Category fluency in psychometric schizotypy: how altering emotional valence and cognitive load affects performance

Semantic Memory Impairment Across the Schizophrenia Continuum: A Meta-Analysis of Category Fluency Performance

Semantic memory (SM) impairments are a core feature of schizophrenia and are present along the psychosis continuum. It is, however, unclear whether the degree of SM impairments vary along this continuum and if demographic and clinical factors affect impairment severity. This study performed meta-analyses of category fluency task performance (a task commonly used to assess SM) in 4 groups along the schizophrenia continuum: high schizotypes (HSZT), first-degree relatives (FDR), recent-onset patients (≤2 y; ROP) and chronic patients (CSZ). Electronic databases were searched for relevant studies published up to October 2019 resulting in the inclusion of 48 articles. The main analyses assessed fluency productivity scores in 2978 schizophrenia spectrum disorder patients, 340 first-degree relatives of schizophrenia spectrum disorder patients, and 3204 healthy controls. Further analyses assessed errors, mean cluster size, and switching data that were available in the CSZ group only. Results revealed significant impairments in fluency productivity were present in the FDR, ROP, and CSZ groups relative to healthy controls, but not in HSZT. In the CSZ group, significant differences relative to healthy controls were also observed in non-perseverative errors, mean cluster size, and number of switches. The findings collectively suggest that SM deficits are present at each stage of the continuum and are exacerbated post-illness onset. They also support the centrality of SM impairments in schizophrenia and most elevated risk groups. Future studies with more diverse measures of SM function are needed to replicate and extend this research.

Resting frontal EEG asymmetry and schizotypal traits: a test-retest study

Introduction: Increase in right relative to left frontal electroencephalography (EEG) activity has been observed in patients with schizophrenia, both in cognitive tasks and during rest; and this lateralisation may be related to the severity of schizotypal traits. Methods: We used the Schizotypal Personality Questionnaire (SPQ) to assess schizotypal traits, and examined the correlation between these traits and resting EEG frontal asymmetry (left-right) in 52 college students, as well as the reliability of this correlation over a three-month interval. Results: A higher total score on the SPQ was correlated with reduced asymmetry in different frequency bands: gamma and beta2 frequency bands at baseline, and delta and alpha frequency bands three months later. Additionally, the reduced left relative to right frontal gamma and beta2 asymmetry was correlated with the participants' verbal fluency ability. However, this correlation was no longer statistically significant after the total SPQ score was controlled. Conclusions: These findings suggest that resting frontal EEG asymmetry is correlated with powers in different frequency bands, and may be an endophenotype for schizophrenia spectrum disorders.

Semantic Search in Psychosis: Modeling Local Exploitation and Global Exploration

Impairments in category verbal fluency task (VFT) performance have been widely documented in psychosis. These deficits may be due to disturbed “cognitive foraging” in semantic space, in terms of altered salience of cues that influence individuals to search locally within a subcategory of semantically related responses (“clustering”) or globally between subcategories (“switching”). To test this, we conducted a study in which individuals with schizophrenia (n = 21), schizotypal personality traits (n = 25), and healthy controls (n = 40) performed VFT with “animals” as the category. Distributional semantic model Word2Vec computed cosine-based similarities between words according to their statistical usage in a large text corpus. We then applied a validated foraging-based search model to these similarity values to obtain salience indices of frequency-based global search cues and similarity-based local cues. Analyses examined whether diagnosis predicted VFT performance, search strategies, cue salience, and the time taken to switch between vs search within clusters. Compared to control and schizotypal groups, individuals with schizophrenia produced fewer words, switched less, and exhibited higher global cue salience, indicating a selection of more common words when switching to new clusters. Global cue salience negatively associated with vocabulary ability in controls and processing speed in schizophrenia. Lastly, individuals with schizophrenia took a similar amount of time to switch to new clusters compared to control and schizotypal groups but took longer to transition between words within clusters. Findings of altered local exploitation and global exploration through semantic memory provide preliminary evidence of aberrant cognitive foraging in schizophrenia.

Social functioning in schizotypy: How affect influences social behavior in daily life

OBJECTIVE

Social deficits are already exhibited by people at risk for schizophrenia-spectrum disorders. Technological advances have made passive detection of social deficits possible at granular levels.

METHOD

In this real-world study, we tested if schizotypy status (high/low) predicted two types of social behavior: (1) being around other people; and (2) actively socializing with others. We also examined if schizotypy influences relationships between social behavior and affect using subjective and objective instruments.

RESULTS

Our findings revealed that socializing with others was significantly decreased in the high schizotypy group. Positive affect increased in social situations and predicted later social behavior in those low, but not high, in schizotypy.

CONCLUSION

Decreased social behavior in schizotypy may be explained, in part, by these individuals being less incentivized than their peers to pursue social situations. Future studies should test this explanation in larger samples exhibiting elevated positive, negative, and disorganized schizotypy traits.

Schizotypal personality and semantic functioning: Revisiting category fluency effects in a subclinical sample

Semantic disturbances have been proposed as a possible cause of formal thought disorder in schizophrenia. Fluency tasks, in which volunteers are asked to produce as many exemplars as they can for a given category during one minute, are usually applied to the assessment of semantic processing. However, studies associating fluency and proneness to psychosis have provided conflicting results so it is not clear whether these disturbances can be identified at subclinical stages. We conducted two experiments. In the first one, 71 volunteers completed written category fluency tasks with four semantic categories (animals, fruits, clothing and vehicles). In the second experiment, 77 new participants completed oral category and phonological fluency tasks (words starting with f, t, p and c). In both experiments, we assessed schizotypal personality and vocabulary size. Schizotypal traits were not reliably associated with either productivity or originality of the responses in any experiment. In contrast, vocabulary size significantly predicted the participants' scores in all the tasks. Along with results of other recent studies, our data cast doubt on the reliability of previous observations pointing out an association between schizotypy and lexical-semantic disturbances, at least in relation to productivity and originality in fluency tests.

