Difference in reaction time between subjects with schizotypal and borderline personality disorders

Information processing and attentional dysfunctions as vulnerability indicators in schizophrenia spectrum disorders

The schizotypal personality disorder is believed to be part of the schizophrenic spectrum of disorders including schizophrenic patients as well as some of their seemingly unaffected relatives with discreet symptoms. Spectrum-individuals are characterised by a genetic vulnerability for schizophrenia. The vulnerability is connected with neurocognitive deficits independent of clinical state. Some cognitive dysfunctions are unspecific and probably related to non-genetic brain damage. A consistent finding has, however, been poor performance in tasks involving information processing and attention. The findings point to the existence of specific sensory-perceptual deficits or a general attentional dysfunction. Identification of cognitive disturbances characteristic not only of schizophrenics, but also of schizotypal disordered and their relatives in the boundaries of schizophrenia, is relevant in order better to understand the pathogenetic mechanisms and treatment of schizophrenia. In the present review clinical data are analysed based on models of vulnerability and information processing with reference to a characterisation of the neuro-integrative deficits that form the core abnormalities of the spectrum.

Motor dysfunction in schizotypal personality disorder

Past research has revealed that schizophrenia is associated with voluntary movement abnormalities, as well as higher rates of involuntary movements. On instrumental motor tasks, patients manifest reduced motor stability, excessive force and more contralateral motor overflow (movement in the non-responding hand). In the present study, an instrumental motor task (manual response forced-choice task) was administered to a group of adults with schizotypal personality disorder (SPD) in order to determine whether they show motor deficits similar to those observed in schizophrenia. As predicted, the schizotypal subjects were excessive and more variable in motor force, compared to healthy controls and other personality-disordered subjects. Additionally, the force and variability of the motor responses were positively correlated with ratings of both positive and negative SPD symptoms. Finally, motor overflow and negative symptoms were associated with higher salivary cortisol levels. The pattern of findings is consistent with previous reports linking motor abnormalities and heightened cortisol with schizotypal personality disorder.

Positive and negative schizotypal symptoms relate to different aspects of crossover reaction time task performance

Although the expressions of both positive and negative symptoms in schizophrenia spectrum illnesses can each occur with varying degrees of severity, researchers have often dichotomized patients as generally positive or negative subtypes. Studies of schizophrenia and schizotypal personality disorder (SPD) have not typically controlled for the severity of the other symptom types when examining the relationship between positive and negative symptom subtypes and cognitive impairment. The present study investigated the relationship between the severity of both symptom types and reaction time crossover task performance in SPD in groups made equivalent on the severity of the other type of symptom. Fifty-eight out of 458 undergraduates were screened into one of four groups (high negative-high positive, low negative-low positive, high negative-low positive or low negative-high positive) by the Schizotypal Personality Questionnaire and assessed with the reaction time crossover task. The results indicated that negative schizotypal symptoms were associated with the early crossover pattern, while positive schizotypal symptoms related to longer overall reaction time. Therefore, different cognitive mechanisms involved in crossover task performance appeared to be associated with different symptom subtypes.

Normalizing the crossover effect: enhancement of cognitive attentional processing in schizophrenia

Thirty male schizophrenic subjects and 20 male control subjects were administered both the classic Rodnick and Shakow reaction time (RT) procedure and a modified experimental procedure using a balanced design in an attempt to enhance cognitive attentional processing and inhibit the crossover effect in schizophrenic patients. The experimental procedure increased the number of predictable trials, provided more information about the task and presented the regular trials in a simple ascending order. Analysis of the RT data showed the typical early schizophrenic crossover and late normal crossover on the standard task, while schizophrenic patients in the experimental condition showed a new finding of statistically significant normalization of the early crossover effect. The results support Shakow's theory of attentional set deficit in schizophrenia and in conjunction with previous findings suggest that separate neuropsychological mechanisms of cognitive preparatory attention and a more automatic form of vigilance attention may, respectively, underlie the regular and irregular procedures of the traditional RT task.

Clinical and experimental characteristics of "hypothetically psychosis prone" college students

The study of individuals at the boundaries of schizophrenia has historically involved genetic relatives of schizophrenia patients or individuals who meet criteria for schizotypal personality disorder (SPD). Recently, many investigators have turned to the use of psychometric scales, developed to measure psychotic traits or vulnerability to developing schizophrenia, to screen large populations of college students in order to identify individuals who are "psychosis prone" or "schizotypal". To help answer the question of whether students identified with psychometric scales are indeed psychosis prone, we screened 1115 college students with the Perceptual Aberration/ Magical Ideation (PerMag) and Physical Anhedonia (PhysAn) Scales. Individuals who scored 2 standard deviations (SD) above the mean on the scales were selected as experimental subjects (N = 13 PerMag, N = 10 PhysAn) and a subpopulation of matched subjects who scored less than 0.5 SD above the mean were selected as control subjects (N = 24). All subjects then received a full battery of tests, including structured clinical interviews, the MMPI, and psychophysiological measures of information processing, including prepulse inhibition and habituation of the human startle response, visual backward masking and reaction time measures. The results suggest that the PerMag scale, but not the PhysAn scale, identifies individuals with some psychotic, affective and anxiety symptoms when compared to the controls. Neither scale predicts a diagnosis of schizotypal personality disorder or deficits on measures of information processing that characterize schizophrenia or schizotypal personality disordered patients.

