Associations Between Past Alcohol,Cannabis, and Cocaine Use and Current Schizotypy Among First-Degree Relatives of Patients With Schizophrenia and Non-Psychiatric Controls

Associations between past use of alcohol, cannabis, and cocaine and various domains of schizotypy were examined in first-degree relatives of patients with schizophrenia and non-psychiatric controls. Substance use was operationalized in three ways: (1) having ever used the substance, (2) age at first use, and (3) past frequency/amount of use during three time periods in late adolescence/early adulthood. Schizotypy was assessed using the Schizotypal Personality Questionnaire (SPQ). Participants who had ever used cannabis had significantly higher cognitive-perceptual, interpersonal, and total schizotypy scores compared to those who had not. Younger age of alcohol use onset was associated with more schizotypy in adulthood, and younger age of first cannabis use was related to more interpersonal schizotypy. More frequent/heavier use of alcohol in the 25–29 age-range, and cannabis in early adulthood, were associated with more schizotypy. The use of addictive substances, particularly cannabis, is related to schizotypy in complex ways.

Communication disturbances, working memory, and emotion in people with elevated disorganized schizotypy

This study examined whether people with elevated disorganized schizotypy would differ from control participants on characteristics associated with disorganization symptoms in schizophrenia and also whether disorganized schizotypy was associated with problems processing emotion. People with disorganized schizotypy (n = 32) exhibited greater communication disturbances (CD) than control participants (n = 34) for emotionally negative topics but not for positive topics. In addition, the disorganized group exhibited poorer performance on a working memory task but not on a psychometrically matched verbal intelligence task. In addition, poor working memory was associated with increased CD for negative topics and, after controlling for group differences in working memory, group differences in CD were not significant. Moreover, the disorganized group exhibited greater emotional ambivalence and ambivalence was associated with increased CD in the disorganized group. These results suggest that people with disorganized schizotypy exhibit some similar characteristics to people with schizophrenia who have disorganization symptoms and that disorganized schizotypy is also associated with poor emotion processing.     

Cannabis and schizophrenia: results of a follow-up study

A total of 39 schizophrenic patients with a history of current cannabis abuse at index admission was compared with a control group of schizophrenics without substance abuse matched for age, gender, and year of admission. At follow-up after 68.7 ± 28.3 months, 27/ 39 cases and 26/39 controls could be investigated. 8/27 cases (30%) had continued cannabis abuse, 6/27 (22%) had become alcohol abusers. Only one patient of the control group had started abusing alcohol. Patients with previous cannabis abuse had significantly more rehospitalizations, tended to worse psychosocial functioning, and scored significantly higher on the psychopathological syndromes “thought disturbance” (BPRS) and “hostility” (AMDP). These results confirm the major impact of cannabis abuse on the long-term outcome of schizophrenic patients. Received: 16 December 1997 / Accepted: 19 November 1998     

Reduced Kamin blocking in non paranoid schizophrenia: associations with schizotypy

Kamin blocking (KB) is an attentional phenomenon whereby prior learning about a stimulus (A) retards learning about a new stimulus (B) when later presented in compound (AB) with the original stimulus A. KB has been shown to be reduced in patients with schizophrenia. Using Oades' KB paradigm it has been suggested that drug treatment may influence the expression of KB abnormalities in patients. It is therefore unclear whether Reduced KB are due to drug treatment or to the illness itself. One experimental approach that circumvents drug treatment confounds is to study schizotypal traits in healthy volunteers. In the present study we investigated KB using the Oades paradigm in 27 healthy volunteers and 21 schizophrenic patients. We additionally investigated the relationship between KB performance and measures of schizotypal traits and a number of factors relevant to the experience of schizophrenia using the O-LIFE questionnaire. Our results indicate first a clear negative relationship between general schizotypy and more specifically, Unusual experiences (UNEX) and cognitive disorganisation (COGDIS) and KB performance. This relationship was qualitatively and quantitatively similar in both healthy volunteers and schizophrenic patients. Second we have independently replicated reduced KB in non-paranoid patients and no change in KB in paranoid patients using the Oades KB task. This study also confirms that reduced KB in non-paranoid patients is confined to early test trials (3-4) while the negative relationships with schizotypy scales UNEX and COGDIS that we have found are also confined to these early test trials confirming the psychological relevance of this specificity.     

