with drug regimens and rehabilitation programs.

Abnormal smooth pursuit eye movements in schizophrenic patients are associated with cerebral glucose metabolism in oculomotor regions

The purpose of this study was to test the hypothesis that abnormal smooth pursuit eye movements in schizophrenic patients would be related to cerebral glucose utilization in specific oculomotor regions. Eye movements were assessed with infrared oculography in 11 unmedicated schizophrenic patients and 13 normal comparison subjects. For the patients only, regional cerebral metabolic rate of glucose utilization was measured with positron emission tomography. Abnormal pursuit tracking in the patients was associated with relatively decreased metabolism in the frontal eye fields and increased metabolism in the caudate nuclei. The results are consistent with the hypothesis that these cerebral regions are involved in the pathophysiology of abnormal pursuit as related parts of a cortical-subcortical oculomotor circuit.

Type I and type II schizophrenia: relations between tonic electrodermal activity and clinical ratings before and after haloperidol treatment

To test the hypothesis that schizophrenic patients with positive vs. negative symptoms show different tonic electrodermal patterns, 26 patients with Type I schizophrenia and 19 patients with Type II schizophrenia were evaluated before and after 2 weeks of haloperidol treatment (standard daily dose = 4.5 mg). Clinical assessments were made with the Brief Psychiatric Rating Scale, the Scale for the Assessment of Positive Symptoms, and the Scale for the Assessment of Negative Symptoms. Skin conductance level (SCL) and spontaneous fluctuations (SF) frequency were recorded for each patient. Before treatment, Type I patients showed higher SCL and SF compared with Type II patients; after treatment, a significative decrease of clinical and psychophysiological variables was found only in Type I patients.

Dyskinesia in mentally handicapped women: relationship to level of handicap, age and neuroleptic exposure

The prevalence of dyskinesia in a randomly selected set of 61 mentally handicapped women with a range of diagnoses, levels of IQ and exposure to neuroleptics was assessed using the Abnormal Involuntary Movements Scale (AIMS). Overall, 64% of patients had dyskinesia on the AIMS. There was no correlation with neuroleptic exposure, although 43% of patients had been significantly exposed. There was no correlation between the presence of dyskinesia and the original handicapping diagnosis, and there was no increase in dyskinesia as the patients age increased. There was a significant increase in dyskinesia as IQ fell. This study backs the contention that there is a close association between cognitive impairment and movement disorder.

Effects of clozapine, fluphenazine, and placebo on reaction time measures of attention and sensory dominance in schizophrenia

Two reaction time (RT) paradigms were used to study clozapine's effects on sustained and selective attention compared to fluphenazine and placebo in 25 chronic schizophrenic patients. Sensory dominance was studied via simple and choice RTs to lights and tones, and on double-stimulus trials in which the two stimuli were presented simultaneously. Although 8 of the 25 patients could not perform the RT tasks when taking placebo, there were no effects of clozapine on simple or choice RT compared to placebo or fluphenazine. Subjects on all 3 treatments showed visual dominance: faster RT to lights than to tones on choice and double-stimulus trials. However, clozapine reduced this by means of a selective increase in RT to lights. Clozapine reduced failures to respond to the tone on double-stimulus trials. This was shown to be due to reductions in hallucinations. Clozapine does not generally improve attention, but it may increase the ability of schizophrenic persons to process nondominant or unattended stimuli possibly by increasing the efficiency of resource allocation. This may be partially mediated by a reduction in hallucinations.

A disturbance in the control of muscle force in neuroleptic-naive schizophrenic patients

The voluntary motor disturbances found among many schizophrenic patients consist of motor incoordination, disturbed pursuit tracking, difficulty following movement sequences, desynchronized tapping, and a myriad of neurologic soft signs. The problem with many of these observations is that it is extremely difficult to distinguish movement disorders related to neuroleptic treatment from those that may have occurred spontaneously. The aim of the present study was to examine potential disturbances in the voluntary control of steady-state force in neuroleptic-naive schizophrenic patients and normal comparison subjects. Twenty-one patients and 21 age- and gender-matched comparison subjects were studied. Spectral analyses of hand force instability revealed a significant difference between patients and comparison subjects. In 52 of the patients, the disturbance in the control of force exceeded the 95th percentile of the comparison mean. Degree of force instability was correlated with positive but not negative symptoms of schizophrenia. These findings suggest that schizophrenic patients may exhibit a disturbance in the control of muscle force that cannot be attributed to the neuroleptic effects of antipsychotic medication. The pattern of disruption, characterized by abnormal spectral energy within the 1.5 to 3.0 Hz range, suggests a motor disturbance that resembles tardive dyskinesia. Implicit within these findings of neuroleptic naive patients is the possibility that disturbances in the control of isometric force may represent spontaneous dyskinesia.