Psychosis proneness scales in schizophrenia spectrum personality disorders: familial vs. nonfamilial samples

The authors evaluated the extent of overlap between DSM-III-R schizophrenia spectrum personality diagnoses (SSPD) and the Psychosis Proneness Scales of Chapman and his associates. The subjects were recruited from the family members of schizophrenic patients ("familial" subjects; n = 45) and members of the community with negative family histories for schizophrenia ("nonfamilial" subjects; n = 60). Clinical interviews were performed to obtain DSM-III-R Axis I and II diagnoses. In 105 individuals with no Axis I diagnosis, the five Chapman Scales were administered. The results suggest that the nonfamilial subjects with diagnoses of SSPD (n = 24) scored significantly higher on the Chapman Scales of Magical Ideation, Perceptual Aberration, and Impulsive Nonconformity compared with the familial SSPD subjects and the other non-SSPD groups. The familial SSPD subjects (n = 17) scored significantly higher than the nonfamilial, non-SSPD groups on the Physical Anhedonia Scale. Scores on the Social Anhedonia Scale were highest in the SSPD subjects, but only scores for the nonfamilial SSPD subjects were statistically different from those for the other non-SSPD groups. The data were reanalyzed by first dividing the scores from the Chapman Scales into high and low scores based on different cutoff points. Sensitivities, specificities, and predictive powers of the "high" Chapman scores for SSPD diagnoses were then calculated. These were done because the Chapman Scales are often used to identify individuals with schizophrenia-related personality disorders on the basis of scores that exceed arbitrary cutoff points. The results suggest that the Chapman Scales (other than the Physical Anhedonia Scale) and DSM-III-R criteria identified mostly the same subjects, when only nonfamilial subjects were considered (with sensitivities and specificities of about 0.70). However, the overlap between these two constructs was poor when only schizophrenia spectrum subjects recruited from the family members of schizophrenic patients were considered.

Auditory evoked potentials in borderline personality disorder

Borderline personality disorder is an increasingly recognized condition and frequent management problem in psychiatric and nonpsychiatric practice. Paroxysmal changes in affect and behavior, high incidence of soft neurologic signs and frequent EEG alterations, and evidence of clinical response to antiepileptic drugs have suggested cerebral dysfunction, particularly involving the limbic system or reticular activating system. We recorded early latency brainstem auditory evoked potentials (BAEPs) and long-latency auditory event-related potentials (ERPs) in 20 patients fulfilling DSM-III-R criteria for this disorder. BAEPs were recorded from Cz to ipsilateral and contralateral ear reference, with rarefaction clicks presented at 11.1 per second and 70 dB SL. Two thousand averages were recorded and replicated for each ear, with filter band pass of 150-3000 Hz and 10 ms analysis time. ERPs utilized binaural stimulation with 1000 and 3000 Hz tones in an 80:20 ratio, with interstimulus interval 1.1 second, analysis time 1000 ms, and filter band pass 1-100 Hz. Two hundred averages were recorded and replicated from Cz with linked ear reference. No differences were evident in I-III, III-V, and I-V interpeak latencies between borderline patients and age-matched neurologically and audiologically normal controls. N1, P2, and N2 components of the AEPs were longer in latency and lower in amplitude in borderline patients, while P3 latency was longer and amplitude was attenuated in borderline patients as compared to controls. These findings may suggest differences from normals in attention maintenance and in limbic system function.

Magnetic resonance imaging of severely disturbed children--a preliminary study

This study investigates the relationship between brain pathology and psychiatric disturbance in 37 psychiatric inpatients between 5 and 14 years of age referred for magnetic resonance imaging (MRI). Of 37 images, 13 were categorized as abnormal by neuroradiologists who were blind to the diagnoses of subjects. Three of six children with schizophrenia-related diagnoses had abnormal scans. In contrast, only one of 15 children with a primary disruptive behavior disorder diagnosis had an abnormal magnetic resonance image. A greater proportion of children with schizophrenia spectrum diagnoses had greater left than right frontal horns of the lateral ventricles than children with other diagnoses.

Auditory P300 does not differentiate borderline personality disorder from schizotypal personality disorder

The P300 response to an auditory two-tone discrimination task has previously been reported to have prolonged latency and reduced amplitude in schizophrenia and borderline personality disorder. In this study, P300 was recorded from 23 subjects with borderline personality disorder, 12 subjects fulfilling criteria for both borderline and schizotypal personality, and 11 subjects with schizotypal personality. The mean P300 latency was similar in each of these groups and was significantly longer than in 32 patients with neuroses and other personality disorders and 74 nonpatient controls. These findings suggest that borderline and schizotypal patients share a similar abnormality in auditory stimulus evaluation and question whether or not these disorders are separate.