Saccadic eye movement abnormalities in relatives of patients with schizophrenia

Recent studies note abnormalities in saccadic eye movements of relatives of patients with schizophrenia. The current study examined which aspects of the saccadic system are affected, whether these saccadic abnormalities are associated with schizophrenia spectrum personality symptoms (SSP), and whether such an association is dependent on a family history of schizophrenia. Furthermore, the study examined what proportion of relatives have the saccadic abnormality(ies). Fifty-five first-degree relatives with no DSM-III-R Axis I diagnosis participated in the study. Twenty-one of these relatives experienced SSP symptoms and 34 had no Axis II diagnosis. Sixty-two subjects with no Axis I diagnosis were recruited from the community. Twenty-five experienced SSP symptoms and 37 had no Axis II diagnosis. Prosaccades (saccades toward the target) and antisaccades (saccades made in the opposite direction of the target jump) were examined. Relatives, particularly those with SSP, had difficulties with the antisaccade task as suggested by higher error rates and longer antisaccade latency. Prosaccades were not different in relatives compared to the community subjects, although the effects of field were different in the two groups on some measures. The antisaccade latency was 'abnormal' in only a small proportion (1.6%) of community subjects compared to 14.9% of all relatives (35.3% of SSP relatives and 3.3% of non-SSP relatives). Relatives of patients with schizophrenia have deficits in aspects of the saccadic system involved in generating internally driven saccades and inhibition of unwanted saccades. These deficits implicate frontal ocular motor neuronal circuitry involving frontal cortical and basal ganglia areas. These deficits are associated with SSP symptoms, but not in the absence of a blood relationship to schizophrenia. The relatively high prevalence rate of the abnormality in at-risk subjects may have relevance for use of these measures in linkage analysis.

Modulation of the startle response and startle laterality in relatives of schizophrenic patients and in subjects with schizotypal personality disorder: evidence of inhibitory deficits

OBJECTIVE

Patients with schizophrenia spectrum disorders have been shown to have deficits in sensorimotor gating as assessed by prepulse inhibition of the startle response. The authors hypothesized that nonschizophrenic relatives of patients with schizophrenia would also have prepulse inhibition deficits, thereby reflecting a genetically transmitted susceptibility to sensorimotor gating deficits.

METHOD

Twenty-five comparison subjects, 23 patients with schizophrenia, 34 relatives of the schizophrenic patients, and 11 subjects with schizotypal personality disorder were assessed in an acoustic startle paradigm. The eye-blink component of the startle response was assessed bilaterally by using electromyographic recordings of orbicularis oculi.

RESULTS

The patients with schizophrenia, their relatives, and subjects with schizotypal personality disorder all had reduced prepulse inhibition relative to comparison subjects, and these deficits were more evident in measures of right eye-blink prepulse inhibition. Comparison subjects demonstrated greater right versus left eye-blink prepulse inhibition, whereas the probands, their relatives, and subjects with schizotypal personality disorder showed less asymmetry of prepulse inhibition.

CONCLUSIONS

These data suggest a genetically transmitted deficit in prepulse inhibition (sensorimotor gating) in patients with schizophrenia spectrum disorders, including subjects with schizotypal personality disorder and relatives of patients with schizophrenia.

A double-blind, placebo-controlled study of risperidone addition in serotonin reuptake inhibitor-refractory obsessive-compulsive disorder

BACKGROUND

To date, only 1 controlled study has found a drug (haloperidol) to be efficacious in augmenting response in patients with obsessive-compulsive disorder (OCD) refractory to serotonin reuptake inhibitor (SRI) monotherapy; patients with comorbid chronic tic disorders showed a preferential response. This report describes the first controlled study of risperidone addition in patients with OCD refractory to treatment with SRI alone.

METHODS

Seventy adult patients with a primary DSM-IV diagnosis of OCD received 12 weeks of treatment with an SRI. Thirty-six patients were refractory to the SRI and were randomized in a double-blind manner to 6 weeks of risperidone (n = 20) or placebo (n = 16) addition. Behavioral ratings, including the Yale-Brown Obsessive Compulsive Scale, were obtained at baseline and throughout the trial. Placebo-treated patients subsequently received an identical open-label trial of risperidone addition.

