Early expression of smooth-pursuit eye movement abnormalities in children of schizophrenic parents

Psychosis in children: diagnosis and treatment

The diagnosis of childhood psychosis raises a host of unresolved problems, despite the Diagnostic and Statistical Manual Of Mental Disorders, 4th edition, Text Revision (DSM-IV-TR) giving identical symptoms and definitions for children, adolescents, and adults. The fantasy lives of children, and issues of developing language and cognition (including retardation), all impair diagnostic accuracy, particularly when differentiating between childhood-onset schizophrenia (COS) (≤12 years), bipolar affective disorder, major depressive disorder, and even obsessive-compulsive disorder and attention-deficit/hyperactivity disorder: the catch-all classification, psychosis not otherwise specified (PNOS), is always available for conundra that prove unsolvable. Typical if nonpathognomonic features include neurocognitive difficulties. Multiple screening instruments and specialized versions of semistructured diagnostic interviews are available. Although smooth-pursuit eye-tracking movements may prove a genetic marker for COS, etiologies are likely to be oligogenetic rather than related to a single gene. No specific biological markers or neuroimages have been identified. As such, psychoses may be indicative of a more general pattern of brain dysfunction. Drug treatments are largely based on the adult literature because of a dearth of controlled data below age 18. There are still no rigorous studies of psychosocial treatments and psychotherapy specific to childhood psychosis.

Vertical and horizontal smooth pursuit eye movements in children: a neuro-developmental study

An evaluation of eye movements is very useful in neurological disorders but is complicated by issues such as maturation and lack of normative data in children. In order to address these issues we studied smooth pursuit eye movements of 65 normal children aged 7-11 years old. The gain of horizontal smooth pursuit (HSP) was higher than the gain of the vertical smooth pursuit (SP) and this difference had a statistical tendency to disappear with aging from 7 to 11 years. These data suggest that, in the cerebral regions involved in the control of SP, i.e. posterior parietal and superior temporal lobe regions, the networks for VSP mature latter than those for HSP.

Is motion perception deficit in schizophrenia a consequence of eye-tracking abnormality?

BACKGROUND

Studies have shown that schizophrenia patients have motion perception deficit, which was thought to cause eye-tracking abnormality in schizophrenia. However, eye movement closely interacts with motion perception. The known eye-tracking difficulties in schizophrenia patients may interact with their motion perception.

METHODS

Two speed discrimination experiments were conducted in a within-subject design. In experiment 1, the stimulus duration was 150 msec to minimize the chance of eye-tracking occurrence. In experiment 2, the duration was increased to 300 msec, increasing the possibility of eye movement intrusion. Regular eye-tracking performance was evaluated in a third experiment.

RESULTS

At 150 msec, speed discrimination thresholds did not differ between schizophrenia patients (n = 38) and control subjects (n = 33). At 300 msec, patients had significantly higher thresholds than control subjects (p = .03). Furthermore, frequencies of eye tracking during the 300 msec stimulus were significantly correlated with speed discrimination in control subjects (p = .01) but not in patients, suggesting that eye-tracking initiation may benefit control subjects but not patients. The frequency of eye tracking during speed discrimination was not significantly related to regular eye-tracking performance.

CONCLUSIONS

Speed discrimination, per se, is not impaired in schizophrenia patients. The observed abnormality appears to be a consequence of impairment in generating or integrating the feedback information from eye movements. This study introduces a novel approach to motion perception studies and highlights the importance of concurrently measuring eye movements to understand interactions between these two systems; the results argue for a conceptual revision regarding motion perception abnormality in schizophrenia.

