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Keywords:

  • exploratory eye movements;
  • gazing time scanning length;
  • recovery phase;
  • schizophrenia

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. REFERENCES

Abstract In the present paper exploratory eye movements were examined as biologic markers in both acute schizophrenic patients (acute patients discharged after approximately 3 months and treated as outpatients, n = 8; acute patients who were still in hospital after 6 months, n = 8) and chronic schizophrenic patients (hospital stay >5 years, n = 15) in comparison with age-matched healthy subjects (n = 30). Using an eye-mark recorder, exploratory eye movements were analyzed for mean gazing time (MGT), and total eye scanning length (TESL) as subjects viewed six simple pictures in preparation for copying them. In acute schizophrenic patients discharged after 6 months (DP), MGT became significantly shorter and TESL became longer after 3 or 6 months treatment. In acute schizophrenic patients during admission after 6 months, TESL became longer after 3 or 6 months of treatment. However, no significant changes were observed in chronic patients in these measures. In schizophrenic patients, negative symptom scores were positively correlated with MGT (r = 0.43; P < 0.001), and negatively correlated with TESL (r = −45; P < 0.001). These findings suggest that exploratory eye movements are a biologic state and trait marker useful for evaluation of schizophrenia.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. REFERENCES

Cortical event-related potentials (ERP) or eye movements have been studied as biologic markers in psychiatric disorders such as schizophrenia and mood disorder.1,2 In general agreement, ERP have been considered to be a trait marker and also a state marker that changes somewhat with treatment.3,4 Holzman et al. reported that schizophrenic patients have less globally accurate smooth pursuit and lower pursuit gain than that of normal control subjects.5,6

In studies of exploratory eye movements, subjects are examined with an eye-mark recorder as they view several pictures while the points of gaze are analyzed in several elements. This assessment method is considered to reflect abnormalities of eye movements and visual information processing in natural settings.2 Schizophrenic patients have been demonstrated to have a limited eye movement range and to maintain gaze in a given direction for a longer time than normal subjects.2,7 These findings are considered to be related to cognitive deficits, and the abnormal characteristics of eye movements might be trait markers for schizophrenia.

The important biologic markers of psychiatric disorders include two marker types. State markers appear and disappear together with clinical episodes, while trait markers are independent of variation in the clinical state. Eye movement dysfunction has been considered to be a trait marker for schizophrenia because the eye movement abnormality is neither normalized nor induced by neuroleptics, is independent of changes in the clinical state, and also does not occur in a schizophrenic patient's family members.7 The present study was performed to examine whether abnormal exploratory eye movements were a trait and/or a state marker for the three groups of the same schizophrenic patients for up to 6 months using an eye-mark recorder to trace eye movements as the subject viewed standardized simple pictures, as previously reported by Miyahira et al.8

METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. REFERENCES

Subjects

A group of 16 acute patients (mean age ± SD, 32.5 ± 11.2 years) and a group of 15 chronic patients (CP; 44.2 ± 7.6 years) with schizophrenia (all patients: 38.4 ± 11.3 years) diagnosed using Diagnostic and Statistical Manual of Mental Disorders (4th edn; DSM-IV) criteria9 by three psychiatrists were studied together with 30 age-matched healthy control subjects (age, 37.9 ± 13.6 years). Acute patients were further divided into two groups: one group included those patients who were discharged after approximately 3 months (96 ± 18 days), termed ’discharged patients’ (DP; n = 8). The other group included those patients who were still in hospital after 6 months (n = 8), termed ’admitted patients’ (AP). All subjects were right-handed and had normal vision. No control subjects had any history of neurologic disease, psychiatric disease, or substance abuse. All subjects gave written informed consent for study participation.

Eye movement recording

Eye movements were recorded using an eye-mark recorder (Nack, SK-2, Osaka, Japan) that consisted of two video cameras (left- and right-eye mark-shooting units) fixed to the left and right sides of a headband and another camera (field-shooting unit) fixed to the top of a helmet. Infrared light sources were positioned in front of each lower eyelid. The side cameras recorded the infrared light reflected from the cornea of the eye. The camera on the top of the helmet recorded the pictures shown on the screen. After a camera controller superimposed these three recordings with a 0.01-s electronic timer, the combined recording was saved on videotape. Movement of more than 1° with a duration greater than 0.1 s was scored as an eye movement. Poulton concluded from his study of the relation between eye movements and visual cognition that more than 0.2 s was required for the brain to process an image on the retina.10 Accordingly, the gazing point was determined from a gazing time exceeding 0.2 s. This technique enabled us to determine eye fixation points. Recorded data were assessed by a computer analysis system. Exploratory eye movements were analyzed for three parameters: mean gazing time (MGT) and total eye scanning length for gazing points (TESL).2,8,11 Eye scanning length was calculated from the distance between two eye gazing points.