Disruption of saccade production during oculomotor tracking in schizophrenia and the use of its changes across target velocity as a discriminator of the disorder

A clear measure of eye movement disorder (EMD) that reliably separated schizophrenic individuals from others would both give insight into the brain control of the disorder and provide an aid in diagnosis. In the present study, a detailed analysis was carried out of the interactions between the pursuit and saccadic components of eye movements at different target velocities. The subjects comprised schizophrenic patients, unipolar depressed patients, and normal controls. The speed of the slow pursuit component did not differ among the groups, but schizophrenic subjects made more saccadic movements at low target velocities, though they started further away from the target at high target velocities. On the basis of these differences, a slope was computed of the linear function that related the number of saccadic eye movements to the velocity of a ramp visual target. Slope direction was negative for schizophrenic subjects but positive for unipolar depressive and normal subjects, and the correct classification rate for subjects was 84%.

Tardive dyskinesia: neuropsychological, computerized tomographic, and psychiatric symptom findings

Prior studies have suggested that schizophrenic patients with tardive dyskinesia (TD) have an unusual incidence of cognitive impairment, structural brain abnormalities, and negative symptoms. Twenty-seven schizophrenic patients with TD and an equal number of age-, gender-, and education-matched schizophrenic controls were studied. Each patient received neuropsychological testing, psychiatric symptom ratings, and most had cerebral computed tomography (CT) scans. Patients with TD significantly differed from controls on only 1 of 23, cognitive measures, and the overall group performance profiles were highly similar. No differences were observed on symptom ratings. Patients with TD had significantly smaller ventricular-brain ratios (VBRs) than controls. These data fail to support an association of TD with global measures of "organicity." Abnormal movements may result from specific dysfunction within the more purely motor circuits of the basal ganglia without compromising other neural systems involved in cognitive processing.

Genetic factors for the span of apprehension test: a study of normal twins

The Partial Report Span of Apprehension test has been found to detect cognitive deficits in some first degree relatives of schizophrenic patients. To assess the relative contribution of genetic vs. environmental factors on this measure, 19 monozygotic and 14 dizygotic female twin pairs, selected from a normal population, were tested on the Span of Apprehension test and an IQ test. Both Span of Apprehension test performance and IQ score had high heritabilities: 0.65 and 0.71, respectively. The mode of transmission for performance on the Span of Apprehension test appears to operate in a nonadditive manner. A multivariate behavioral-genetic model applied to the Span of Apprehension and IQ measures indicated that slightly less than half of the genetic effects important for the Span of Apprehension test are found in common with the genetic factors important for IQ. The phenotypic correlation between the Span of Apprehension and IQ measures can be attributed entirely to genetic factors. The influence of unique genetic components in the performance of the Span of Apprehension test in the general population heightens the promise of this measure as a genetic marker for schizophrenia.

Evaluation of the stability of neuropsychological functioning after acute episodes of schizophrenia: one-year followup study

Few studies have evaluated the longitudinal stability of neuropsychological deficits in schizophrenia. In the present study, 39 inpatients with DSM-III-R schizophrenia were administered a comprehensive battery of neuropsychological tests after achieving sufficient clinical recovery to warrant discharge, and again 1 year after the first assessment during a nonacute period. Significant improvement in neuropsychological functioning from the first to the second assessment was observed on several tasks, including the following: Trails A and B, Digit Symbol, Judgment of Line Orientation, recognition memory on the Rey Auditory Verbal Learning Test, the Wisconsin Card Sort, and Finger Tapping. These improvements were unrelated to treatment history, and were similar in first episode and chronic cases. For many patients, the improvement in functioning brought test performance into line with normative scores from test standardization samples. These results indicate that considerable improvement in neuropsychological functioning can occur in schizophrenic patients over the months following an acute episode of illness, and that recovery of cognitive functioning can occur after substantial clinical recovery from an acute episode of illness has already been achieved.

