Deeper into schizotypy and motor performance: Investigating the nature of motor control in a non-psychiatric sample

Online speech assessment of the psychotic spectrum: Exploring the relationship between overlapping acoustic markers of schizotypy, depression and anxiety

BACKGROUND

Remote assessment of acoustic alterations in speech holds promise to increase scalability and validity in research across the psychosis spectrum. A feasible first step in establishing a procedure for online assessments is to assess acoustic alterations in psychometric schizotypy. However, to date, the complex relationship between alterations in speech related to schizotypy and those related to comorbid conditions such as symptoms of depression and anxiety has not been investigated. This study tested whether (1) depression, generalized anxiety and high psychometric schizotypy have similar voice characteristics, (2) which acoustic markers of online collected speech are the strongest predictors of psychometric schizotypy, (3) whether including generalized anxiety and depression symptoms in the model can improve the prediction of schizotypy.

METHODS

We collected cross-sectional, online-recorded speech data from 441 participants, assessing demographics, symptoms of depression, generalized anxiety and psychometric schizotypy.

RESULTS

Speech samples collected online could predict psychometric schizotypy, depression, and anxiety symptoms with weak to moderate predictive power, and with moderate and good predictive power when basic demographic variables were added to the models. Most influential features of these models largely overlapped. The predictive power of speech marker-based models of schizotypy significantly improved after including symptom scores of depression and generalized anxiety in the models (from R2 = 0.296 to R2 = 0. 436).

CONCLUSIONS

Acoustic features of online collected speech are predictive of psychometric schizotypy as well as generalized anxiety and depression symptoms. The acoustic characteristics of schizotypy, depression and anxiety symptoms significantly overlap. Speech models that are designed to predict schizotypy or symptoms of the schizophrenia spectrum might therefore benefit from controlling for symptoms of depression and anxiety.

Why iPlay: The Relationships of Autistic and Schizotypal Traits With Patterns of Video Game Use

Video games are popular and ubiquitous aspects of human culture, but their relationships to psychological and neurophysiological traits have yet to be analyzed in social-evolutionary frameworks. We examined the relationships of video game usage, motivations, and preferences with autistic and schizotypal traits and two aspects of neurophysiology, reaction time and targeting time. Participants completed the Autism Quotient, Schizotypal Personality Questionnaire, a Video Game Usage Questionnaire, and two neurophysiological tasks. We tested in particular the hypotheses, motivated by theory and previous work, that: (1) participants with higher autism scores would play video games more, and participants with higher schizotypy scores would play video games less; and (2) autism and positive schizotypy would be associated with opposite patterns of video game use, preferences and motivations. Females, but not males, with higher autism scores played more video games, and exhibited evidence of relatively male-typical video game genre preferences and motivations. By contrast, positive schizotypy was associated with reduced video game use in both genders, for several measures of game use frequency. In line with previous findings, males played video game more than females did overall, preferred action video games, and exhibited faster reaction and targeting times. Females preferred Puzzle and Social Simulation games. Faster reaction and targeting times were associated with gaming motives related to skill development and building behavior. These findings show that gaming use and patterns reflect aspects of psychology, and gender, related to social cognition and imagination, as well as aspects of neurophysiology. More generally, the results suggest that video game use is notably affected by levels of autistic and schizotypal traits, and that video games may provide an evolutionarily novel medium for imaginative play in which immersive play experiences can be decoupled from social interaction.

The association of striatal volume and positive schizotypy in healthy subjects: intelligence as a moderating factor

BACKGROUND

Schizotypy, a putative schizophrenia endophenotype, has been associated with brain-structural variations partly overlapping with those in psychotic disorders. Variations in precuneus structure have been repeatedly reported, whereas the involvement of fronto-striatal networks - as in schizophrenia - is less clear. While shared genetic architecture is thought to increase vulnerability to environmental insults, beneficial factors like general intelligence might buffer their effect.

METHODS

To further investigate the role of fronto-striatal networks in schizotypy, we examined the relationship of voxel- and surface-based brain morphometry and a measure of schizotypal traits (Schizotypal Personality Questionnaire, with subscores Cognitive-Perceptual, Interpersonal, Disorganised) in 115 healthy participants [54 female, mean age (s.d.) = 27.57(8.02)]. We tested intelligence (MWT-B) as a potential moderator.

RESULTS

We found a positive association of SPQ Cognitive-Perceptual with putamen volume (p = 0.040, FWE peak level-corrected), moderated by intelligence: with increasing IQ, the correlation of SPQ Cognitive-Perceptual and striatal volume decreased (p = 0.022). SPQ Disorganised was positively correlated with precentral volume (p = 0.013, FWE peak level-corrected). In an exploratory analysis (p < 0.001, uncorrected), SPQ total score was positively associated with gyrification in the precuneus and postcentral gyrus, and SPQ Disorganised was negatively associated with gyrification in the inferior frontal gyrus.

CONCLUSIONS

Our findings support the role of fronto-striatal networks for schizotypal features in healthy individuals, and suggest that these are influenced by buffering factors like intelligence. We conclude that protective factors, like general cognitive capacity, might attenuate the psychosis risk associated with schizotypy. These results endorse the idea of a continuous nature of schizotypy, mirroring similar findings in schizophrenia.