Eye movement recording procedure

In a darkened room where visual sensory stimuli were attenuated, eye movement was recorded using the eye-mark recorder. Before eye movements were recorded, subjects were instructed to draw each subsequently viewed picture exactly as presented, except for picture 4 (a scene). All patients were also instructed to view and fix several corners’ points to check their eye movements to evaluate neurological deficits and low level eye movements as reflexogenic saccade, and all patients had no deficits in these procedure. Exploratory eye movements and fixation points during perception of pictures were examined. The pictures were projected onto a screen to form images 90 cm wide and 70 cm tall. Maximum angles of sight lines were 30° horizontally and 20° vertically. Each block consisted of a series of six pictures each presented for 15 s. Four kinds of picture were used as shown in Fig. 1. Picture 1 was a simple circle (to examine drive and motivation in subjects); and picture 2 was a ‘happy face’ (examining possible emotional influences). Picture 3 was a ‘happy face’ with lines added beside the mouth to examine recognition of differences. All subjects were asked the following question: are there any differences between this picture and the former one? They were also shown a picture identical to picture 3 (termed ‘picture 3*’)and given an oral instruction to search for any additional differences, to test confidence and attention. All subjects were asked ‘Are there any other differences?’ Picture 4 was a scene with 10 elements of different animals, the sun, an airplane, five similar trees, a house, two similar mountains, and a river, to examine eye movements involving simple attention targets, to test their visual ability, and short-term memory. All subjects were asked the following: ‘I ask what elements you saw in the picture after you closed it, thus, look at it carefully and remember’. Picture 5 was identical to picture 1 (an open circle) to examine influences from the preceding picture 4 representing habituation, as reported previously.8,11,12 For picture 4 all subjects were required to note all elements presented immediately after viewing. After viewing the six pictures, subjects were instructed to draw each picture except for picture 4 (a scene). We used these six pictures based on a circle except picture 4 to examine a set (picture 1), attention, confidence and search behavior (picture 2, 3, 3*) and to evaluate the eye movements for simple targets to check a reflexive saccade (picture 4) and to reevaluate the original picture (circle) as reported before.2 Exploratory eye movements were measured three times at an interval of 3 months: the first test was done within 2 weeks after admission in the acute groups.

image

Figure 1. The six pictures used in the present study. Typical series of the exploratory eye movements of acute phase patients (top), recovery phase patient (middle) and healthy subjects (bottom). Each dot indicates the gazing points. Note that the gazing points are located in the center of the picture especially for acute phase patients.

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Clinical evaluation and medication

The clinical state of all subjects was assessed using the Positive and Negative Symptom Scale (PANSS)13 by two psychiatrists not involved in the eye movement analysis; the positive symptom score was 26.9 ± 5.1 and the negative symptom score was 22.4 ± 5.1 All patients were treated with neuroleptics; their mean dose in chlorpromazine equivalents was 748 ± 385 mg per day.

Statistical analysis

For all obtained data, one-way repeated analysis of variance (anova) was performed to determine epsilon factors using G to G and H to F epsilon. The present study included acute patients (DP, AP), chronic patients (CP), and healthy subjects (HS). For data considered reliable (ɛ < 1.0), a two -way (session × picture) anova was used to compute the main session effect. Post hoc analyses were conducted using Scheffe tests. Next, a two-way anova (session × group) was used to examine the main session effect and the main group effect. Next, one-way anova (session) was used to examine the main session effect in each picture and each group. A level of P < 0.05 was accepted as statistically significant. The relationship between eye movement parameters and clinical variables or medication was tested using the Pearson product-moment correlation coefficient (r). Bartlett t-tests were used to confirm significance, defined as P < 0.05.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. REFERENCES

Typical sequences of the exploratory eye movements for one acute schizophrenic patient at the time of admission and 3 months after admission and for one healthy subject viewing six pictures are shown in Fig. 1. The patient had a clear disturbance of exploratory eye movements during the acute phase in comparison with the recovery phase or that of the healthy subject. The gazing points of schizophrenics were limited to the central portion of each picture except for the scene (picture 4). The gazing points expanded clearly in pictures, 1, 2, 3 and 5 after 3 months of treatment.

