Schizophrenic Vulnerability Research Articles

Schizophrenia and eye movement – a new diagnostic and therapeutic concept

In the present article, conclusions are drawn from four papers on the genesis of schizophrenia, published in Medical Hypotheses between 1999 and 2002, knowledge of which is required to understand this paper in greater depth. For these, the author had developed two sight tests in which schizophrenic patients revealed a stronger fusional reactivity of the nasal than of the temporal foveal halves and a disconnection between peripheral and foveal vision. Both phenomena could be explained by a reversed crossing of foveal projections in the chiasma opticum constituting a genetic vulnerability which, in case of additional defects of binocular balance, could result in a foveal convergence stimulus being executed as a divergence movement by one of the eyes. The author has now succeeded in finding a very simple standardized method to discover the described vergence abnormality, the Hook test, part of the ZEISS Near Pola Test, which would therefore be suitable for detecting schizophrenic vulnerability in screening tests so that the outbreak of schizophrenia could be prevented by an early correction of the additional visual defects. The movement impulses resulting from the erraneous vergence are analyzed and explain the phenomenon of the schizophrenic’s “mad look”. The connection between the somatic component and the patient’s psycho-social problems is shown and a detailed description given of non-neuroleptic methods of rectifying both.

Further evidence for a reversed crossing of foveal projections in schizophrenic vulnerability

Further evidence in support of the thesis developed in a previous article published in Medical Hypotheses (Sept. 2000) proposing that schizophrenic vulnerability might consist of the temporal instead of the nasal foveal projections crossing over in the chiasma opticum has been provided by an experiment in which pinholes are used to isolate foveally stimulated from peripherally stimulated vergence. By shifting the pinholes inwards or outwards a dilemma is created regarding the fusion of the edges of the two pinholes or of a single diode light seen at the inner or outer edges of the pinholes. It was revealed that schizophrenic patients never solved the dilemma in favour of what was represented on the temporal foveal halves while this was always the case in the control group. At best, the patients fusioned neither the diode light nor the pinhole edges but saw both double. An explanation is given as to how this disturbance might be based on the interchange of nasal and temporal foveal projections and might lead to the dissociation of the visual goals of the two eyes, as shown in a previous test. The cause of markers of schizophrenic vulnerability mentioned in literature, in particular saccaded SPEM, P50 response and hyperdopaminergia, is related to such an interchange and suggestions are made for further experiments. Finally, the difficulty of schizophrenic patients to distinguish between reality and illusion is attributed to a disconnection of spatial and object perception.

Psychopathology of Common Sense

It is well established by psychopathological research that disorders of self-experience are among the main features of schizophrenic prodromes in a pathogenetic sense. Disorders of the phenomenal self, as "lack of ipseity" (the vanishing of the feeling of being embedded in oneself and of distinctiveness between the self and the outer world) and "hyper-reflexivity" (the monitoring of one's own life entailing the tendency to objectify parts of one's own self in an outer space) are considered key phenomena of schizophrenic vulnerability. In this paper, I argue that the analyses of the disorders of phenomenal self catch only some dimensions of schizophrenic vulnerability, since they mainly focus on the pathological changes in subjective experience of an isolated self and disregard the fact that the self is not purely personal. Because our existence is fundamentally tied to a social existence, the feeling of one's own self and the sense of "reality" of an experience are products of intersubjectivity and not only a private process based on introspection or reflexivity in which one is engaged in an idiosyncratic way. Building on, and extending, contributions of the phenomenological tradition, I attempt to demonstrate that intuitive attunement is the basic prerequisite for establishing one's sense of "reality" (feeling familiarly related to one's environment) and for establishing one's sense of "ipseity" (the sense of existing as a subject of awareness). In the last part of the paper, I show the importance of the concepts "lack of attunement" and "antagonomia" (the rejection of conventional knowledge and intuitive attunement, experienced as dangerous sources of loss of individuality) to establish a comprehensive theory of schizophrenic vulnerability. I finally discuss the implications of this view for empirical research and clinical management of schizophrenic vulnerability.