The effect of neuroleptics on cognitive and psychomotor function

There has been great variability and inconsistency in the reported effects of neuroleptic drugs on cognitive and psychomotor function in both patients and normal controls. Experimental design rather than any particular cognitive or psychomotor test appears to have determined the sensitivity of detection of neuroleptic drug effects. In general, sedative phenothiazines have been found to depress psychomotor function and sustained attention, but higher cognitive functions are relatively unaffected. In the majority of studies of schizophrenic patients, both cognitive function and attention improve with neuroleptic treatment, in parallel with clinical recovery. Negative symptoms are not increased and usually show slight improvement with neuroleptic treatment. Controls are more sensitive than schizophrenic patients to neuroleptic drug-induced impairments. Tolerance has been seen in patients but has not been demonstrated in normal volunteers. The way in which neuroleptics produce their beneficial effects in patients remains unknown. Three main hypotheses to replace early arousal theories are proposed: normalisation of attention, facilitated indirectly by suppression of 'released' limbic dopamine hyperactivity; normalisation of asymmetrical temporohippocampal function; or direct improvement of attentional processing. Studies of the effects of new antipsychotic drugs with selective actions and the development of more reliable and selective tests of psychomotor and cognitive functions are required.

Skin conductance responding in schizophrenic patients with abnormal involuntary movements

The present study tested the hypothesis that neuroleptic treatment modifies the skin conductance response (SCR) to loud tones. Schizophrenic patients with and without drug-induced abnormal involuntary movements were tested before and after drug withdrawal. During the on-drugs session, habituation of SCR correlated with the daily neuroleptic dose, and patients with tardive dyskinesia (TD) showed the fastest habituation of SCR. These findings were interpreted as indicating that SCR is attenuated by neuroleptics present during the examination and that TD patients demonstrate a preferential susceptibility to this effect. Withdrawal of medication resulted in slowing of SCR habituation only in TD patients, following which the entire sample showed a similar rate of habituation. These findings suggest that accelerated SCR habituation is not a stable trait of TD patients.

Association of tardive dyskinesia with increased frequency of eye movement disturbances in chronic schizophrenic patients. A clinical note

The study of eye movement dysfunction in chronic schizophrenics by electronystagmography revealed a significant increase of saccadic dysmetria as well as saccadic intrusions in smooth pursuit in schizophrenic patients with tardive dyskinesia (TD) compared with those without TD and with healthy controls. The pattern of eye movement dysfunction in schizophrenia allows clear discrimination from patients with similar movement disorders due to Huntington's disease. Of several possible explanation's of the schizophrenic eye movement dysfunction the authors favour the hypothesis of a common pathogenetic link between TD and eye movement disorders in schizophrenia, consisting in an underlying dysfunction of regions involved in the regulation of involuntary attention such as the parietal cortex and striatolimbic structures of the right hemisphere. Recent literature supports the assumption of right hemispheric dysfunction in schizophrenia.

Non-right-handedness and maleness correlate with tardive dyskinesia among patients taking neuroleptics

Forty-eight consecutive psychiatric outpatients receiving neuroleptics were assessed for handedness and the presence of tardive dyskinesia (TD). Twenty-seven patients had TD and 21 did not. Twenty-one of the patients with TD had some degree of non-right-handedness compared with 3 of the patients without TD. These results were found to be statistically significant. Maleness also correlated with the presence of TD, but the results were less robustly significant. These findings indicate that non-right-handedness and maleness may correlate with the risk of developing TD. To the author's knowledge, these findings have not been previously reported.

Effects of neuroleptics on electrodermal activity in schizophrenic patients: a review

The effects of neuroleptics on electrodermal activity (EDA) in schizophrenic patients are addressed in a review of research conducted since the publication of an earlier review by Tecce and Cole in 1972. It is concluded that neuroleptics reduce skin conductance level but that effects on other electrodermal parameters are less robust and may be confounded by methodological issues. A discussion of these issues is presented and directions for future research are proposed.

Tardive dyskinesia in schizophrenic patients: correlation with negative symptoms

The relationship between severity of tardive dyskinesia (TD) and the prominence of negative symptoms was assessed in 25 right-handed, medicated schizophrenic patients. TD was quantified using ultrasound detectors and frequency measurement techniques as well as with observer rating scales. Electromechanical studies revealed a systematic relationship between TD severity and negative symptoms; TD was more severe in patients with fewer negative symptoms. The correlation was small in magnitude.