Mean gazing time

For schizophrenic acute patients, MGT was 0.55 ± 0.20 s and for CP it was 0.49 ± 0.14 s considering all sessions and pictures, while it was 0.41 ± 0.12 s for healthy subjects. The main session (first and at 3, and 6 months) difference by two-way anova (session ×  picture) was significant (F = 8.1; P < 0.001) and the main pictures difference was significant (F = 12.5; P < 0.001). The MGT for session 1 was significantly longer than for session 2 or 3 (P < 0.001). There were significant differences between the MGT of three sessions and those of healthy subjects. In picture 1 (first circle) there were significant differences between session 1 and session 3 (6 months later) (P < 0.05). In picture 3 (happy face with lines) there were significant differences between session 1 and sessions 2 and 3 (P < 0.01). In picture 5 (last circle) significant differences were obtained between session 1 and sessions 2 and 3 (P < 0.01). No significant session differences were obtained in pictures 2, 3* and 4. Significant differences of MGT were observed between session 3 and healthy subjects as shown in Fig. 2(b).

image

Figure 2. (Left) Mean gazing time (MGT; ordinate) was plotted against the sessions and healthy subjects (abscissa). The MGT were clearly prolonged at acute phase (session 1: S1). (⋆), significant differences between sessions; (*), and healthy subjects. ⋆⋆⋆P < 0.001; ***P < 0.001. (Right) MGT (ordinate) was plotted against each picture (abscissa). The MGT were clearly prolonged at acute phase (session 1: S1). (⋆), between sessions 1 and 2; (⋆), differences between session 1 and 3; (*), significant differences between session 3 and healthy subjects. ⋆⋆P < 0.01; ⋆P < 0.05; ⋆⋆P < 0.01; ⋆⋆⋆P < 0.001; **P < 0.01; ***P < 0.001.

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For DP, the MGT for session 1 was significantly longer than for sessions 2 (P < 0.01) and 3 (P < 0.001). In picture 1 (first circle) there were significant differences between session 1 and sessions 2 (P < 0.05) and 3 (P < 0.01). In picture 2 (happy face) there were significant differences between session 1 and sessions 2 and 3 (P < 0.05). In picture 3 (happy face with lines) there were significant differences between session 1 and sessions 2 (P < 0.05) and 3 (P < 0.01). In picture 5 (last circle) significant differences were obtained between session 1 and session 3 (P < 0.01). For AP, the MGT for session 1 was significantly longer than for session 3 (P < 0.001). In picture 1 there were significant differences between session 1 and sessions 2 and 3 (P < 0.05). In picture 5 significant differences were obtained between session 1 and sessions 2 (P < 0.05) and 3 (P < 0.01). For CP, there were significant session differences observed only in picture 5 (P < 0.05).

Total eye scanning length

For the schizophrenic groups considered together, the TESL was 105.2 ± 54.6 cm considering all pictures, which was significantly shorter than for healthy subjects (171.2 ± 75.7 cm). The main session difference by two-way anova was significant (F = 17; P < 0.001) and the main picture difference was (F = 57.6; P < 0.001). The TESL for session 1 was significantly smaller than for sessions 2 (P < 0.001) and 3 (P < 0.001). There were significant differences between the TESL of the three sessions and those of healthy subjects (P < 0.001). In picture 1 there were significant differences between session 1 and session 3 (P < 0.01). In picture 3 there were significant differences between session 1 and sessions 2 (P < 0.01) and 3 (P < 0.05). In picture 4 there were significant differences between session 1 and session 3 (P < 0.05). In picture 5 there were significant differences between session 1 and sessions 2 (P < 0.01) and 3(P < 0.01).