Schizophrenic vulnerability: a deficiency of the correlation between foveal perception and oculomotor proprioception?

In a previous paper published in Medical Hypotheses, the author proved by a simple mirror test a dissociation between the goals of selective attention and bifoveal fixation in a schizophrenic patient. In the present article, she enters into the details of the patient’s results in ophthalmological tests which revealed an opposite deviation of accommodation and vergence, compensated in a way incompatible with Hering’s law. She expounds that Hering’s law is based on the correlation of retinal data with proprioceptive information of the exterior eye-muscles, and that schizophrenic vulnerability might consist of a disturbance of this correlation favouring fusion of patterns in the remote and external space over fusion in the near and central space. Some phenomena found in schizophrenic patients and their carrier parents are explained in the light of this hypothesis. Finally, the author gives detailed advice on how to overcome difficulties in the correction of the ophthalmological deviations that induce the vulnerability to take effect.

Visually-guided saccadic eye movements in adolescents at genetic risk for schizophrenia

Visually-guided saccades of 21 offspring of schizophrenic parents and 21 individually matched controls were compared with regard to the frequency of occurrence of saccadic hypometria and hypermetria, non-fixations, and omissions of target jumps. Target steps ranged from 10 to 60 °, and interstimulus intervals averaged 2.5 s; subjects were promised financial reward depending on performance. Recordings were carried out at the subjects' homes. To screen for cognitive abilities and psychopathological behavior, subjects were tested by means of an intelligence scale and a behavioral checklist. With large target steps (40–60 °), the high-risk group made significantly more grossly hypometric saccades (gain ≤0.8) than the control group; responses to small target steps (10–30 °) exhibited a similar, albeit statistically not significant, trend. There were no significant differences with regard to the occurrence of hypermetria. Non-fixations scored marginally higher in the high-risks as compared to controls, but this was again not a significant difference. The incidence of omissions of saccades was very low in both groups. The results of the study suggest that subjects at genetic risk for schizophrenia may differ from controls by an increased incidence of conspicuously hypometric saccades. Clearly, this difference is not caused by a deficit of the saccadic motor circuitry proper; comparison to control data obtained with a similar experimental protocol suggests that it probably reflects an impaired internal control of saccades in the presence of distraction and stress. The relevance of saccades as indicators of a possible schizophrenic vulnerability is discussed.

Multiple deficit theory of schizophrenia: incidence of markers vs. symptoms.

Forty schizophrenic, 20 affective-disordered, and 40 matched normal control subjects were compared on postulated marker and symptom measures of schizophrenic deficits in: (a) affect; (b) attention; (c) proprioception; and (d) thought. The schizophrenic group was significantly more impaired on all four vulnerability markers than were the other two groups, while the schizophrenic and affective-psychotic groups showed comparable impairments on three of the psychotic symptom deficits. The incidence of multiple marker deficits was significantly greater in the schizophrenic than in the affective group. The hypothesis of independence of marker deficits was supported by the absence of any significant correlations among markers in the schizophrenic sample. The data support the theory that independent markers of schizophrenic vulnerability may potentiate schizophrenic disorders when their incidence is concurrent and at deficit levels.

Eye movements in spectrum personality disorders: comparison of community subjects and relatives of schizophrenic patients

