Schizotypal disorder and schizophrenia: a profile analysis of neuropsychological functioning in Japanese patients

The relationship between cognitive reserve focused on leisure experiences and cognitive functions in bipolar patients

Bipolar disorder (BP) is characterized by cognitive decline. Individual differences exist in maintaining cognitive function due to daily physical activity and sleep. We examined the relationship between leisure experiences as proxies for cognitive reserve (CR) and cognitive function in patients with bipolar disorder after adjusting for daily physical activity and sleep. The CR of patients with BP (n = 24) and healthy study controls (HC) (n = 24) was assessed using premorbid IQ, years of education, and leisure activity history. Performance-based neuropsychological tests were performed to evaluate cognitive function. A self-reported scale was used to assess resilience. Physical activity and sleep were measured using an activity meter. Verbal fluency, story memory, and verbal memory were significantly positively correlated with the kinds of leisure experiences in patients with BP. A hierarchical regression analysis accounting for confounding factors showed that verbal fluency and memory were associated with the kinds of leisure experiences. Neither years of education nor resilience were significantly associated with neuropsychological scores. Various leisure experiences in patients with BP are associated with higher language-related cognitive functioning. Engaging in various leisure experiences may affect higher cognitive functions related to language.

Premorbid intellectual ability in schizophrenia influence family appraisal related to cognitive impairments: a cross-sectional study on cognitive impairment and family assessments

BACKGROUND

Patients with schizophrenia are unaware of their cognitive impairments. Misperception of cognitive impairment is an important factor associated with real-world functional outcomes in patients with schizophrenia. The patient's family member plays a crucial role in detecting patients' cognitive impairments when the patients are unaware of their own cognitive impairments. Previous studies have reported that not only the patient's subjective rating, but also the patient's family members' rating of their cognitive impairment may not be precise. However, it is unclear why family ratings are inaccurate, and which factors impact family ratings. This study investigated whether family ratings differed significantly from the patients' subjective ratings of the patients' cognitive impairments and sought to determine the reason for the differences between the family ratings and the patients' neurocognitive performances. We investigated the relationship between patients' subjective ratings, family ratings for patients' cognitive impairments, neuropsychological performance, and other aspects, including premorbid IQ and clinical symptoms.

METHOD

We evaluated 44 patients with schizophrenia for cognitive function using neuropsychological tests; in addition, both the patients and their families rated the patients' cognitive impairments through questionnaires. We used the Mann-Whitney U test to examine whether the family ratings differed significantly from the patients' self-reported ratings of their cognitive impairment. We conducted multiple regression analysis and structural equation modeling to determine why the patients' subjective ratings and the family ratings were not definitively associated with the patients' neurocognitive performances. We performed multiple regression analysis with a stepwise method with neurocognitive performance, premorbid IQ, positive symptoms, and negative symptoms as independent variables and family ratings of patients' cognitive impairments as dependent variables.

RESULTS

We found that the family ratings differed significantly from the patients' subjective self-reported ratings of their cognitive impairments. Our results showed that the premorbid IQ of patients is the strongest predictor of family ratings. Furthermore, among the neurocognitive domains, only the processing speed of patients was associated with family ratings.

CONCLUSIONS

We found that the family ratings were not consistent with the patients' subjective self-reported ratings and the family ratings were most affected by the patients' premorbid intellectual abilities. These results suggest that the families' current assessments of the patients' current cognitive impairments were affected by the patients' premorbid intellectual ability rather than the patients' current neurocognitive performance. Patients' processing speed predicted family ratings; however, family members' ratings were not related to verbal learning/memory, executive function, and language of patients. Therefore, our findings highlight that patients' family ratings may differ from patients' subjective ratings, results of performance-based neuropsychological tests, and clinician ratings.

Schizotypal traits and neuropsychological performance: The role of processing speed

BACKGROUND

Cognitive deficits, particularly in processing speed, are widely recognized as a critical feature of schizophrenia, and are also present across schizophrenia spectrum disorders. A number of important confounders, however, such as hospitalization effects and antipsychotic medication, have been shown to affect processing speed, causing debate as to the core cognitive deficits of schizophrenia. The study of individuals who are not clinically psychotic but have schizotypal traits allows investigation of cognitive deficits associated with both positive and negative schizotypy dimensions while excluding potential confounds.