Chronic neuroleptic effects on spatial reversal learning in monkeys

Cebus apella monkeys were chronically administered the antipsychotic drug fluphenazine decanoate for periods ranging from 3.5 to 5.5 years. In the present study, four of these monkeys and two controls were tested for cognitive abilities on a spatial learning task, which consisted of an original discrimination and four reversals of that discrimination. No effect of fluphenazine administration was seen in the rate of learning the original discrimination, but the carryover of learning across discrimination reversals was significantly reduced by fluphenazine. After overtraining on the original discrimination, the controls showed the normal difficulty in learning the first reversal. The fluphenazine-treated monkeys showed no such disruption. On subsequent reversals, the controls showed continually improving performance, so that on the third and fourth reversals they had near-perfect scores. On the other hand, the fluphenazine-treated monkeys showed no change over the four reversals. Unlike normal monkeys, their learning did not improve with practice. Although simple forms of learning seem to be relatively unaffected by chronic fluphenazine administration, more complex learning is disrupted.

Increased saccadic distractibility in tardive dyskinesia: functional evidence for subcortical GABA dysfunction

In mammals, GABAergic projections from the substantia nigra reticulata to the superior colliculus provide tonic inhibition to tectal neurons involved in the generation of saccades. Dysfunction of this pathway has been shown to produce saccadic "distractibility" in the experimental monkey. In two oculomotor paradigms, control of saccadic eye movements was tested in chronic schizophrenic patients with (n = 18) and without (n = 16) tardive dyskinesia (TD) and normal controls (n = 8). The three groups were matched by mean age; the TD and non-TD patient groups had similar duration of illness, benztropine and chlorpromazine equivalent doses and educational levels. A twofold increase in saccadic distractibility was observed in TD compared to non-TD schizophrenic patients, and both patient groups demonstrated a greater saccadic distractibility than normals. Furthermore, schizophrenic patients (both with and without TD) showed significantly increased latency for "volitional" saccades compared to the normal controls. These findings may provide further evidence for basal ganglia GABA dysfunction in tardive dyskinesia, as well as demonstrate oculomotor abnormalities in schizophrenic individuals.

Impaired performance in a saccadic tracking task in schizophrenic patients

The performance of schizophrenic patients in a task which requires a sequence of saccades guided by visuospatial cues is reported. A previous study recording eye movements determined a highly increased number of fixations necessary for this task in acute schizophrenic patients compared with normal controls. The performance of normal control subjects of different age groups and the correlation between the performance in the tracking task and the results of a clinical psychological test battery are described. Schizophrenic patients in a partly remitted state and in a remitted or mildly chronic state performed this task worse than matched control subjects; this was particularly indicated by the time score. The relation to the lifetime dosage of neuroleptic medication is considered.

Voluntary movement dysfunction in Huntington's disease and tardive dyskinesia

Psychiatric patients with tardive dyskinesia (TD) may be difficult to distinguish from those with Huntington's Disease (HD), who frequently have psychiatric symptoms. This study compared 14 patients with HD with 21 patients (15 schizophrenics and 6 with affective disorder), matched for involuntary movements, using a quantitated neurological examination and other objective and semi-objective tests. The HD group was significantly more impaired on measures of voluntary movement and saccadic eye movements. When the psychiatric group was subdivided, voluntary motor impairment was most marked in schizophrenics with both TD and parkinsonism. The implications of these findings are discussed.

Chronic haloperidol effects on oral movements and radial-arm maze performance in rats

Rats were examined for the development of adverse motor and cognitive effects during and after 24 weeks of chronic haloperidol (HAL) administration using an 8-arm maze and a computerized apparatus for measuring spontaneous oral movements. In the maze, HAL caused a significant decline in choice accuracy only during the first week of administration, whereas it caused a significant decline in locomotor speed throughout drug administration. There were no effects of HAL on maze behavior after withdrawal. Haloperidol reduced the number of mouth movements during drug administration, but after withdrawal there was a significant increase. This replicated a previous finding from our lab. The oral movements which did occur in the HAL-treated rats were slower than normal. The timing of the HAL-induced cognitive dysfunction was similar to the Parkinson-like disorder shown by patients given chronic neuroleptics, whereas the timing of the increase in oral movements after the withdrawal of HAL was more related to the appearance of tardive dyskinesia. There was evidence in both tests of a persisting sedation during chronic neuroleptic administration.