RESULTS

For study completers, 9 (50%) of 18 risperidone-treated patients were responders (mean daily dose, 2.2 +/-0.7 mg/d) compared with 0 of 15 in the placebo addition group (P<. 005). Seven (50%) of 14 patients who received open-label risperidone addition responded. Risperidone addition was superior to placebo in reducing OCD (P<.001), depressive (P<.001), and anxiety (P =.003) symptoms. There was no difference in response between OCD patients with and without comorbid diagnoses of chronic tic disorder or schizotypal personalty disorder. Other than mild, transient sedation, risperidone was well tolerated.

CONCLUSION

These results suggest that OCD patients with and without comorbid chronic tic disorders or schizotypal personality disorder may respond to the addition of low-dose risperidone to ongoing SRI therapy.

Dissociation, schizotypy, and fantasy proneness in undergraduate students

Previous research has noted a robust correlation between dissociation and schizophrenia-like symptoms. One way to interpret the relationship between dissociation and schizotypy is to assume that it is an artifact of fantasy proneness. In the present study, 152 undergraduates completed measures of dissociation, schizotypy, and fantasy proneness. Dissociative tendencies were found to be related to the full range of schizotypal features. Regression analysis showed that schizotypy still contributed to the prediction of dissociative tendencies when variance related to fantasy proneness was extracted. These results indicate that the close connection between dissociation and schizotypy cannot be interpreted in terms of an artifact produced by fantasy proneness. Thus, the overlap between dissociation and schizotypy warrants systematic study.

Smooth pursuit eye tracking and visual fixation in psychosis-prone individuals

Subjects identified by Perceptual Aberration-Magical Ideation (Per-Mag) scores (n=97), Social Anhedonia (SocAnh) scores (n=45), and Physical Anhedonia (PhysAnh) scores (n=31) as well as normal controls (n=94), underwent psychophysiological and clinical assessment. This is the first published investigation of pursuit system functioning in three groups of questionnaire-identified at-risk individuals. Pursuit during a simple non-monitor tracking task was measured using root-mean-square error (RMSE) scores and pursuit gain scores. Fixation performance was measured in terms of number of saccades away from the central fixation point. The at-risk subjects were more likely to display aberrant smooth pursuit tracking than controls, though there were no significant differences between the at-risk subjects endorsing items relevant to positive-symptom schizotypy and those endorsing items pertaining to negative-symptom schizotypy. The groups did not differ significantly in their visual fixation performance. Participants were also evaluated for the presence of Axis I symptomatology and psychotic-like experiences. Neither the experimental subjects nor the control subjects displayed a significant association between ocular motor performance and psychotic-like experiences. These findings are consistent with prior evidence that pursuit tracking is a trait characteristic, independent of clinical status.

Co-occurrence of Axis I and Axis II disorders in substance abusers

OBJECTIVE

This study examined the co-occurrence of anxiety/mood and personality disorders (PDs) in substance abusers, the impact of anxiety/ mood disorders on the symptom profiles of PDs, and the impact of anxiety/mood disorders and PDs on pre-treatment status.

METHOD

Current anxiety/mood disorders and PDs and pre-treatment status were assessed using semi-structured interviews in 370 treated substance abusers.

RESULTS

Anxiety/mood disorders and PDs frequently co-occurred, with the overall pattern of associations being non-specific. The strongest associations were of social phobia with avoidant and schizotypal PD, and of major depression with borderline PD. However, symptom profiles of PDs were not associated with anxiety/mood disorders. Finally, anxiety/mood disorders and PDs were both independently and differentially associated with poor pre-treatment characteristics.

CONCLUSION

The findings suggest the clinical importance of obtaining both Axis I and Axis II diagnoses in treated substance abusers, and highlight the distinctiveness of the Axis I and Axis II disorders.