METHODS

A population-based community sample of 242 healthy adult volunteers assessed using the Structured Interview of Schizotypy - Revised (SIS-R) scale, and a neuropsychological testing battery that included measures of verbal ability, visual and verbal memory, verbal fluency, working memory, executive functions and processing speed. Participants were classified in High or Low Positive Schizotypy (H-PST or L-PST), High or Low Paranoia-like traits (H-PAR or L-PAR) and High or Low Negative Schizotypy (H-NST or L-NST) groups, respectively.

RESULTS

Individuals with H-PST performed significantly (p < 0.05) worse than L-PST on measures of processing speed and executive functions. Processing speed deficits were also observed in individuals with H-PAR compared to L-PAR (p < 0.05). There were no statistically significant differences in neuropsychological performance between H-NST and L-NST on any measure.

CONCLUSIONS

In a population-based community sample, individuals with high positive schizotypal traits or paranoia-like traits show impairments in processing speed. Consistent with a dimensional view of psychosis, this supports the hypothesis that processing speed represents a core deficit of schizophrenia-like mental states.

Severe childhood trauma and clinical and neurocognitive features in schizotypal personality disorder

OBJECTIVE

Literature suggests that childhood trauma increases vulnerability for schizophrenia-spectrum disorders, including schizotypal personality disorder (SPD). Yet, it remains unexplored whether childhood trauma predicts symptom load and the level of neurocognitive functioning in SPD.

METHOD

We included 225 individuals with SPD and 127 healthy controls. Childhood trauma was evaluated using the Childhood Trauma Questionnaire, and schizotypal traits were assessed using the Schizotypal Personality Questionnaire. Standard neurocognitive assessments covered six cognitive domains.

RESULTS

All types of reported childhood trauma were significantly associated with SPD, in a linear fashion. Severe sexual abuse showed the greatest magnitude of association with higher cognitive-perceptual load (e.g., ideas of reference, odd belief or magical thinking); severe emotional neglect was associated with interpersonal scores (e.g., excessive social anxiety, constricted affect) within the SPD group. SPD individuals who reported severe trauma showed worse cognitive functioning (i.e., working memory, verbal/visual learning and memory, as well as verbal fluency).

CONCLUSIONS

Particular severe childhood trauma types were associated with higher cognitive-perceptual and interpersonal symptoms in SPD, along with worse cognitive functioning. These findings highlight the need for clinicians to enquire about childhood trauma in SPD patients, since unaddressed early adverse experiences may carry long-term negative consequences.

Schizotypy is associated with reduced mnemonic precision in visual working memory

BACKGROUND

Working memory (WM) maintains a limited amount of information over a short period of time at the service of other ongoing mental activities. Deficits in this function are often observed in schizophrenia spectrum disorders. The present study examined whether self-report schizotypy was associated with the qualitative, quantitative, or both aspects of visual WM and whether these impairments could be accounted for by sensory memory deficits and/or depressed mood in a group of non-clinical, medication-naïve participants.

METHOD

Visual WM and sensory memory were assessed in 164 medication-naïve college students using delayed and immediate color estimation tasks, respectively. Self-report measures of schizotypy and depressed mood were also collected.

RESULTS

Individuals with more schizotypal features retained less precise representations in visual WM, without a significant reduction in the number of retained WM representations (i.e., capacity). In contrast, there was no significant correlation between sensory memory precision and schizotypy, suggesting that schizotypy-related imprecision in visual WM was unlikely a result of imprecise sensory memory. Furthermore, opposite patterns of WM deficits were observed for depressed mood in that it was negatively associated with WM capacity, but not with WM precision.

CONCLUSION

Together, the present findings demonstrated dissociable WM deficits in schizotypy and depressed mood, providing strong evidence for unstable mental representations in schizotypy and reduced cognitive resource in depressed mood.

Neurocognitive Predictors of Response in Treatment Resistant Depression to Subcallosal Cingulate Gyrus Deep Brain Stimulation

Background: Deep brain stimulation (DBS) is a neurosurgical intervention with demonstrated effectiveness for treatment resistant depression (TRD), but longitudinal studies on the stability of cognitive parameters following treatment are limited. The objectives of this study are to (i) identify baseline cognitive predictors of treatment response to subcallosal cingulate gyrus (SCG) DBS for unipolar TRD and (ii) compare neurocognitive performance prior to and 12 months after DBS implantation.