For DP, the TESL for session 1 was significantly shorter than that for sessions 2 and 3 (P < 0.001), and that for session 2 was significantly shorter than that for session 3 (P < 0.01) as shown in Fig. 3(a). In picture 1 there were significant differences between session 1 and session 3 (P < 0.01) and between session 2 and session 3 (P < 0.05). In picture 2 there were significant differences between session 1 and sessions 2 and 3 (P < 0.001). In picture 3 there were significant differences between session 1 and sessions 2 (P < 0.01) and 3 (P < 0.001). In picture 5 significant differences were obtained between session 1 and 3 (P < 0.05) and between session 2 and 3 (P < 0.05). For AP, the TESL for session 1 was significantly shorter than that for sessions 2 (P < 0.01) and 3 (P < 0.001). In picture 1 there were significant differences between session 1 and session 3 (P < 0.05). In picture 4 there were significant differences between session 1 and sessions 2 (P < 0.05) and 3 (P < 0.001). In picture 5 significant differences were obtained between session 1 and sessions 2 (P < 0.01) and 3 (P < 0.01). For CP there were no significant session differences observed.

image

Figure 3. (a) Mean gazing time (MGT) (ordinate) was plotted against the sessions in three groups (abscissa). (⋆), significant differences between sessions. The MGT were clearly and significantly shortened in discharged patients (DP; b) but not in chronic patients (CP; D). (⋆), significant differences between sessions 1 and 2; (⋆), significant differences between session 1 and 3. ⋆⋆P < 0.01; ⋆⋆⋆P < 0.001; ⋆P < 0.05; ⋆⋆P < 0.01; ⋆⋆⋆P < 0.001.

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Symptom scores

The overall mean negative symptom score for DP was 20.9 ± 4.3; for AP it was 23.4 ± 6.1 and for CP it was 22.5 ± 4.5. The mean positive symptom score for DP was 24.3 ± 4.1, for AP it was 27.8 ± 5.5 and for CP it was 27.9 ± 4.9. These scores became significantly decreased with each subsequent session in both DP and AP but not for CP. Negative symptom scores for all patients were positively correlated with MGT (r = 0.43, P < 0.001; DP, r = 0.54, P < 0.001; AP, r = 0.46, P < 0.001; CP, r = 0.39, P < 0.001). Negative symptom scores for acute patients were negatively correlated with MESL (r = −0.44, P < 0.001; DP, r = −0.43, P < 0.001; AP, r = −0.39, P < 0.001; CP, r = −0.48, P < 0.001). Negative symptom scores for acute patients were negatively correlated with TESL (r = −0.45, P < 0.001; DP, r = −0.53, P < 0.001; AP, r = −0.44, P < 0.001; CP, r = −0.42, P < 0.001). Positive symptom scores for all patients were positively correlated with MGT (r = 0.15, P < 0.01; DP, r = 0.22, P < 0.001; AP, r = 0.13, P < 0.05; CP, r = 0.25, P < 0.001). Those for acute patients were negatively correlated with MESL (r = −0.10, P < 0.05; DP, r = −0.20, P < 0.001; AP, r = −0.07, P = 0.20; CP, r = −0.01, P = 0.69). Positive symptom scores for acute patients were negatively correlated with TESL (r = −0.10, P < 0.05; DP, r = −0.29, P < 0.001; AP, r = −0.11, P = 0.50; CP, r = −0.07, P = 0.10). For each picture the correlation coefficients are shown in Table 1.

Table 1.   Correlation between total scanning length and symptom scores or doses of drugs
 GroupPicture 1Picture 2Picture 3Picture 3*Picture 4Picture 5
  • *

    P < 0.05;

  • **

    P < 0.01;

  • ***

    P < 0.001.

Negative symptom scoresAcute discharged−0.59***−0.75***−0.75***−0.57***−0.43***−0.61***
Acute admitted−0.77***−0.62***−0.37**−0.51***−0.26−0.67***
Chronic−0.51***−0.44***−0.41**−0.54***−0.47***−0.50***
Positive symptom scoresAcute discharged−0.34*−0.40**−0.38*−0.20−0.23−0.38*
Acute admitted−0.13−0.12−0.20−0.11−0.07−0.28
Chronic−0.10−0.06−0.21−0.05−0.05−0.25
DrugsAcute discharged−0.41**−0.42**−0.38*−0.16−0.12−0.24
Acute admitted−0.27 0.05 0.26 0.21−0.04−0.24
Chronic−0.06−0.18 0.33* 0.21−0.03−0.28

Neuroleptic dose

The overall chlorpromazine-equivalent neuroleptic doses for DP was 536 ± 247 mg/day; for AP it was 520 ± 271 mg/day and for CP it was 989 ± 345 mg/day, and these were not significantly different between sessions. The correlation coefficients between each eye measure and neuroleptic dose in each picture are shown in Table 1.