A review on eye movement studies in childhood and adolescent psychiatry

The neural substrates of eye movement measures are largely known. Therefore, measurement of eye movements in psychiatric disorders may provide insight into the underlying neuropathology of these disorders. Visually guided saccades, antisaccades, memory guided saccades, and smooth pursuit eye movements will be reviewed in various childhood psychiatric disorders. The four aims of this review are (1) to give a thorough overview of eye movement studies in a wide array of psychiatric disorders occurring during childhood and adolescence (attention-deficit/hyperactivity disorder, oppositional deviant disorder and conduct disorder, autism spectrum disorders, reading disorder, childhood-onset schizophrenia, Tourette's syndrome, obsessive compulsive disorder, and anxiety and depression), (2) to discuss the specificity and overlap of eye movement findings across disorders and paradigms, (3) to discuss the developmental aspects of eye movement abnormalities in childhood and adolescence psychiatric disorders, and (4) to present suggestions for future research. In order to make this review of interest to a broad audience, attention will be given to the clinical manifestation of the disorders and the theoretical background of the eye movement paradigms.

ADHD and schizophrenia phenomenology: visual scanpaths to emotional faces as a potential psychophysiological marker?

Commonalities in the clinical phenomenology and psychopharmacology of ADHD and schizophrenia are reviewed. The potential of psychostimulants to produce psychotic symptoms emphasizes the need for objective psychophysiological distinctions between these disorders. Impaired emotion perception in both disorders is discussed. It is proposed that visual scanpaths to facial expressions of emotion might prove a potentially useful psychophysiological distinction between ADHD and schizophrenia. There is consistent evidence that both facial affect recognition and scanpaths to facial expressions are impaired in schizophrenia, with emerging empirical evidence showing that facial affect recognition is impaired in ADHD also. Brain imaging studies show reduced activity in the medial prefrontal and limbic (amygdala) brain regions required to process emotional faces in schizophrenia, but suggest more localized loss of activity in these regions in ADHD. As amygdala activity in particular has been linked to effective visual scanning of face stimuli, it is postulated that condition-specific breakdowns in these brain regions that subserve emotional behavior might manifest as distinct scanpath aberrations to facial expressions of emotion in schizophrenia and ADHD.

Premorbid childhood ocular alignment abnormalities and adult schizophrenia-spectrum disorder

This study examined the relation between childhood ocular alignment deficits and adult psychiatric outcomes among children at high-risk for schizophrenia and controls. A sample of 265 Danish children was administered a standardized eye exam assessing strabismus and related ocular alignment deficits. All children whose mothers or fathers had a psychiatric diagnosis of schizophrenia comprised the first group (N=90). Children who had at least one parent with a diagnosis other than schizophrenia comprised the first matched control group (N=93). The second control group consisted of children with no parental diagnoses (N=82). In 1992, adult psychiatric outcome data were obtained for 242 of the original subjects. It was found that children who later developed a schizophrenia-spectrum disorder had significantly higher eye exam scale and strabismus scale scores compared to children who developed other non-psychotic psychopathology and children who did not develop a mental illness. The mean rank for children in the high-risk group (offspring of parents with schizophrenia) on the eye scale and the strabismus scale was greater than the mean rank for children in the matched control groups (both offspring of parents with other non-psychotic disorder and no mental illness), although the results failed to reach statistical significance. Results from this study suggest a premorbid relation between ocular deficits and schizophrenia-spectrum disorders in childhood prior to onset of psychopathology in adulthood. Strabismus may serve as a premorbid marker for spectrum disorders and may have implications for the understanding of early aberrant neurological development related to later schizophrenia-spectrum disorders.

Oculomotricity in childhood: is the normal range the same as in adults?

The study of oculomotricity is done by the evaluation of three systems: saccade eye movements (MOS), optokinetic nystagmus (NO) and smooth pursuit eye movement (MORL). The joint action of these three systems allows the visual field's establishment in different movement situations.

AIM

To compare the value of oculomotricity in normal adults and children to confirm, or not if it is viable to use the same parameters of adults normality to children's exams interpretation.

STUDY DESIGN

Clinical with transversal cohort.

MATERIAL AND METHOD

We studied MOS, NO and MORL in 50 normal children and in 35 adults and the results were compared by the t Student test.