Methods: Twenty unipolar TRD patients received SCG DBS for 12 months. A standardized neuropsychological battery was used to assess a range of neurocognitive abilities at baseline and after 12 months. Severity of depression was evaluated using the 17 item Hamilton Rating Scale for Depression.

Results: Finger Tap-Dominant Hand Test and total number of errors made on the Wisconsin Card Sorting Test predicted classification of patients as treatment responders or non-responders, and were independent of improvement in mood. Change in verbal fluency was the only neuropsychological test that correlated with change in mood from baseline to the follow up period. None of the neuropsychological measures displayed deterioration in cognitive functioning from baseline to repeat testing at 12 months.

Limitations: This was an open label study with a small sample size which limits predictive analysis. Practice effects of the neuropsychological testing could explain the improvement from baseline to follow up on some tasks. Replication using a larger sample of subjects who received neuropsychological testing before and at least 12 months after DBS surgery is required.

Conclusion: These preliminary results (i) suggest that psychomotor speed may be a useful baseline predictor of response to SCG DBS treatment and (ii) support previous suggestions that SCG DBS has no deleterious effects on cognition.

Neuropsychological Characteristics and Their Association with Higher-Level Functional Capacity in Parkinson's Disease

BACKGROUND/AIMS

Little is known about the relationship between cognitive functions and higher-level functional capacity (e.g. intellectual activity, social role, and social participation) in Parkinson's disease (PD). The purpose of this study was to clarify neuropsychological characteristics and their association with higher-level functional capacity in PD patients.

METHODS

Participants were 31 PD patients and 23 demographically matched healthy controls. Neuropsychological tests were conducted. One year later, a questionnaire survey evaluated higher-level functional capacity in daily living.

RESULTS

The PD group scored significantly lower than the control group in all cognitive domains, particularly executive function and processing. Executive function, processing speed, language, and memory were significantly correlated with higher-level functional capacity in PD patients. Stepwise regression showed that only executive function (Trail Making Test-B), together with disease severity (HY stage), predicted the higher-level functional capacity.

CONCLUSION

Our findings provide evidence of a relationship between executive function and higher-level functional capacity in patients with PD.

Oxytocin and social cognition in affective and psychotic disorders

Impairments in social cognition are now recognized as core illness features in psychotic and affective disorders. Despite the significant disability caused by social cognitive abnormalities, treatments for this symptom dimension are lacking. Here, we describe the evidence demonstrating abnormalities in social cognition in schizophrenia, major depressive disorder, and bipolar disorder, as well as the neurobiology of social cognition including the role of oxytocin. We then review clinical trials of oxytocin administration in psychotic and affective disorders and the impact of this agent on social cognition. To date, several studies have demonstrated that oxytocin may improve social cognition in schizophrenia; too few studies have been conducted in affective disorders to determine the effect of oxytocin on social cognition in these disorders. Future work is needed to clarify which aspects of social cognition may be improved with oxytocin treatment in psychotic and affective disorders.

Empathic accuracy and cognition in schizotypal personality disorder

Interpersonal dysfunction contributes to significant disability in the schizophrenia spectrum. Schizotypal Personality Disorder (SPD) is a schizophrenia-related personality demonstrating social cognitive impairment in the absence of frank psychosis. Past research indicates that cognitive dysfunction or schizotypy may account for social cognitive dysfunction in this population. We tested SPD subjects and healthy controls on the Empathic Accuracy (EA) paradigm and the Reading of the Mind in the Eyes Test (RMET), assessing the impact of EA on social support. We also explored whether EA differences could be explained by intelligence, working memory, trait empathy, or attachment avoidance. SPD subjects did not differ from controls in RMET, but demonstrated lower EA during negative valence videos, associated with lower social support. Dynamic, multimodal EA paradigms may be more effective at capturing interpersonal dysfunction than static image tasks such as RMET. Schizotypal severity, trait empathy, and cognitive dysfunction did not account for empathic dysfunction in SPD, although attachment avoidance is related to empathic differences. Empathic dysfunction for negative affect contributes to decreased social support in the schizophrenia spectrum. Future research may shed further light on potential links between attachment avoidance, empathic dysfunction, and social support.