Cannabis use in young people: the risk for schizophrenia

Cannabis is one of the most commonly used illicit drugs, and despite the widely held belief that it is a safe drug, its long-term use has potentially harmful consequences. To date, the research on the impact of its use has largely been epidemiological in nature and has consistently found that cannabis use is associated with schizophrenia outcomes later in life, even after controlling for several confounding factors. While the majority of users can continue their use without adverse effects, it is clear from studies of psychosis that some individuals are more vulnerable to its effects than others. In addiction, evidence from both epidemiological and animal studies indicates that cannabis use during adolescence carries particular risk. Further studies are warranted given the increase in the concentration of the main active ingredient (Δ⁹-tetrahydrocannabinol) in street preparations of cannabis and a decreasing age of first-time exposure to cannabis.     

Comorbidity of schizotypy and psychopathy: Skin conductance to affective pictures

Prior research indicates a relationship between psychopathy and schizophrenia, elucidating a specific trajectory toward violence. Recent research has suggested that this relationship exists at the nonclinical trait level of schizotypy; however, this finding has not been examined objectively. To explore this relationship using both subjective and objective measures, 54 undergraduates (50% male; mean age 20.41) who endorsed a wide range of schizotypy on the Schizotypal Personality Questionnaire (SPQ) completed a laboratory-based protocol. Participants viewed 15 pictures (five neutral, five threatening, and five of others in distress) from the International Affective Pictures System while electrodermal activity was recorded. As expected, all participants exhibited increased skin conductance levels (SCL) to threat and distress pictures compared to neutral pictures; however, no difference in SCL was found between threat and distress pictures. A unique relationship between psychopathy and schizotypy was found (i.e., schizotypy was related to higher Self-Centered Impulsivity and lower Fearless Dominance); however, schizotypy was related to increased SCL in response to emotional and neutral pictures. Although results do not support autonomic hyporesponsiveness often found in clinical psychopathy, a positive relationship was found between schizotypy and self-reported physical aggression. Findings highlight the need to examine other trajectories of violence within the schizophrenia spectrum disorders.     

Emotional intelligence and social functioning in persons with schizotypy

The present study is the first to examine emotional intelligence in persons with schizotypy. Over 2100 undergraduates were screened for schizotypy with the Schizotypal Personality Questionnaire - Brief Version. Forty participants identified as persons with high schizotypy and 56 participants identified as persons with low schizotypy completed assessments of emotional intelligence (Mayer-Salovey-Caruso Emotional Intelligence Test), social functioning (Social Adjustment Scale - Self Report), verbal episodic (secondary) memory (California Verbal Learning Test), and executive functioning (Wisconsin Card Sorting Test). Persons high in schizotypy were impaired in overall emotional intelligence and two aspects of emotional intelligence, the ability to perceive emotions and the ability to manage emotions. Persons high in schizotypy were also impaired in three aspects of social functioning: peer relationships, family relationships, and academic functioning. Group differences in verbal episodic (secondary) memory and executive functioning were not observed. For persons with high schizotypy, overall emotional intelligence and two aspects of emotional intelligence, the ability to perceive emotions and the ability to manage emotions, were associated with peer relationship functioning. Overall emotional intelligence was associated with verbal episodic (secondary) memory, but not executive functioning, in persons with high schizotypy. The current findings suggest that emotional intelligence is impaired in persons with schizotypy and that these impairments affect their social functioning.     

Birth characteristics and schizotypy: evidence of a potential "second hit"

Schizophrenia is associated with a modest increase in winter births as well as increased odds of being born in more densely populated and midrange latitude regions. It is unclear the degree to which these findings hold for individuals with schizotypy, defined in terms of the personality organization that is a potential precursor to schizophrenia-spectrum disorders. This issue is important for understanding whether birth factors contribute to general schizophrenia vulnerability or whether they reflect a secondary “hit” that increases the likelihood of psychosis onset in vulnerable individuals. The present project examined season of birth, birthplace population and birth location in a large group of young adults from the southeastern United States. Individuals with extreme schizotypy scores did not differ from those without schizotypy in season of birth, birthplace latitude or population. However, 60% of individuals within the schizotypy group who reported a diagnosis of schizophrenia or prior hospitalization were born during winter months; a dramatic difference from other individuals within the schizotypy group. We also found that individuals with negative/schizoid traits showed a birthplace population less than half that of other individuals with schizotypy. Season of birth appears to be a “second hit” that is related to expression of psychopathology onset in vulnerable individuals. This finding, and the unexpected inverse relationship between birthplace population and negative/schizoid traits, is discussed.     