RESULTS

The data analysis showed significant difference between children and adults (significance at level +/- = 0.05)

DISCUSSION

In the literature we have found evidence that myelinization of the vestibular pathways happen at about 16 weeks and the pyramidal tracts, at 24 months. Oculomotricity is finished at this time. Other papers describe the importance of these tests in the diagnostic of neurological diseases, visual alterations and as predictors of the risk of schizophrenia development but they do not report the normal range in children. In our study we found increased latency of MOS, increase in gain of NO, reduction in gain and increase in the distortion of MORL in children if compared to adults, which is in accordance with the literature. These alterations can be explained by the low attention during the tests and the immaturity of ocular movements' control in children.

CONCLUSION

Therefore, the establishment of a parameter of normality to the oculomotricity in childhood is necessary for the correct analysis of the oculography to avoid misinterpretation of the exam.

Childhood-onset schizophrenia: smooth pursuit eye-tracking dysfunction in family members

BACKGROUND

Childhood-onset schizophrenia (COS), a severe form of the disorder, is of interest for etiologic studies. Smooth pursuit eye-tracking dysfunction (ETD) is a biological marker for schizophrenia.

AIMS

To compare familial eye-tracking abnormalities for COS and adult-onset schizophrenia (AOS).

METHOD

Eye-tracking performance for 70 COS parents, 64 AOS parents and 20 COS siblings was compared to their respective age-matched control groups.

RESULTS

COS and AOS parents had higher rate of dichotomously rated eye-tracking dysfunction than their respective controls (16% vs. 1% and 22% vs. 4%, respectively). COS parents and siblings also differed from controls on several continuous measures. However, scores for COS, AOS and control groups overlapped extensively.

CONCLUSIONS

Genetic factors underlying eye-tracking dysfunction appear more salient for COS. However, eye-tracking measures have to be used with caution for endophenotypic definition due to low predictive power.

DECLARATION OF INTEREST

The study was done at the National Institutes of Health.

Neurobehavioral deficits in offspring of schizophrenic parents: liability indicators and predictors of illness

High-risk research in schizophrenia incorporates several different strategies for studying individuals who are defined by different criteria as being at risk for future development of schizophrenia. Variables from a wide range of domains have been included in these studies. Several reviews of high-risk research have attempted to cover the field broadly, whereas others have been more sharply focused on research subjects defined by specific criteria or on particular classes of variables. Among the review articles and collections of project reports on high-risk research in the past two decades are: Watt et al. [1984: Children at risk for schizophrenia: a longitudinal perspective]; Nuechterlein and Dawson [1984: Schizophr Bull 10:160-203]; Nuechterlein [1986: J Child Psychol Psychiatr 27:133-144]; Erlenmeyer-Kimling and Cornblatt [1987: J Psychiatr Res 26:405-426]; Goldstein and Tuma [1987: Schizophr Bull 13:369-371]; Asarnow [1988: Schizophr Bull 14:613-631]; Moldin and Erlenmeyer-Kimling [1994: Schizophr Bull 20:25-29]; Mirsky [1995: Schizophr Bull 21:179-182]; Gooding and Iacono [1995: Manual of developmental psychopathology] McNeil [1995: Epidemiol Rev 17:107-112] Olin and Mednick [1996: Schizophr Bull 22:223-240]; Cornblatt and Obuchowski [1997: Intl Rev Psychiatry 9:437-447]. This paper presents an overview of findings from recent (the past decade and a half) prospective studies of children of schizophrenic parents, with a focus on neurobehavioral (neurocognitive, neuromotor, and neurophysiological) variables that may reflect aspects of the genetic liability to schizophrenia and related disorders. The few neuroimaging studies on children of schizophrenic parents are also briefly mentioned. Because of space limitations, the overview is not intended as a comprehensive or detailed review of this area of high-risk research.