Neuropsychological impairments in schizophrenia and psychotic bipolar disorder: findings from the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) study

OBJECTIVE

Familial neuropsychological deficits are well established in schizophrenia but remain less well characterized in other psychotic disorders. This study from the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) consortium 1) compares cognitive impairment in schizophrenia and bipolar disorder with psychosis, 2) tests a continuum model of cognitive dysfunction in psychotic disorders, 3) reports familiality of cognitive impairments across psychotic disorders, and 4) evaluates cognitive impairment among nonpsychotic relatives with and without cluster A personality traits.

METHOD

Participants included probands with schizophrenia (N=293), psychotic bipolar disorder (N=227), schizoaffective disorder (manic, N=110; depressed, N=55), their first-degree relatives (N=316, N=259, N=133, and N=64, respectively), and healthy comparison subjects (N=295). All participants completed the Brief Assessment of Cognition in Schizophrenia (BACS) neuropsychological battery.

RESULTS

Cognitive impairments among psychotic probands, compared to healthy comparison subjects, were progressively greater from bipolar disorder (z=-0.77) to schizoaffective disorder (manic z=-1.08; depressed z=-1.25) to schizophrenia (z=-1.42). Profiles across subtests of the BACS were similar across disorders. Familiality of deficits was significant and comparable in schizophrenia and bipolar disorder. Of particular interest were similar levels of neuropsychological deficits in relatives with elevated cluster A personality traits across proband diagnoses. Nonpsychotic relatives of schizophrenia probands without these personality traits exhibited significant cognitive impairments, while relatives of bipolar probands did not.

CONCLUSIONS

Robust cognitive deficits are present and familial in schizophrenia and psychotic bipolar disorder. Severity of cognitive impairments across psychotic disorders was consistent with a continuum model, in which more prominent affective features and less enduring psychosis were associated with less cognitive impairment. Cognitive dysfunction in first-degree relatives is more closely related to psychosis-spectrum personality disorder traits in psychotic bipolar disorder than in schizophrenia.

Schizotypal personality disorder

Early phenomenological descriptions of schizophrenia have acknowledged the existence of milder schizophrenia spectrum disorders characterized by the presence of attenuated symptoms typically present in chronic schizophrenia. The investigation of the schizophrenia spectrum disorders offers an opportunity to elucidate the pathophysiological mechanisms giving rise to schizophrenia. Differences and similarities between subjects with schizotypal personality disorder (SPD), the prototypical schizophrenia personality disorder, and chronic schizophrenia have been investigated with genetic, neurochemical, imaging, and pharmacological techniques. Patients with SPD and the more severely ill patients with chronic schizophrenia share cognitive, social, and attentional deficits hypothesized to result from common neurodevelopmentally based cortical temporal and prefrontal pathology. However, these deficits are milder in SPD patients due to their capacity to recruit other related brain regions to compensate for dysfunctional areas. Individuals with SPD are also less vulnerable to psychosis due to the presence of protective factors mitigating subcortical DA hyperactivity. Given the documented close relationship to other schizophrenic disorders, SPD will be included in the psychosis section of DSM-5 as a schizophrenia spectrum disorder as well as in the personality disorder section.

Cognitive and prepulse inhibition deficits in psychometrically high schizotypal subjects in the general population: relevance to schizophrenia research

Schizophrenia and schizotypal personality disorder share common clinical profiles, neurobiological and genetic substrates along with Prepulse Inhibition and cognitive deficits; among those, executive, attention, and memory dysfunctions are more consistent. Schizotypy is considered to be a non-specific "psychosis-proneness," and understanding the relationship between schizotypal traits and cognitive function in the general population is a promising approach for endophenotypic research in schizophrenia spectrum disorders. In this review, findings for executive function, attention, memory, and Prepulse Inhibition impairments in psychometrically defined schizotypal subjects have been summarized and compared to schizophrenia patients and their unaffected first-degree relatives. Cognitive flexibility, sustained attention, working memory, and Prepulse Inhibition impairments were consistently reported in high schizotypal subjects in accordance to schizophrenia patients. Genetic studies assessing the effects of various candidate gene polymorphisms in schizotypal traits and cognitive function are promising, further supporting a polygenic mode of inheritance. The implications of the findings, methodological issues, and suggestions for future research are discussed.