Phenotypic characteristics of Obsessive-Compulsive Disorder ascertained in adulthood

Over the past decade, the increased awareness and knowledge of Obsessive-Compulsive Disorder (OCD) has allowed the in-depth study of its phenotypic characteristics. The largest studies to date have described the symptom and syndrome characteristics of treatment-seeking patients. While usefully homogeneous with regard to their current state, the clinical characteristics of patients seeking treatment may only partially represent the OCD population. We report findings from 100 self-selected volunteers at various stages of their OCD illness who were participating in a genetic study. Many similarities with past reports were found, including high rates of mood disorder, significantly more mood disorder in females as compared with males, and increased social impairment among males despite an equal amount of time in episodes of disorder. On the other hand, mean age of onset in this nontreatment seeking population was younger. Lifetime rates of obsessions and compulsions in this population were substantially higher than previous reports, suggesting that the content of obsessions and compulsions shifted over time, and evolved into a lifetime repertoire. Furthermore, a separate analysis of the age of clinically significant O-C symptom onset without impairment revealed that males and females did not differ, suggesting that previous reports of earlier onset age in males may actually reflect earlier onset of impairment. Future genetic studies may benefit from the analysis of both significant O-C symptom onset, as well as the onset of full-syndromal OCD. These findings may suggest phenotypic characteristics that define homogeneous subgroups of patients with OCD.

Communication disturbances and family psychiatric history in parents of schizophrenic patients

Parents of schizophrenic patients have demonstrated subtle disturbances of thought, language, and communication. The etiologic relevance of these disturbances is not clear. This study assessed levels of referential communication disturbance in the "natural speech" of schizophrenic patients, nonschizophrenic parents of patients, and control subjects matched to the patients' parents and tested for associations of communication disturbances in parents with family history of psychosis and with schizotypy scale scores. The speech of the patients' parents as a group contained high frequencies of referential failures. Those parents with first-degree family histories of psychosis and/or high schizotypy scale scores made more frequent referential failures than the rest of the parents. Family history was particularly highly associated with failures involving language structural breakdown. The results of this study suggest that referential disturbances in parents of patients may be related to genetic liability in the parents. However, such an effect does not appear to account fully for the sizable differences between parents and controls in levels of communication disturbance.

Sustained attention deficit and schizotypal personality features in nonpsychotic relatives of schizophrenic patients

OBJECTIVE

The authors investigated whether nonpsychotic relatives of schizophrenic probands have an elevated risk of deficits in sustained attention as measured by the Continuous Performance Test (CPT), whether such deficits are associated with specific factors of schizotypy, and whether poor CPT performance by probands predicts poor performance by their relatives. In addition, the heritability of CPT performance in the families of schizophrenic probands was estimated.

METHOD

The study subjects were 60 schizophrenic probands, 148 of their first-degree relatives, 20 normal comparison probands, and 42 of the comparison probands' first-degree relatives. Subjects completed undegraded and 25% degraded sessions of the CPT and were interviewed with use of the Chinese version of the Diagnostic Interview for Genetic Studies. Subjects' CPT sensitivity indexes, d', were standardized against those of a community sample of 345 subjects, with adjustment for age, sex, and level of education.

RESULTS

On average, the d' values of the relatives of schizophrenic probands were lower than those of the relatives of comparison probands but higher than those of schizophrenic probands. Lower sensitivity indexes among the relatives of schizophrenic patients were associated with the interpersonal dysfunction and disorganization factors of schizotypy but not the cognitive/perceptual factor. When schizophrenic probands were divided into two subgroups by a cutoff of -3.0 for adjusted z score on the CPT, the d' values of relatives of probands with CPT deficits were lower than those of relatives of probands without deficits. The estimated heritability of performance on the CPT ranged from 0.48 to 0.62.

CONCLUSIONS

Sustained attention deficit may be a genetic vulnerability marker for schizophrenia, and it may be more useful in linkage analysis than traditional phenotype definitions of schizophrenia.

Smooth pursuit eye movements to extraretinal motion signals: deficits in relatives of patients with schizophrenia

BACKGROUND

Although mounting evidence supports the idea that smooth pursuit abnormality marks the genetic liability to schizophrenia, the precise ocular motor mechanism underlying the abnormality remains unknown. Based on recent findings in schizophrenia, we hypothesize that subtle deficits in the ability to hold online and/or use extraretinal motion information underlie the pursuit abnormality in vulnerable individuals.