The purpose of the current study was to test the specificity of an association between eye tracking abnormality and schizophrenia spectrum personality symptoms in the family members of schizophrenic patients. The studies of biological markers for genetic vulnerability to schizophrenia, which test an association between a biological measure and schizophrenia spectrum personality symptoms, are constrained, since these personality symptoms may lack the specificity for a schizophrenic phenotype. An association between a behavioral measure and these personality symptoms in general can easily be false (i.e., not related to schizophrenic vulnerability). In contrast, a strong deviant finding in the relatives of schizophrenic patients with spectrum personality symptoms, in the presence of a relatively normal finding in spectrum subjects without a known history of schizophrenia, makes the biobehavioral measure an interesting candidate for such investigations. Seventy-five subjects recruited from the community who did not have a family history of psychosis completed the study (24 of the 75 had significant schizophrenia spectrum personality symptoms). Thirty-two first-degree relatives of schizophrenic patients (13 with spectrum symptoms) completed the study. Subjects were 18-45 years old and had no DSM-III-R axis I diagnosis. Qualitative smooth pursuit eye movement score was significantly worse in relatives with the spectrum symptoms than in spectrum subjects without a family history of schizophrenia and the nonspectrum relatives. Schizotypal and schizoid symptoms explained a significant amount of the variance in the eye tracking measure in the relatives (31% and 20%, respectively) but not in the community subjects (less than 2%). Relatives of schizophrenic patients with and without the spectrum symptoms had significantly longer antisaccade latency, in spite of comparable latency for visually guided saccades, than the community subjects. Smooth pursuit abnormality in subjects with schizophrenia spectrum personality disorders is specifically associated with a family history of schizophrenia.

Elements for understanding "schizophrenic vulnerability"

Studies of the negative symptoms of schizophrenia seem to be of interest. However, the description of these symptoms is problematic. Some cognitive tests seem able to establish data that can be used to help discriminate among schizophrenic syndromes and to understand their different pathophysiology. Some of the main tests are described. Remarks concerning their value and the conditions of their interpretations are made.

Disorders of eye movements in schizophrenia--a critical review and future perspectives

Disorders of smooth pursuit eye movements and saccadic eye movements have been reported frequently in schizophrenics. Probably 50% of the schizophrenic probands and of their unaffected relatives perform abnormal smooth pursuit movements. These deficiencies have been regarded as a possible genetic trait marker for schizophrenic vulnerability. Saccadic eye movements have been investigated less intesively. The most prominent pathological feature is a lack of precision of reflexive saccades in case of schizophrenic probands. Although a large body of research has been conducted, the multitude of the results of eye movement disorders in schizophrenics and also technical and methodological problems impair the significance of these findings. In this review, the most important results are critically elaborated and research perspectives are pointed out. A valid identification of eye movement abnormalities is necessary.

Torque Behavior in Schizophrenics, Elderly Persons, and Other Special Groups

The incidence of clockwise drawing (torque) was compared for 90 schizophrenics, 57 institutionalized elderly individuals, 24 general medical patients, 50 adults functioning well in the community, 71 graduate students, and 72 undergraduate college students. In view of Blau's (Blau, T. H. Torque and schizophrenic vulnerability: As the world turns. Am. Psychol., 32: 997-1005, 1977) previous finding that torque behavior in children is substantially associated with subsequent schizophrenic pathology an attempt was made to verify the pathological significance of torque. Results indicated that for all Ss combined 38 per cent produced torque. Only the elderly as compared with undergraduate students displayed a significant difference in incidence of clockwise circling, with the elderly producing more torque. The absence of any significant differences between adult schizophrenics and any of the other comparison groups raises serious doubts about the pathological importance of torque in adults. Moreover, since groups who would be expected to be neurologically more intact performed no different from those who would be expected to be less intact, the neural integrative defect explanation proposed by Blau would seem to be unwarranted.

Torque and schizophrenic vulnerability.

Torque and schizophrenic vulnerability.

Torque and schizophrenic vulnerability. As the world turns.

Torque and schizophrenic vulnerability. As the world turns.

The family patterns of 100 schizophrenic children observed at Bellevue, 1935-1952.

A follow-up study of 100 children first observed and diagnosed as childhood schizophrenics at the Bellevue Children's Service between 1935 and 1952 was conducted in which outcome was related to family pattern. The subjects' ages on first observation were 2 1/2–12 years and on follow-up in 1969 were 22–46 years. No pronounced variations in type of onset were found when the patients were grouped according to ethnic and religious derivation or socioeconomic status of their parents. Study of the children's family patterns showed that about three-fourths could be considered severely pathological, with psychotic, disturbed, or inadequate fathers or mothers or both. About one-third of the children adjusted more or less well to society as adults, the largest fraction from homes in which the mother functioned effectively, but all retained schizophrenic traits and vulnerability.