BDNF Val66Met and spontaneous dyskinesias in non-clinical psychosis

Facial and upper-limb movement abnormalities in individuals with psychotic-like experiences: a motion analysis study

Slow movements and irregular muscle contraction have been reported separately in different studies targeting individuals with psychotic-like experiences (PLEs). To date, it remains unknown whether these two movement abnormalities, possibly associated with hypo- and hyper-dopaminergia, respectively, co-existed in one sample with PLEs and interrelated in the early stage of psychotic progression. Therefore, this study was to examine if facial and upper-limb slow movements and irregular muscle contraction co-existed in individuals with PLEs, interrelated, and were associated with PLEs. A total of 26 individuals with PLEs, who were identified using the 16-item Prodromal Questionnaire, and 26 age- and gender-matched healthy controls received the facial and upper-limb movement measurement. A motion capture system was used to record the movement procedure and thus calculate kinematic variables that represented severity of slow movements and irregular muscle contraction. Results showed that facial and upper-limb slow movements and facial irregular muscle contraction existed in individuals with PLEs. For the total sample, slower facial movements were associated with less regular facial muscle contraction; slower upper-limb movements were associated with less regular upper-limb muscle contraction. Slower and less regular facial and upper-limb movements were associated with more severe PLEs. Compensatory changes in dopaminergic neural pathways in response to elevated dopamine might explain connection between slow movements and irregular muscle contraction. Because of the ability to detect facial and upper-limb movement abnormalities objectively and sensitively, motion analysis has great applicability to sensorimotor studies for people in the psychosis continuum.

Community Psychosis Risk Screening: An Instrument Development Investigation

Schizophrenia and other psychotic disorders are serious psychiatric disorders that are associated with substantial societal, family, and individual costs/distress. Evidence suggests that early intervention can improve prognostic outcomes; therefore, it is essential to accurately identify those at risk for psychosis before full psychotic symptoms emerge. The purpose of our study is to develop a brief, valid screening questionnaire to identify individuals at risk for psychosis in non-clinical populations across 3 large, community catchment areas with diverse populations. This is a needed study, as the current screening tools for at-risk psychotic populations in the US have been validated only in clinical and/or treatment seeking samples, which are not likely to generalize beyond these specialized settings. The specific aims are as follows: (1) to determine norms and prevalence rates of attenuated positive psychotic symptoms across 3 diverse, community catchment areas and (2) to develop a screening questionnaire, inclusive of both symptom-based and risk factor-based questions. Our study will develop an essential screening tool that will identify which individuals have the greatest need of follow-up with structured interviews in both research and clinical settings. Our study has the potential for major contributions to the early detection and prevention of psychotic disorders.

Longitudinal Assessment and Functional Neuroimaging of Movement Variability Reveal Novel Insights Into Motor Dysfunction in Clinical High Risk for Psychosis

Motor dysfunction in youth at clinical high risk (CHR) for psychosis is thought to reflect abnormal neurodevelopment within cortical-subcortical motor circuits and may be important for understanding clinical trajectories of CHR individuals. However, to date, our perspective of brain-behavior relationships has been informed solely by cross-sectional correlational studies linking behavior in the lab to brain structure or respective resting-state network connectivity. Here, we assess movement dysfunction from 2 perspectives: study 1 investigates the longitudinal progression of handwriting variability and positive symptoms in a sample of 91 CHR and healthy controls during a 12-month follow-up and study 2 involves a multiband functional magnetic resonance imaging task exploring the relationship between power grip force stability and motor network brain activation in a subset of participants. In study 1, we found that greater handwriting variability was a stable feature of CHR participants who experienced worse symptom progression. Study 2 results showed that CHR individuals had greater variability in their grip force and greater variability was related to decreased activation in the associative cortico-striatal network compared to controls. Motor variability may be a stable marker of vulnerability for psychosis risk and possible indicator of a vulnerable cortico-striatal brain network functioning in CHR participants, although the effects of antipsychotic medication should be considered.