Schizotypy and individual differences in peripersonal space plasticity

The space surrounding our body, defined as peripersonal space (PPS), is dynamically shaped by our motor experiences. For instance, PPS extends after using a tool to reach far objects. Several studies have demonstrated how PPS size varies across people, depending on different individual characteristics, including schizotypy. Coherently, narrower PPS boundaries have been reported among high schizotypal individuals and schizophrenia patients. However, little is known about the relationship between PPS plasticity and personality traits like schizotypy. To this purpose, the present study has investigated the individual PPS plasticity, after two different motor trainings, along the schizotypal continuum. Specifically, PPS plasticity was tested after using a tool (Experiment 1) and after the mere observation of another person using the same tool (Experiment 2). Indeed, previous evidence has shown that tool-use observation influences visual distance judgments, extending the representation of PPS. To date, however, there is no study investigating whether observation of tools action could also affect multisensory PPS tasks. Experiment 1 has shown that PPS boundaries extended after using the tool; on the other hand, Experiment 2 has revealed the absence of PPS expansion. Moreover, greater PPS expansion emerged in the relatively-low schizotypal group than in the relatively-high one, regardless of the type of motor training performed. The absence of PPS modulation after the observation task is discussed in relation to recent findings showing that intentional action and/or the goal of the action represent potentially crucial elements to trigger PPS plasticity. Finally, these new results extend previous evidence underlining a potential general functional alteration of PPS with the increase of schizotypal level.

Postural Sway Abnormalities in Schizotypal Personality Disorder

Motor abnormalities are among the most robust findings in schizophrenia, and increasing evidence suggests they are a core feature of the disorder. Postural sway during balance tasks is a highly sensitive probe of sensorimotor systems including the cerebellum, basal ganglia, and motor cortices. Postural sway deficits are present in schizophrenia as well as groups at high risk for psychosis, suggesting altered postural control may be sensitive to the pathophysiological processes associated with risk and expression of schizophrenia spectrum disorders. This study examined postural sway performance in schizotypal personality disorder (SPD). Individuals with SPD have attenuated psychotic symptoms and share genetic risk with schizophrenia but are usually free from antipsychotic medication and other illness confounds, making SPD useful for assessing candidate biomarkers. We measured postural sway using force plates in 27 individuals with SPD, 27 carefully matched controls, and 27 matched patients with schizophrenia. It was predicted that postural sway in the SPD group would fall intermediate to schizophrenia and controls. In all conditions (eyes open and closed, with feet together or apart), the SPD group swayed significantly more than the controls, as measured by path length and sway area. Moreover, the magnitude of the sway deficit was comparable in the SPD and schizophrenia groups. These findings suggest that postural sway measures may represent a sensorimotor biomarker of schizophrenia spectrum disorders.

Schizotypal traits and forearm motor control against self-other produced action in a bimanual unloading task

The present study investigated the relation between schizotypy and motor control against self- or other-produced action. We used an unloading task to focus on the timing component of anticipatory motor control. In the task, a weight was removed from a participants' hand by the participants themselves or by an experimenter (voluntary versus imposed unloading). Postural disturbance at the removal timing was measured as an index of predictive function in motor control. We hypothesized that the postural disturbance in the voluntary unloading would be positively related to schizotypal traits; however, the results did not support this theory. The results showed almost zero correlation between the schizotypy scores and the postural disturbance in the voluntary unloading condition. In contrast, the schizotypy scores positively correlated with the postural disturbance in the imposed unloading condition. These findings were replicated across two participant groups and two schizotypy scales. Further analyses on subscales of the schizotypy questionnaire found moderate levels of positive correlation between each subscale for Cognitive-Perceptual and Disorganization factors and the disturbance. Accordingly, the present study did not support the idea that non-pathological individuals with high schizotypal traits have deficits in prediction of self-produced actions, at least for a temporal domain. Instead, the results suggested that individuals with high schizotypal traits, particularly for the positive and disorganization symptoms, are not good at responding to others-produced actions. The schizophrenic symptoms were discussed in terms of the failure in the processes executed after calculating prediction of sensory consequences and dysfunction in internal models for "other people".

Structural alterations of the pyramidal pathway in schizoid and schizotypal cluster A personality disorders

AIM

Schizoid (ScPD) and Schizotypal (SPD) personality disorders are rare and severe disorders. They are associated with high liability to schizophrenia and present an attenuated form of its negative symptoms, which are considered a putative endophenotype for schizophrenia. The trans-diagnostic study of negative symptoms in non-psychotic populations such as ScPD/SPD might provide useful markers of a negative-symptom domain; however, little is known about their neurobiological substrates. The aim of the study was to investigate differences in gray and white matter volumes in subjects with ScPD/SPD compared to a group of healthy controls.

METHODS

Structural magnetic resonance images were obtained from 20 never-psychotic subjects with ScPD/SPD and 28 healthy controls. Resulting values from clusters of differences were correlated in patients with relevant clinical variables (O-LIFE scale).

RESULTS

ScPD/SPD presented greater bilateral white matter volume compared to healthy controls in the superior part of the corona radiata, close to motor/premotor regions, which correlated with the O-LIFE subtest of cognitive disorganization. No differences were found in regional gray matter or global gray/white matter volumes.

CONCLUSION

Greater volumes in motor pathways might relate to cognitive symptoms and motor alterations commonly present in schizophrenia-related disorders. Given the established link between motor signs and psychosis, structural alterations in motor pathways are suggested as a putative biomarker of a negative-symptom domain in psychosis subject to further testing.