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. REFERENCES

The most important finding of the present study was that exploratory eye movements were clearly different between the acute and the remission phases in acute patients, but also still clearly different from those of healthy subjects, suggesting that the exploratory eye movements may be a useful biologic state and trait marker of schizophrenia. Kojima et al. investigated exploratory eye movements using specially constructed S-shaped geometric figures, demonstrating that schizophrenic patients had prolonged MGT and limited scanning.2 These investigators calculated a responsive search score (RSS) that was low only in schizophrenic patients, and advocated the RSS as being the most important parameter in exploratory eye movement studies. These authors concluded that the abnormality of exploratory eye movements resulted from a defect of attention, representing a possible trait marker for schizophrenia.7,14 In the present study we found that eye movements of schizophrenic patients had properties similar to those observed by Kojima et al.2 The present study also examined the clinical state of investigating abnormalities of eye movement in psychiatric patients. Specific aspects are discussed as follows.

Mean gazing time

The MGT for acute schizophrenic patients was significantly longer than that for chronic patients (Fig. 3a) and also for healthy subjects, suggesting that prolonged MGT may be a characteristic of the acute phase in schizophrenic patients. However, a significant difference in MGT was seen among sessions in acute patients, indicating that MGT may vary considerably with clinical state. The MGT differed significantly between all groups of patients and healthy subjects, again suggesting that abnormalities in exploratory eye movement were also a trait marker as reported previously.2 In all patients, pictures 1 (first circle), 3 (happy face with line) and 5 (last circle) may be more specific state-dependent stimuli than other stimuli in the present protocol. These may be due to the improvement of the set, also described as the drive (picture 1), due to an increased attention to recognize the differences (picture 3) and due to continued attention (picture 5). However, no significant changes were obtained in pictures 2 (happy face), 3*(happy face with lines added beside the mouth but otherwise identical to picture 3, and 4 (scene), suggesting several possibilities. One is that these defects were specific for schizophrenic patients owing to the disturbance in confidence given in picture 3*, which is essentially similar to RSS.2 The other possibilities are defects in affective cognition (picture 2) or interest (picture 4). In DP the MGT in pictures 1, 2, 3 and 5 improved significantly between sessions, suggesting again that this visual stimulus may be state dependent. However, the MGT in pictures 3* and 5 were not changed significantly, suggesting that these visual stimuli may not be state dependent. In AP the MGT in pictures 1 and 5 changed during the recovery period, indicating again that these pictures may be useful for measurement of the state dependency. The smaller difference in AP may be due to a severe defect in symptoms, indeed both the positive and negative symptom scores of AP were significantly larger that those of DP. Significant improvement was observed only in picture 5 for CP. This suggested that MGT might be changed only very slightly during 6 months for CP. Furthermore; picture 5 (last circle) may be the most useful state-dependent stimuli addition of the relationship of symptom scores.

Total eye scanning length

The TESL for schizophrenic patients were significantly shorter than those for healthy subjects, suggesting that limited scanning length may be a characteristic of schizophrenia as reported previously.2 However, because significant differences in both scanning lengths were seen among sessions, scanning length may vary considerably with clinical condition. The scanning length varied among sessions in pictures 1 (first circle) and 5 (last circle), suggesting that these more simple pictures may show more variability with the state of the illness. These findings also suggest that simple visual targets may be particularly useful for the exploratory eye movement studies involving state. These may be due to the improvement of the set, also termed ’the drive’ (picture 1) and also due to the increased attention to recognize the differences (picture 3), as suggested in the previous section. However, no significant changes were obtained for pictures 2 and 3*, indicating several possibilities as discussed in the previous section.

In DP the TESL in pictures 1, 2, 3 and 5 were improved significantly between session 1 and sessions 2 and 3, suggesting again that this visual stimulus may be state dependent. However, the TESL in pictures 3* and 4 were not significantly altered, thus indicating that they were state independent. In AP, the TESL in pictures 1, 4 and 5 were significantly changed during the recovery period, indicating that these patients may have had defects in the area of facial cognition. It is interesting that the TESL in picture 4 was significantly changed, suggesting that these patients may have improved visual function as regards nature scenes but not human faces. However, no significant changes were obtained in CP, suggesting that the present protocol may not improve the visual cognition. In the three groups there were no significant differences in pictures 2 and 3 for AP but there were significant differences in picture 4 for AP. From these findings it is suggested that reactions to pictures 2 and 3 may be due to social influences as outpatients.