Early expression of a pathophysiological feature of schizophrenia: saccadic intrusions into smooth-pursuit eye movements in school-age children vulnerable to schizophrenia

OBJECTIVE

Neurodevelopmental hypotheses of schizophrenia propose that the responsible pathology occurs much earlier than the usual onset of illness in late adolescence. Nonspecific neurocognitive and behavioral deficits found in children vulnerable to schizophrenia support this hypothesis. This report describes early deficits in a putative genetic endophenotype, saccadic intrusions into smooth-pursuit eye movements (SPEM).

METHOD

SPEM were recorded in 189 children aged 6-15 years: 49 children with schizophrenia, 60 nonpsychotic first-degree relatives, and 80 typically developing children.

RESULTS

Children with schizophrenia demonstrated poorer gain and a significantly increased frequency of leading saccades and large anticipatory saccades; however, only leading saccades differentiated first-degree relatives from typical children. Admixture analysis indicates that 94% of children with schizophrenia, 50% of first-degree relatives, and 19% of typically developing children have abnormally increased frequencies of leading saccades.

CONCLUSIONS

Typically developing young school-age children have a leading saccade phenotype similar to that of adults, suggesting this brain function is fully developed by early school-age years. The abnormal leading saccade phenotype, a schizophrenia-associated familial brain dysfunction, is present by 6 years of age, more than a decade before the highest risk for onset of psychosis. Treatment and prevention strategies will need to consider the early neurodevelopmental nature of schizophrenia.

Differential effects of cigarette smoking on performance of a smooth pursuit and a saccadic eye movement task in schizophrenia

Schizophrenic patients demonstrate a number of physiological defects including smooth pursuit eye movement dysfunction (SPEM), involuntary reflexive saccades to a prepotent stimulus during saccadic tasks, and increased response to the second of two identical auditory stimuli, the P50 evoked potential response. The P50 deficit appears to be mediated by the alpha7 nicotinic cholinergic receptor. This study compared the failure of saccadic inhibition demonstrated in two different eye movement tasks, to see if either deficit, like the P50 inhibitory deficit, was normalized by nicotine. Fifteen smoking schizophrenic patients and 15 smoking non-schizophrenic subjects were compared on the percentage of premature saccades in a memory-guided saccadic task, and the frequency of intrusive small and large anticipatory saccades during a SPEM task. No significant effects or interactions of smoking, group or time on premature or large anticipatory saccades were detected. However, leading saccades demonstrated a significant group x time x smoking interaction. Leading saccades may therefore be a measure of cholinergic inactivity and thus part of the alpha7 nicotinic receptor dysfunction observed in schizophrenia. However, premature saccades and large anticipatory saccades, although measures of inhibitory dysfunction in schizophrenia, appear to be unrelated to the nicotinic system.

Eye movement abnormality suggestive of a spatial working memory deficit is present in parents of autistic probands

Autistic probands exhibit impaired spatial accuracy and impaired response suppression errors during a delayed oculomotor response task. Family members of autistic probands, and thus the possible familial nature of these deficits, have not been assessed. Eleven parents of autistic probands and 17 adults from unaffected families, ages 25-50 years, completed oculomotor delayed-response tasks. Parents of autistic probands demonstrated poorer spatial accuracy than the comparison group (p = .002), with no significant differences between groups on percentage of premature saccades or latency of remembered saccades. Spatial working memory deficits, as measured by the delayed oculomotor response task, appear to be familial in families with an autistic proband. These deficits deserve further evaluation as a potential endophenotypic marker for genetic risk for autism.