A test of the cognitive model of negative symptoms: Associations between defeatist performance beliefs, self-efficacy beliefs, and negative symptoms in a non-clinical sample

The cognitive model of negative symptoms posits that defeatist performance beliefs-overgeneralized negative beliefs about one's ability to successfully perform tasks-contribute to the development and maintenance of negative symptoms. However, a conceptually similar construct, reduced generalized self-efficacy-diminished confidence in one's ability to effectively complete or respond to new or challenging tasks and situations-has also been linked to negative symptoms. To identify which beliefs might be most important to target to reduce negative symptoms, we examined: 1) the association between defeatist performance and self-efficacy beliefs and 2) which beliefs are more strongly associated with negative symptoms in a non-clinical sample of young adults (N = 941). Analyses revealed a significant, medium-sized correlation between defeatist performance and self-efficacy beliefs. Both beliefs types were significantly associated with negative symptoms, but defeatist performance beliefs were more strongly related to negative symptoms than self-efficacy beliefs. Defeatist performance and self-efficacy beliefs appear to be distinct yet overlapping constructs. Findings support the cognitive model and indicate that defeatist performance beliefs may have a greater role in the manifestation of negative symptoms than self-efficacy beliefs. Thus, defeatist performance beliefs may be a uniquely promising treatment target for reducing or preventing negative symptoms.

Executive function in patients with schizophrenia based on socio-occupational impairment: A cross-sectional study

BACKGROUND

Executive dysfunction deficit is the functionally most important cognitive deficit noted in schizophrenia. There is a dearth of Indian literature on the subject. The current study aimed at studying these executive functions in patients with schizophrenia in remission.

METHODOLOGY

Sixty outpatients with a diagnosis of schizophrenia as per international classification of diseases-10 criteria; in remission as measured by Positive and Negative Syndrome Scale scores were divided into two groups using the personal and social performance scale. The patients with and without socio-occupational impairment formed the two groups. All patients were administered the Wisconsin Card Sorting Test (WCST), Stroop test, Color Trails Test 1 and 2, Phonemic Fluency (Controlled Oral Word Association Test), and category fluency (animal names test) tests and the tower of London test to ascertain deficits in executive functions. The data obtained were subjected to statistical analysis.

RESULTS

The two groups were well matched. The group with socio-occupational impairment showed a lesser number of categories completed (P = 0.001), more perseverative errors (P = 0.001), and greater percentage of the same (P = 0.001) on the WCST. Statistically significant differences between both groups were observed for scores on phonemic fluency (P = 0.012) and category fluency (P = 0.049) tests as well as the Tower of London test (P = 0.021). They also showed differences on the Stroop test and Color Trail tests, but this was not statistically significant.

CONCLUSIONS

Performance on executive function tests is significantly correlated with functional outcome. It is important that future studies explore the role of these tests as a marker of socio-occupational impairment in schizophrenia.

Semantic coherence in psychometric schizotypy: An investigation using Latent Semantic Analysis

Technological advancements have led to the development of automated methods for assessing semantic coherence in psychiatric populations. Latent Semantic Analysis (LSA) is an automated method that has been used to quantify semantic coherence in schizophrenia-spectrum disorders. The current study examined whether: 1) Semantic coherence reductions extended to psychometrically-defined schizotypy and 2) Greater cognitive load further reduces semantic coherence. LSA was applied to responses generated during category fluency tasks in baseline and cognitive load conditions. Significant differences between schizotypy and non-schizotypy groups were not observed. Findings suggest that semantic coherence may be relatively preserved at this point on the schizophrenia-spectrum.

Additional support for the cognitive model of schizophrenia: evidence of elevated defeatist beliefs in schizotypy

OBJECTIVES

The cognitive model of poor functioning in schizophrenia posits that defeatist performance beliefs-overgeneralized negative beliefs about one's ability to perform tasks-develop prior to the onset of psychosis and contribute to the development and maintenance of negative symptoms and poor functioning. Although several studies with schizophrenia samples have provided support for the model, there is a paucity of research investigating these beliefs in individuals with schizotypy-those exhibiting traits reflecting a putative genetic liability for schizophrenia. This study had two aims: to examine whether defeatist performance beliefs (1) are elevated in schizotypy compared to controls and (2) are associated with decreased quality of life and working memory and increased negative but not positive schizotypy traits in the schizotypy group.

METHODS

Schizotypy (n=48) and control (n=53) groups completed measures of schizotypy traits, defeatist performance beliefs, quality of life, and working memory.

RESULTS

Analyses revealed that the schizotypy group reported significantly more defeatist performance beliefs than the control group. Within the schizotypy group, increased defeatist performance beliefs were significantly associated with greater negative schizotypy traits and lower quality of life. No significant associations were observed between defeatist performance beliefs and positive schizotypy traits and working memory.

CONCLUSIONS

Results generally support the theoretical validity of the cognitive model of poor functioning in schizophrenia and suggest that elevated defeatist performance beliefs may contribute to the manifestation of subclinical negative symptom traits and reduced quality of life among those with a latent vulnerability for schizophrenia.