Ignoring irrelevant stimuli in latent inhibition and Stroop paradigms: The effects of schizotypy and gender

Latent inhibition (LI), poor evidence of learning following preexposure to a task-irrelevant stimulus, reflects the ability to ignore inconsequential events. Stroop interference represents a failure to inhibit processing of a task-irrelevant word when it is incongruent with the required naming of the word's print color. The apparent commonality between the two effects is in contradiction to the literature, which indicates that LI is affected by schizotypy and schizophrenia, and perhaps gender, while Stroop interference generated by the trial-to-trial procedure is unaltered by those variables. In the present experiment, low schizotypal healthy males, but not females, exhibited LI. The same groups did not differ on Stroop interference. The results are discussed in terms of different processing requirements for task-irrelevant stimuli that are an integral part of the task-relevant target stimulus (as in Stroop) or separated from it in space (as in LI).     

The cross-cultural nature of the relationship between schizotypy and mixed-handedness

Positive schizotypy is associated with non-right-handedness, which includes left- and mixed-handedness. However, because the underlying mechanisms might be different, it is important to examine whether both left- and mixed-handedness are associated with a high incidence of schizotypy. During 2009–2010, we used both the Perceptual Aberration Scale and Schizotypal Personality Questionnaire to assess 1315 undergraduate students in Taiwan for schizotypy and the Annett handedness questionnaire to assess handedness. Among the three-way classifications based on Annett's grouping, the fully left-handed group appeared to have the lowest score of positive schizotypy; next was the fully right-handed group and then the mixed-handed. Among the three-way classifications driven from cluster analysis, mixed-handers showed highest score of positive schizotypy. When handedness was treated continuously, both direction (e.g., Hand Preference Index) and consistency (e.g., Either hand use score) indicators were significantly correlated with schizotypy. The results of regression analyses showed that the quadratic handedness measure were negatively associated with schizotypy. The results remained similar after correcting for social pressure on left-handedness. In conclusion, the relationship between schizotypy and mixed-handedness appears to be cross-cultural. The dichotomous classification of handedness, right- vs. non-right-handedness, appears to be insufficient. Additional studies on the distinct mechanisms of mixed- and left-handedness are warranted.     

Preattentional processes and disorganization in schizophrenia: Influence of a 6-week risperidone treatment

Introduction

Visual orientation and attention are impaired in schizophrenia. Engagement and disengagement of attention and the ability to prompt responses to a stimulus in patients before and after six weeks of risperidone were compared to controls.

Methods

Ten unmedicated (nine naïve) schizophrenic patients, and eleven controls performed 1) A visual orienting task, the Cued Target Detection task (CTD), with the detection of a visual stimulus in valid, invalid, no cue and double cue trials, two conditions for fixation offset for a modulation of visual fixation: Gap: 200 ms before target; No Gap: simultaneous with target, 2) Choice Reaction Time (CRT 0.5 and 2 s delays).

Results

At baseline, patients showed longer RT than controls in CRT, but not in CTD, with in CTD, no facilitation of RT with the gap procedure. The alertness index was almost null in CTD-Gap and comparable to controls in CTD-No Gap. Efficiency to detect attended stimuli (CTD-No Gap) and warning effect (CRT 0.5 s) were negatively correlated to disorganization. After treatment, readiness to act in CRT had decreased. In CTD-No Gap, change in PANSS disorganization was correlated to an increased validity index, change in negative sub-score was correlated to decreased attention cost.

Conclusion

Untreated patients displayed a deficit of Gap effect and a slowing in sustained attention. Disorganization interfered with warning and visual detection. After treatment, its improvement and negative symptoms improvement were associated with better visual detection. These alterations in visual orienting provide new evidence for an oculomotor dysregulation of attentional engagement in schizophrenia.     