Visual processing and neuropsychological function in schizophrenia and schizoaffective disorder

Persons with schizophrenia and schizoaffective disorder exhibit deficits in both visual processing and neuropsychological tasks. Little is known, however, about whether these deficits are related to one another. We administered psychophysical tests of visual discrimination and recognition, and neuropsychological tests of abstract flexibility, verbal learning, visual memory, working memory and attention to 42 outpatients with stable but chronic schizophrenia or schizoaffective disorder. Multiple regression analyses were performed to determine the relationship between these measures of neuropsychological function and visual psychophysical performance. Results indicated that motion perception was associated with working memory, and that the addition of a memory component to motion perception (motion recognition) was associated with both working memory and visual memory. Visual performance was not associated with symptom severity as measured by the PANSS. These results suggest that psychophysical tests of visual processing may contribute to deficits on neuropsychological tests of visual cognition, and may also reflect cross-modal disturbances of working memory function.

Parsing cognition in schizophrenia using saccadic eye movements: a selective overview

Eye movements provide a behavioural measure of sensorimotor processing and higher cognitive functions of the brain. With the development of novel paradigms that can be used for the study of various cognitive operations, saccadic eye movements in particular, have become increasingly popular. Patients with schizophrenia have neurocognitive impairments that can be readily investigated with these paradigms. From animal, human lesion and neuroimaging studies, the cerebral centres underlying saccadic eye movements have been identified. The areas of the prefrontal cortex include the dorsolateral prefrontal cortex, the frontal eye fields, the supplementary eye fields, and the anterior cingulate cortex. Pathology of saccadic eye movements, therefore, provides information on the functional status of the underlying neural circuitry in brain disorders such as schizophrenia. In this paper, we evaluate: (i) methodological considerations that are central to the design and application of saccadic paradigms; (ii) brain activation that is associated with saccadic paradigms; (iii) recent findings in healthy subjects and schizophrenic patients; (iv) saccadic abnormalities in other psychiatric and neurological disorders and in individuals at risk for developing schizophrenia.

Eye movement dysfunction as a biological marker of risk for schizophrenia

OBJECTIVE

Our aim was to review smooth pursuit eye movement (SPEM) studies in schizophrenia and groups at high risk for schizophrenia, with a view to evaluating the utility of SPEM dysfunction as a biological marker of risk for schizophrenia.

METHOD

Smooth pursuit eye movement studies, related saccade function and the unresolved issues in this area of schizophrenia research were addressed. The different perspectives on the trait marker status of SPEM dysfunction, provided by both high-risk studies and related developmental research were considered. Attention was also given to the relationship between eye movement dysfunction and symptom profiles.

RESULTS

Converging evidence points to the robust and specific nature of SPEM dysfunction in schizophrenia, and highlights the role of frontal lobe and a related network dysfunction. The vast majority of 'high risk' studies support the view that SPEM dysfunction is also genetically specific to schizophrenia, and is not simply due to the overt expression of this illness. Studies assessing SPEM in relation to symptomatology show an association with the Disorganisation syndrome in particular.

CONCLUSIONS

Evidence for the specificity of SPEM dysfunction to diagnosed schizophrenia, as well as to healthy individuals with a genetic vulnerability to schizophrenia, suggests that the SPEM task has efficacy as a test of gene carrier status in schizophrenia, and therefore as a trait marker of risk for schizophrenia. Future studies should seek to explore the relationships between SPEM and other eye movement dysfunctions (antisaccades, express saccades), in view of evidence that some of these dysfunctions also show specificity for schizophrenia.

Smooth pursuit eye movements in schizophrenia and attentional dysfunction: adults with schizophrenia, ADHD, and a normal comparison group

BACKGROUND

Smooth pursuit eye movement (SPEM) abnormalities are found in schizophrenia. These deficits often are explained in the context of the attentional and inhibitory deficits central to schizophrenia psychopathology. It remains unclear, however, whether these attention-associated eye movement abnormalities are specific to schizophrenia or are a nonspecific expression of attentional deficits found in many psychiatric disorders. Adult attention-deficit/hyperactivity disorder (ADHD) is an alternative disorder with chronic attentional and inhibitory dysfunction. Thus, a comparison of SPEM in adult schizophrenia and adult ADHD will help assess the specificity question.