METHODS

The hypothesis was tested in 69 first-degree, biological relatives of probands with schizophrenia; 26 relatives had schizophrenia spectrum personalities (SSP). Subjects recruited from the community (n=71; 29 with SSP), without a known family history of psychosis, constituted the comparison groups. The traditional smooth pursuit gain measure, which is a ratio of smooth pursuit eye velocity in response to both retinal and extraretinal motion signals and the target velocity, was obtained. In addition, newly developed measures of predictive smooth pursuit (ie, in the presence of only extraretinal motion signals) were obtained. The latter measures were evaluated after the current retinal motion signals were made unavailable by briefly making the target invisible.

RESULTS

Relatives, particularly those with SSP, showed significantly poorer predictive pursuit response to extraretinal motion signals (F(2,136)=6.51, P<.005), compared with the community subjects. However, the traditional smooth pursuit gain in response to both retinal and extraretinal motion signals was not different between groups.

CONCLUSIONS

These results suggest that relatives of patients with schizophrenia, particularly those with SSP, have specific deficits in predictive pursuit based on only extraretinal motion signals. Normal smooth pursuit gain in response to both retinal and extraretinal motion signals is likely due to compensation based on retinal motion information. The latter suggests normal retinal motion processing and smooth pursuit motor output.

Spontaneous dyskinesia in subjects with schizophrenia spectrum personality

OBJECTIVE

The study of spontaneous dyskinesia in schizophrenia is confounded by the widespread use of neuroleptics. The authors hypothesized that spontaneous dyskinesia would be present in subjects with schizophrenia spectrum personality (schizoid, paranoid, or schizotypal). They also tested the hypothesis that dyskinetic-like movements would increase after repeated dextroamphetamine challenge to the dopaminergic system.

METHOD

Dyskinetic-like movements were assessed in 34 spectrum subjects and 22 normal subjects; nine subjects from each group were administered both placebo and repeated dextroamphetamine challenges.

RESULTS

Spectrum subjects had more dyskinetic-like movements than normal subjects. Spontaneous dyskinesia was present in 12% of the spectrum subjects but was not seen in the normal subjects. Subjects with schizotypal personality had more dyskinetic-like movements than subjects with schizoid personality or normal subjects. Dyskinesia was present in 24% of the schizotypal subjects but not in the other groups. Dyskinetic movement scores correlated with positive symptom scores. With repeated amphetamine challenge, normal subjects showed a pattern of behavioral sensitization (an increase in dyskinetic-like movements), but spectrum subjects showed an abnormal response (fewer dyskinetic-like movements).

CONCLUSIONS

Dyskinesia and dyskinetic-like movements are more common in subjects with schizophrenia spectrum personality (primarily schizotypal) than in normal subjects and are related to positive symptoms. A failure of normal behavioral sensitization mechanisms after dextroamphetamine challenge is seen in subjects with schizophrenia spectrum personality.

Maternal demographic correlates of increased history of obstetric complications in schizophrenia

Evidence that history of obstetric complications (OCs) may contribute to the development of schizophrenia has generated renewed focus on characteristics of mothers of preschizophrenics. We studied the relationship between increased history of obstetric complications (OCs) and maternal age, parity, and social class in 70 Research Diagnosis Criteria schizophrenic patients vs 70 demographically matched controls. The sample has previously been studied concerning OC rates in schizophrenic patients, their relationship to other presumptive etiological factors, as well as head circumference at birth. Parity was the only maternal characteristic significantly associated with increased OCs in mothers of preschizophrenics. As compared with nulliparous control mothers, nulliparous mothers of preschizophrenics had significantly increased rates of total OCs and labour/delivery complications, while primi- and multiparous mothers of preschizophrenics (vs parity-matched control mothers) did not have increased rates of OCs. Abnormal labour length was significantly increased in the nulliparous mothers of preschizophrenics. Previous findings of significantly reduced head circumference at birth in preschizophrenic neonates vs controls were reconfirmed selectively in the nulliparous group.

Epidemiology of schizophrenia

OBJECTIVE

To characterize the epidemiology of schizophrenia.

METHOD

Narrative literature review.