Symptom and eye movements

Negative psychiatric symptoms have been reported to correlate negatively with exploratory eye movements.15 It was reported that a correlation coefficient > 0.5 was generally significant.16 In the present study, negative symptom scores of the PANSS were significantly correlated with the TESL in all patients and pictures, but the positive symptom scores were significantly correlated with the TESL only in the AP group (pictures 1,2,3,5). These findings suggest that exploratory eye movements may be biologic markers for negative symptoms such as emotional withdrawal, blunted affect, mannerisms, and posturing. This clinical correlation suggests that negative influence on eye movements might reflect underlying brain dysfunction, thus producing communicative deficits, disturbed relationships to the environment, and disturbed interpersonal relationships.15 Furthermore, correlation coefficients were > 0.5 with pictures 1 (first circle), 3* (confidence) and 5 (last circle) for the TESL. Thus, the TESL is the best measure to evaluate a patient's condition. These findings suggest that the circle may be useful for evaluating a state marker and the identical face (3*) may be useful for evaluating a trait marker as mentioned earlier.

Conclusions and physiologic significance

In the two eye movement measures (MGT, TESL) that were analyzed in the present study, significant differences were observed between all groups of schizophrenic patients (DP, AP, CP) and healthy subjects. Longer MGT and shorter TESL were obtained upon evaluation of fixation points as subjects viewed six simple pictures, suggesting that the exploratory eye movements may be a useful biologic trait marker. During the recovery period in the same acute schizophrenic patients, suggests that the exploratory eye movements may be a biologic state marker for evaluation of schizophrenia.

From the present results, the two eye movement measures were state-related in pictures 1,2,3,5 when subjects were instructed to draw each subsequently viewed picture exactly; and in picture 4 all subjects were required to note all elements presented immediately after viewing. However, the two eye movement measures were not related to state for picture 3*, accompanied by oral instructions to search for any additional differences and this condition is similar to that of the RSS reported by Kojima et al. These indicate the possibility that the former may be a state marker and the latter may be a trait marker. Based on the present observations, it is suggested that the schizophrenic patients may gaze at a certain part of a picture aimlessly rather than appropriately focusing their attention on a part of the picture. Shakow reported that schizophrenic patients could not concentrate their efforts towards external surroundings or proceed in a meaningful direction.17 This is based on the observation fixation points of inpatients, which tended to move within a particularly limited range. The present eye movement findings may provide an objective clue for understanding characteristics of everyday behavior in schizophrenic patients as well as their visual perception. These concepts were confirmed especially in outpatients after 6 months (DP). The present experimental conditions differed from those of Kojima et al.2 (including different pictures) although similar findings were observed. Significant negative correlation coefficients were obtained between TESL and negative symptom scores in all pictures, but significant positive correlation coefficients were obtained between TESL and positive symptom scores only in AD patients for pictures 1,2,3,5. Thus, the TESL is the best measure to evaluate a patient's condition. These findings suggest that the circle may be useful for evaluating a state marker and the identical face (3*) may be useful for evaluating a trait marker.

The TESL may be the best marker in terms of relationship to symptoms. Further evaluation of state-induced alterations of eye movement comparisons also should be made with other psychiatric patients such as those with mood disorders and anxiety disorders. Finally, the exploratory eye movements while viewing certain pictures are very different between schizophrenics and healthy subjects, and improve with remission. Thus, the exploratory eye movements suggest both state and trait markers and this is one of the best useful objective methods to evaluate schizophrenia.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. REFERENCES
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    Ryu H, Morita K, Shoji Y, Yaseda Y, Maeda Y. Abnormal exploratory eye movements in schizophrenic patients vs healthy subjects. Acta Neurol. Scand. 2001; 104: 369376.
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    Clementz BA, Sweeney JA. Is eye movement dysfunction a biological marker for schizophrenia? A methodological review. Psychol. Bull. 1990; 108: 7792.
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    Moriya H, Ando K, Kojima T et al. Eye movements during perception of pictures in chronic schizophrenics. Folia Psychiatry Neurosci. Jpn. 1972; 26: 189199.
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    Helmstadter GC. Principles of Psychological Measurements. Appleton-Century Crofts, New York, 1964.
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    Shakow D. Segmental set: A theory of the formal psychological deficit in schizophrenia. Arch. Gen. Psychiatry 1962; 6: 117.