METHODS

SPEM is recorded during a 16.7 degrees per second constant velocity task in 17 adults with ADHD, 49 adults with schizophrenia, and 37 normal adults; all groups included individuals between ages 25-50 years.

RESULTS

Smooth pursuit gain and the frequency of anticipatory and leading saccades are worse in schizophrenic subjects, with normal and ADHD subjects showing no differences on these variables.

CONCLUSIONS

Many attention-associated SPEM abnormalities are not present in most subjects with ADHD, supporting the specificity of these findings to the attentional deficits seen in schizophrenia.

Familial transmission of risk factors in the first-degree relatives of schizophrenic people

Schizophrenia is a complex illness with multiple pathophysiologic factors that contribute to its psychopathology. One strategy to identify these factors is to observe them in isolation from each other, by characterizing their expression in the relatives of schizophrenic probands. By Mendel's second law, each genetic factor should be independently distributed in a sibship, so that each can be observed by itself, uncomplicated by the general problems of the illness. Such independently distributed phenotypes are obviously useful for genetic analyses; however, they can also be considered together, to model how various brain dysfunctions may combine to produce psychoses. In addition to a sensory gating deficit linked to the alpha 7-nicotinic acetylcholine receptor locus, schizophrenics and their families have a number of other deficits, including decreased hippocampal volume on magnetic resonance images and increased plasma levels of the dopamine metabolite homovanillic acid. Although such research is far from complete, a heuristic model combining a sensory gating deficit, decreased hippocampal neuron capacity, and increased dopaminergic neurotransmission is consonant with current understanding of the neuropsychology of schizophrenia.

Neurobiological abnormalities in the relatives of schizophrenics

The inheritance of a complex illness such as schizophrenia likely involves the segregation of genetic factors, in combination with non-genetic or environmental abnormalities. This paper reviews several family studies of biological and clinical aspects of schizophrenia, that have attempted to observe such segregation in relationship to family history of schizophrenia to identify which factors appear to be related to the transmission of genetic risk.

The effects of age on a smooth pursuit tracking task in adults with schizophrenia and normal subjects

BACKGROUND

Performance during a smooth pursuit eye movement (SPEM) task has been proposed as a marker of genetic risk for schizophrenia, although the precise component of SPEM tracking most associated with genetic risk remains undetermined. Normal adult aging is associated with deterioration on SPEM tasks; it remains unclear whether investigations of SPEM abnormalities will allow inclusion of older subjects in genetic studies. This study examines 1) the effect of normal aging on several components of SPEM performance; and 2) whether schizophrenic-normal differences found in young adults continue over a broad adult age span.

METHODS

SPEM was recorded during a 16.7 degrees per sec constant velocity task in 64 normal adults, ages 18 to 79 years, and 58 schizophrenic subjects, ages 18 to 70 years.

RESULTS

Smooth pursuit gain, the percent of total eye movements due to catch-up saccades, the frequency of large anticipatory saccades, and the frequency of leading saccades all deteriorate with increasing age. After correction for age, schizophrenic to control differences persist on most eye movement variables with the largest effect sizes for leading saccades (1.56) and smooth pursuit gain (1.17).

CONCLUSIONS

The tendency to use saccades to anticipate target motion, even in small steps (leading saccades), deserves further attention as a potential marker useful in genetic analyses.

Smooth pursuit performance in families with multiple occurrence of schizophrenia and nonpsychotic families

BACKGROUND

Eye tracking dysfunction (ETD) has been put forward as a trait marker for biological susceptibility to schizophrenia with the hope of identifying a link to specific cerebral lesions.

METHODS

Eye movements were recorded using infrared oculography in 8 families (67 members) showing multiple occurrence of schizophrenia and in 9 nonpsychotic families (80 members). Triangle wave stimuli at 15 degrees/s and 30 degrees/s were used and gains (eye velocity/target velocity), rates and amplitudes of different saccade categories (catch-up, back-up, anticipatory saccades, and squarewave-jerks) were determined.