RESULTS

Each year 1 in 10,000 adults (12 to 60 years of age) develops schizophrenia. Based on a restrictive and precise definition of the diagnosis and using standardized assessment methods and large, representative populations, the incidence rates appear stable across countries and cultures and over time, at least for the last 50 years. Schizophrenic patients are not born into ecological and social disadvantage. The uneven distribution of prevalence rates is a result of social selection: an early onset leads to social stagnation, a late onset to descent from a higher social status. The main age range of risk for schizophrenia is 20 to 35 years. It is still unclear whether schizophrenia-like late-onset psychoses (for example, late paraphrenia) after age 60 should be classified as schizophrenia either psychopathologically or etiologically. In 75% of cases, first admission is preceded by a prodromal phase with a mean length of 5 years and a psychotic prephase of one year's duration. On average, women fall ill 3 to 4 years later than men and show a second peak of onset around menopause. Consequently, late-onset schizophrenias are more frequent and more severe in women than in men. The sex difference in age of onset is smaller in cases with a high genetic load and greater in cases with a low genetic load. Type of onset and core symptoms do not differ between the sexes. The most pronounced sex difference is the socially negative illness behaviour of young men.

CONCLUSIONS

Among the factors determining social course and outcome are level of social development at onset, the disorder itself (for example, genetic liability, severity of symptoms, and functional deficits), general biological factors (for example, estrogen), and sex- and age-specific illness behaviour.

Gender differences in personality disorders in psychiatrically hospitalized young adults

We examined gender differences in DSM-III-R personality disorders in psychiatrically hospitalized young adults. Structured diagnostic interviews were reliably performed on a consecutive series of 118 inpatients. Men were significantly more likely to meet criteria for cluster A, schizotypal, and antisocial personality disorders. To reduce variability due to axis I heterogeneity, we retested for gender differences in a subgroup of patients with major depression. Depressed men were more likely to meet criteria for cluster A, schizotypal, and cluster C personality disorders. Women were not observed to have a higher frequency of any personality disorder than men in either study group.

Relationship of obsessive-compulsive symptomatology to anxiety, depression and schizotypy in a clinical population

The relationship of obsessive-compulsive symptomatology to anxiety disorders, mood disorders and schizophrenia continues to be controversial. In a sample of 117 psychiatric out-patients, we examined the relationship of obsessive-compulsive symptomatology to indices of anxiety, depression and schizotypy. The relationship between obsessive-compulsive symptomatology and schizotypy was found to be significantly higher than that between obsessive-compulsive symptoms and either anxiety or depression. These findings are consistent with recent studies suggesting that there are similar cognitive deficits associated with obsessive-compulsive symptoms and schizotypy and that obsessive-compulsive disorders may be more closely aligned to the schizophrenic constellation of disorders than to anxiety disorders.

The molecular genetics of schizophrenia

There is overwhelming evidence for a significant genetic contribution to the etiology of schizophrenia. Molecular genetic techniques are now sufficiently advanced to be applied to complex genetic disorders with uncertain phenotypes, such as schizophrenia. In this article we first briefly discuss certain pertinent background issues: the evidence that schizophrenia has a heritable basis, the possible modes of inheritance involved, and how best to define schizophrenia in the light of this evidence; we then review the current status of research in the field. Large collaborative studies are currently underway that pave the way for the detection of genes of both major and minor effects. We may now be seeing the first consistently replicated results from chromosome 6 and 22 and from candidate genes, such as the dopamine D3 receptor gene.

Testing the effect of season of birth on familial risk for schizophrenia and related disorders

BACKGROUND

An excess of late winter and early spring births in schizophrenia has been repeatedly demonstrated. Previous evidence has suggested that the risk for schizophrenia may differ in relatives of schizophrenic probands born in this high risk period v. at other times of the year.

METHOD

In an epidemiologically based family study conducted in the west of Ireland, we examined the relationship between season of birth in schizophrenia and schizophrenia spectrum probands and the risk for schizophrenia and related disorders in first-degree relatives. Risk was assessed using the Cox proportional hazard method. We examined four birth seasons previously shown to significantly predict risk for schizophrenia.

RESULTS

Neither the risk for schizophrenia nor that for schizophrenia spectrum disorders in relatives was significantly associated with season of birth in probands.