Correlation of individual differences in schizotypal personality traits with amphetamine-induced dopamine release in striatal and extrastriatal brain regions

OBJECTIVE

Schizotypal personality traits are associated with schizophrenia spectrum disorders, and individuals with schizophrenia spectrum disorders demonstrate increased dopamine transmission in the striatum. The authors sought to determine whether individual differences in normal variation in schizotypal traits are correlated with dopamine transmission in the striatum and in extrastriatal brain regions.

METHOD

Sixty-three healthy volunteers with no history of psychiatric illness completed the Schizotypal Personality Questionnaire and underwent positron emission tomography imaging with [(18)F]fallypride at baseline and after administration of oral d-amphetamine (0.43 mg/kg). Dopamine release, quantified by subtracting each participant's d-amphetamine scan from his or her baseline scan, was correlated with Schizotypal Personality Questionnaire total and factor scores using region-of-interest and voxel-wise analyses.

RESULTS

Dopamine release in the striatum was positively correlated with overall schizotypal traits. The association was especially robust in the associative subdivision of the striatum. Voxel-wise analyses identified additional correlations between dopamine release and schizotypal traits in the left middle frontal gyrus and left supramarginal gyrus. Exploratory analyses of Schizotypal Personality Questionnaire factor scores revealed correlations between dopamine release and disorganized schizotypal traits in the striatum, thalamus, medial prefrontal cortex, temporal lobe, insula, and inferior frontal cortex.

CONCLUSIONS

The association between dopamine signaling and psychosis phenotypes extends to individual differences in normal variation in schizotypal traits and involves dopamine transmission in both striatal and extrastriatal brain regions. Amphetamine-induced dopamine release may be a useful endophenotype for investigating the genetic basis of schizophrenia spectrum disorders.

The relationship between prefrontal brain volume and characteristics of memory strategy in schizophrenia spectrum disorders

The present study investigated the relationship between memory strategy use and prefrontal gray/white matter volumes of healthy control subjects, patients with schizophrenia or schizotypal disorder. Gray/white matter volumes were measured for the superior, middle, inferior, ventral medial and orbital prefrontal regions, using high-resolution magnetic resonance (MR) images that were acquired from 35 patients with schizophrenia, 25 patients with schizotypal disorder and 19 healthy subjects. Participants were also administered the Japanese Verbal Learning Test (JVLT). In control subjects, larger left inferior frontal and straight gyrus's gray matter volumes were associated with higher semantic clustering rates on the JVLT, and smaller left inferior frontal gray matter volumes were associated with higher serial clustering ratio. In schizophrenic patients, smaller left orbitofrontal gray matter volumes were associated with lower semantic clustering rates on the JVLT. In schizotypal patients, smaller left inferior frontal white matter volume was associated with smaller serial clustering rates and larger semantic clustering rate. These findings suggest that semantic organization in schizophrenic patients might depend on mobilization of a memory strategy that is mediated by orbitofrontal cortex functioning. Failure to use a semantic organization strategy might be related to reduced volume in the inferior frontal gyrus. The findings for schizotypal patients suggest a compensation mechanism to remember the words using a serial processing strategy is at work when the inferior frontal gyrus cannot mediate semantic processing.

Cognitive functioning related to quality of life in schizophrenia

The present study compared the cognitive function of patients with schizophrenia to that of healthy subjects, and investigated the relationships between cognitive function and quality of life (QOL). Participants consisted of 53 patients meeting DSM-IV criteria for schizophrenia and 31 normal controls. All participants completed a neuropsychological test battery assessing executive function, verbal memory, and social knowledge. QOL was rated using the Schizophrenia Quality of Life Scale. Patients with schizophrenia showed lower performance across various cognitive measures of memory, including the Sentence Memory Test, the Verbal Learning Test, and the Script Test, as well as the Rule Shift Cards Test of executive function. Multiple regression analyses were used to evaluate the neuropsychological measures and clinical symptoms to predict QOL. The QOL total score, the social initiative score or the empathy score were significantly predicted by the Script or/and the Sentence Memory. Neuropsychological functioning was unrelated to most QOL scores in the presence of clinical symptoms, while ability of empathy in the QOL was predicted by performance of the Sentence Memory Test. These results demonstrated patients with schizophrenia have deficits in executive function, memory and learning, and social knowledge, and that social knowledge and memory are related to QOL. Thus, in patients with schizophrenia, deficits in social knowledge appear to be associated with current QOL in general, and specifically with the capacity for empathy and social initiative.