RESULTS

In the relatives, the same deficit in maintenance of smooth pursuit performance was found as was seen in the schizophrenic patients. This deficit, which was not observed in the nonpsychotic families, consisted of lower gains for leftward as compared to rightward pursuit. This was emphasized most clearly at 30 degrees/s and was associated with an excess of catch-up saccades in the schizophrenic patients, whereas in the relatives a tendency to exhibit more and larger anticipatory saccades was observed.

CONCLUSIONS

The results confirm the hypothesis that eye-tracking dysfunction is a phenotypic marker for genetic liability to schizophrenia. Neurophysiologically, a cerebral dysfunction which includes one or more of the oculomotor centers can be assumed in subjects who carry a genetic susceptibility to schizophrenia.

Deficient cancellation of the vestibular ocular reflex in schizophrenia

Schizophrenia has long been associated with difficulties in visual tracking of a moving object. Deficits are most notable in tracking tasks that require inhibition of saccades during active smooth pursuit. In order to assess whether there is a more global problem in inhibition of other eye movement systems while the smooth pursuit system is active, this study examined cancellation of the vestibular ocular reflex (VOR). Cancellation of the VOR occurs in a task in which the subject is rotated while looking at a target that is also being rotated. This requires the subject to use the pursuit system to override the VOR, maintain the eye at a stable location within the orbit, and thus retain visual gaze upon the target. Thirteen individuals with schizophrenia and 15 normals were assessed during clockwise rotation at 60 degrees s-1. Schizophrenic subjects had a significant increase in counterclockwise slow velocity eye movements, suggesting an impaired ability to cancel the VOR. Cancellation of the VOR is thus another example of a breakthrough of an alternative eye movement system while the smooth pursuit system is active. Because of the simplicity of the VOR and its suitability for animal modeling, investigation of this phenomenon may delineate more precisely the mechanisms of visual tracking dysfunction in schizophrenia.

Anticipatory saccades during smooth pursuit eye movements and familial transmission of schizophrenia

BACKGROUND

Smooth pursuit eye movement (SPEM) abnormalities are a putative marker of genetic risk for schizophrenia. Accurate SPEM performance requires the subject to activate neural systems responsible for smooth pursuit tracking, while simultaneously suppressing activity of neurons responsible for saccadic movements that would move the eye ahead of the target. This study examined whether specific aspects of SPEM dysfunction cosegregate with genetic risk in parents of schizophrenic probands.

METHODS

Eighteen probands and their parents had SPEM recorded. Parents with an ancestral history of schizophrenia were hypothesized to be more likely than their spouses without such a history to carry a genetic risk for schizophrenia.

RESULTS

Ten families had a single parent with a positive ancestral history for schizophrenia. The frequency of anticipatory saccades, which were mostly small, and the fraction of total eye movement that they represented were the only measures that differentiated the more likely genetic carrier parents in these families from their spouses and age-matched normals.

CONCLUSIONS

Failure to suppress saccadic anticipation of target motion during smooth pursuit appears an aspect of SPEM dysfunction related to presumed genetic risk for schizophrenia.

Delusional disorder and eye tracking dysfunction: preliminary evidence of biological and clinical heterogeneity

This study used eye tracking movement tests to examine the relationships between frontal field functions and clinical features. Smooth pursuit and voluntary saccadic eye movements were recorded and analyzed in 34 delusional disorder (DD) patients and in 40 normal subjects. The DD group differed significantly from the group of normal subjects in some eye tracking performances. As reported in our previous study (Gambini et al., 1993), DD patients showed abnormalities of voluntary saccadic eye movements. In this study, we also found abnormal smooth pursuit eye movements, indicating a cerebral dysfunction similar to those detected in schizophrenic patients. Moreover, normal smooth pursuit eye movement performance in DD patients was related to remitted depressive mood and probably to benefit from antipsychotic medications, thus supporting the idea of the biological and clinical heterogeneity of DD.