CONCLUSIONS

Season of birth does not, in this sample, identify schizophrenic probands with particularly high or low familial vulnerability to illness.

Familial risks and reproductive fitness in schizophrenia

Recently published data from the Roscommon Family Study show that a parental diagnosis of schizotypal disorder (SPD) has a significant and specific impact on the risk for schizophrenia in siblings of index probands with schizophrenia spectrum disorders. The distribution patterns of risks for schizophrenia and SPD in parents were of opposite magnitude to those of patients' siblings and children. These patterns can be predicted from the diminished reproductive fitness of patients with schizophrenia if subjects with SPD belong in the schizophrenia spectrum but have no diminished fitness. We briefly review how the few available data about the distribution of risks for schizophrenia and SPD among relatives of probands with SPD and the data for their marital status, as a tentative index of reproductive fitness, may support this interpretation. There is some indirect evidence that, unlike what is usually reported for people with schizophrenia, reproductive fitness may not be diminished in SPD. This might partially account for the opposite patterns of distribution of risks for schizophrenia and SPD in families.

[Do alcohol or drug abuse induce schizophrenia?]

The high comorbidity of schizophrenia and substance abuse raises the question of a causal relationship between the two disorders. Clarifying the temporal sequence of their onsets can shed light on this issue. For this purpose, onset and course of schizophrenic symptoms and of alcohol and drug abuse were retrospectively investigated within the ABC Schizophrenia Study in a representative first-episode sample of 232 schizophrenic patients. The rates of alcohol abuse (24%) and of drug abuse (14%) were twice the rates compared to the general population but schizophrenic patients seemed to have started substance abuse later than the control group. Male sex and early symptom onset were major risk factors. At all important landmarks during the early course of schizophrenia, drug-abusers were younger than alcohol-abusers who were younger than non-abusers. Alcohol abuse usually started during the prodromal phase, i.e., after the first sign of schizophrenia but before the first positive symptom. Drug abuse emerged before the first symptom in one third, simultaneously with it in another third, and during the prodromal phase in the last third of patients. Drug abuse significantly preceded the psychotic phase. The hypothesis that substance abuse causes schizophrenia thus is not generally supported. Findings on symptomatology illustrate the problems substance-abusing schizophrenics pose from early on with dissocial behaviors and preoccupation with magical ideas but without a specific positive or negative subsyndrome.

Gender differences in schizotypic features in a large sample of young adults

Research with self-report measures of schizotypic or psychosis-prone features in nonclinical populations suggests that, similarly to schizophrenic populations, males score higher on more "negative" schizotypic features and females score higher on more "positive" schizotypic features. We administered the Schizotypal Personality Questionnaire and the Chapman Scales of Psychosis Proneness--impulsivity/nonconformity, magical ideation, perceptual aberration, physical anhedonia, and social anhedonia--to a large, nonclinical, young adult sample (N = 1179: 453 males and 726 females). Results indicated increased negative symptomatology in males compared with females, but not increased positive symptomatology in females compared with males. Findings on Schizotypal Personality Questionnaire factors suggested that interpersonal deficits differed by gender as well. Finally, a measure of impulsive behavior and nonconformity not typically associated with negative symptomatology indicated gender differences not predicted by a negative/positive dichotomy.

Predictors of drug treatment response in obsessive-compulsive disorder

BACKGROUND

Although a large body of evidence indicates the efficacy of pharmacotherapy in the treatment of obsessive-compulsive disorder (OCD), a considerable percentage of these patients do not respond. Very few studies focus on factors related to treatment response of OCD. The purpose of this study was to investigate which clinical factors are related to drug treatment response in OCD.

METHOD

We examined 53 OCD patients treated with either clomipramine or fluoxetine for a period of 6 months, dividing the sample into "responders" and "nonresponders" to treatment. At admission, patients were evaluated using a semistructured clinical interview, the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the Hamilton Rating Scale for Depression, and the Hamilton Rating Scale for Anxiety. We then compared acute-phase patient characteristics and response to drug treatment. Response was defined as a decrease of at least 40% in the Y-BOCS total score and a rating of "improved" or "very improved" on the Clinical Global Impressions scale within 16 weeks of treatment and maintained over three consecutive evaluations.