Olanzapine vs. risperidone in patients with first-episode schizophrenia and a lifetime history of cannabis use disorders: 16-week clinical and substance use outcomes

The purpose of this study is to compare the efficacy of olanzapine and risperidone for the acute treatment of first-episode schizophrenia patients with cannabis use disorders. This secondary analysis of a previously published study included 49 first-episode patients with a diagnosis of schizophrenia, schizophreniform disorder, or schizoaffective disorder and a co-occurring lifetime diagnosis of cannabis use disorders randomly assigned to treatment with either olanzapine (n = 28) or risperidone (n = 21) for 16 weeks. The olanzapine group did not differ significantly from the risperidone group for initial response rates of positive symptoms, and rates of cannabis use or alcohol use during the study. Positive symptoms and the Scale for Assessment of Negative Symptoms (SANS) global asociality-anhedonia scores improved over time but did not differ between study medications. In both groups, cannabis use during the study was higher in patients who used cannabis within three months of the admission. Thus, our results suggest that olanzapine and risperidone had a similar initial efficacy on psychotic symptoms and substance use in first-episode patients with co-occurring cannabis use disorders. If clinicians are choosing between olanzapine versus risperidone treatment for this population, their decision should be based upon factors other than symptom response and short-term substance misuse.     

Semantic associations, lateralized frontal function, and context maintenance in schizotypy

Symptom heterogeneity within conventional diagnostic groups is fostering a growing focus on narrower symptom profiles to identify psychological and biological mechanisms in psychopathology. Positive symptoms of schizophrenia are associated with context maintenance deficits, which in turn have been linked to frontal-lobe function. Frontal- and temporal-lobe brain dysfunction is also well documented in schizophrenia. The present study (N=36) examined how context and memory deficits are associated with subclinical symptoms in schizotypy by investigating the relationship between symptom reports, neuropsychological performance, and several facets of recognition memory. Context maintenance was probed via lures suggested by presented verbal material. Frontal brain function and positive symptom schizotypy predicted accuracy for lures, whereas posterior brain function and low positive affect predicted accuracy for distracters. This pattern of findings establishes continuity in disruption of context maintenance in clinical and subclinical populations.     

Apophenia, theory of mind and schizotypy: perceiving meaning and intentionality in randomness

Impaired ability to correctly infer others' mental states (‘Theory of Mind’ - ToM) and the tendency to perceive meaning in unrelated events (‘apophenia’) have been implicated in vulnerability to schizophrenia. Sixty-three healthy participants completed three experimental tasks that provided indices of ToM and apophenia. The first task (Contingency) required participants to rate the strength of relationship between the movements of two shapes; in some conditions the movements were unrelated, in others the movement of one shape was contingent on that of the other. In the second task (Stories), participants answered questions on short stories with ‘random’, ‘physical’ or ‘ToM’ themes. The third task (Triangles) required participants to view and then describe the movement of triangles on a computer screen in ‘random’, ‘physical’ and ‘ToM’ conditions. Participants completed questionnaire measures of psychosis-proneness (the Schizotypal Personality Scale - STA) and delusional thinking style (Peters et al. Delusions Inventory - PDI-21). Little evidence was found on any of the tasks for an association between a specific deficit in ToM accuracy and any aspect of psychosis-proneness. On the Triangles task, schizotypal and delusion-prone participants spontaneously reported perceiving a greater number of associations in the random condition (apophenia). On both the Triangles and Contingency tasks, over-mentalizing was found to be associated with delusional thinking but not with general schizotypy. We speculate that over-mentalizing may be underpinned by a hyper-associative cognitive style, linked to an exaggeration of the normal human tendency to attribute mental states, rather than to dysfunction in the assessment of causality. Perceiving meaning in randomness and, more particularly, attributing mental states where none are indicated, may be important factors in the formation of paranormal and delusional beliefs.     

Metacognition in schizophrenia: Correlates and stability of deficits in theory of mind and self-reflectivity

Research suggests that many with schizophrenia experience a range of deficits in metacognition including difficulties recognizing the emotions and intentions of others as well as reflecting upon and questioning their own thinking. Unclear, however, is the extent to which these deficits are stable over time, how closely related they are to one another and whether their associations with core aspects of the disorder such as disorganization symptoms are stable over time. To explore this issue, we administered three assessments of Theory of Mind (ToM), the Beck Cognitive Insight Scale (BCIS), and the Positive and Negative Syndrome Scale at baseline and 6 months to 36 participants with schizophrenia. Correlations revealed the ToM and BCIS scores were stable across the two test administrations and that the ToM tests were closely linked to each other but not to the BCIS. Poorer baseline performance on the ToM tests and the Self-Certainty scale of the BCIS were linked to greater cognitive symptoms at baseline and follow-up, while greater Self-Reflectivity on the BCIS was linked to greater levels of emotional distress at both baseline and 6-month follow-up. Results are consistent with assertions that deficits in metacognition are a stable feature of schizophrenia.