RESULTS

By the sixth month of treatment, 31 patients (58.5%) responded to either clomipramine or fluoxetine. Nonresponders had lower age at onset and longer duration of the disorder; in addition, they showed higher frequency of compulsions, washing rituals, chronic course, concomitant schizotypal personality disorder, and previous hospitalizations. A worse response to drug treatment was predicted in a stepwise multiple regression by (1) concomitant schizotypal personality disorder, (2) presence of compulsions, and (3) longer illness length.

CONCLUSION

Our findings suggest that there are distinct types of OCD with respect to drug treatment response. They provide indirect evidence of treatment specificity by identifying characteristics responsive to different modalities, which may be of value in the selection of patients for alternative treatments.

Evaluating the spectrum concept of schizophrenia in the Roscommon Family Study

OBJECTIVE

The authors sought to evaluate whether the pattern of schizophrenia and related disorders in probands and their relatives can be explained by a single underlying continuum of liability to the "schizophrenia spectrum."

METHOD

In the epidemiologically based Roscommon Family Study, the authors separately examined--in siblings, parents, and relatives of index and comparison probands--the familial aggregation and coaggregation of five hierarchically defined disorders: schizophrenia, schizoaffective disorder, schizotypal/paranoid personality disorder, other nonaffective psychoses, and psychotic affective illness. A multiple threshold model was fitted to these contingency tables by maximum likelihood.

RESULTS

The multiple threshold model that constrained resemblance to be the same in siblings and parents fit the data well and estimated the correlation in liability to schizophrenia spectrum disorders between probands and first-degree relatives at 0.36. Parents, however, required higher levels of liability to manifest schizophrenia spectrum disorders than siblings. While schizophrenia and psychotic affective illness could be clearly assigned to the two extremes of the schizophrenia spectrum, the proper ordering of schizoaffective disorder, schizotypal/paranoid personality disorder, and other nonaffective psychoses could not be unambiguously determined.

CONCLUSIONS

These results are consistent with the existence of a schizophrenia spectrum in which these five disorders are manifestations, of varying severity, of the same underlying vulnerability. This vulnerability is strongly transmitted within families.

Schizotypal symptoms and signs in the Roscommon Family Study. Their factor structure and familial relationship with psychotic and affective disorders

BACKGROUND

Although schizotypal personality disorder aggregates in relatives of schizophrenic probands, the criteria for this disorder may not be optimal either in describing the dimensions of schizotypal phenomena or in identifying those with a high familial liability to schizophrenia.

METHODS

In the Roscommon Family Study, an epidemiologically based family study of major psychiatric disorders conducted in the west of Ireland, we examined 25 individual schizotypal symptoms and signs, assessed by structured personal interview, in 1544 first-degree relatives (without chronic psychosis or mental retardation) of five proband groups: schizophrenia; other nonaffective psychoses; psychotic affective illness; nonpsychotic affective illness; and matched, unscreened controls.

RESULTS

We obtained seven meaningful schizotypal factors: negative schizotypy, positive schizotypy, borderline symptoms, social dysfunction, avoidant symptoms, odd speech, and suspicious behavior. Taken individually, all of these factors, except borderline symptoms, significantly discriminated relatives of schizophrenic probands from relatives of controls; in descending order of the odds ratios, they were odd speech, social dysfunction, suspicious behavior, negative schizotypy, avoidant symptoms, and positive schizotypy. In a multivariate analysis, four of these factors remained significant: odd speech, negative symptoms, social dysfunction, and avoidant symptoms. These schizotypal factors differed in their specificity. Three of the four most predictive schizotypal factors also significantly discriminated relatives of probands with other nonaffective psychoses from relatives of controls.

CONCLUSION

"Schizotypy" is a complex, multidimensional clinical construct, whose various dimensions differ widely both in the degree and specificity with which they reflect the familial liability to schizophrenia. Subpsychotic thought disorder; negative schizotypal signs, such as poor rapport and odd behavior; deficient occupational functioning; and social isolation/avoidance best characterized relatives of schizophrenic probands compared with relatives of matched controls.