Postural Control and Verbal and Visual Working Memory Correlates in Nonclinical Psychosis

INTRODUCTION

Motor and cognitive abnormalities are well documented in psychosis spectrum disorders. Evidence suggests these deficits could be pronounced because of disruptions in the cerebellar-thalamic-cortical-cerebellar (CTCC) circuit, a network thought to be heavily implicated in motor and higher cognitive functioning. Although significant research has been done on this topic in individuals with schizophrenia and those at a clinical high risk for psychosis, much less is known about deficits at the lower end of the spectrum.

METHODS

In this study, we extended the understanding of motor abnormalities across the psychosis continuum by examining postural sway deficits in the nonclinical psychosis (NCP) population. Furthermore, we linked these deficits to verbal and visual working memory. High-NCP (n = 37) and low-NCP control (n = 31) participants completed an instrumental balance task, highly sensitive to subtle variations in postural sway, along with a brief working memory battery.

RESULTS

We found that high-NCP participants presented with increased postural sway area (i.e., worse postural control) relative to low-NCP controls on a difficult condition (with limited proprioceptive cues), but not on an easier condition. Furthermore, results indicated that the sway area was correlated with poorer performance on working memory tasks in the high-NCP group.

CONCLUSION

These findings suggest that CTCC circuit abnormalities are present across the lower end of the psychosis spectrum and that they may be contributing to a range of motor and cognitive behaviors seen in the population. However, evidence suggests that the signs are subtle, and that sensitive assessment devices and challenging conditions may be necessary for detection.

Cerebellar Transcranial Direct Current Stimulation Improves Procedural Learning in Nonclinical Psychosis: A Double-Blind Crossover Study

The present double-blind crossover study examines the effects of cerebellar transcranial direct current stimulation (tDCS) in controls and in an analogue population to psychosis: individuals reporting elevated symptoms of nonclinical psychosis (NCP). A total of 18 controls and 24 NCP individuals were randomized into conditions consisting of 25 minutes of anodal (active) or sham cerebellar tDCS. Following this, both groups completed a pursuit rotor task designed to measure procedural learning performance. Participants then returned 1-week later and received the corresponding condition (either active or sham) and repeated the pursuit rotor task. Results indicate that in the sham condition, control participants showed significantly greater rates of motor learning when compared with the NCP group. In the active condition, the NCP group exhibited significant improvements in the rate of motor learning and performed at a level that was comparable to controls; these data support the link between cerebellar dysfunction and motor learning. Taken together, tDCS may be a promising treatment mechanism for patient populations and a useful experimental approach in elucidating our understanding of psychosis.

Speech illusions and working memory performance in non-clinical psychosis

Psychotic disorders are characterized by auditory verbal hallucinations (AVHs), and research has shown that AVHs are linked to deficits in working memory. Our understanding of AVHs across the psychosis continuum is limited. To date, little research has tested whether hallucination proneness (HP) is linked with abnormalities on experimental multispeaker babble tasks. Few investigations have been conducted to determine how task performance might be linked to cognitive functioning. The objective of the current study is to better understand this empirical gap. A total of 70 adults (30 healthy controls and 40 HP individuals) were administered an experimental task in which they listened to multispeaker babble and were instructed to report any words or chains of consecutive words (CCWs) perceived. Participants also were administered nonverbal and verbal working memory tasks. Findings revealed that relative to the control group, the HP individuals perceived more words and longer CCWs during the task. While there were no significant differences in working memory tasks between the HP and control groups, longer CCW's were associated with decreased verbal working memory scores in the HP group. AVH proneness may occur across a continuum of psychosis and may be linked with other theoretically relevant cognitive vulnerability factors.

Motor behavior reflects reduced hemispheric asymmetry in the psychosis risk period

BACKGROUND

A body of work focusing on brain connectivity, language dominance, and motor laterality research suggests that reduced hemispheric asymmetry is a core feature in schizophrenia. However, there is little consensus about whether reduced dominance is present in those at ultrahigh risk (UHR) for psychosis.

METHODS

A total of 94 demonstrated right-handed neuroleptic free participants (38 UHR and 56 matched healthy controls) were assessed with structured clinical interviews and completed an innovative handwriting task using a digital tablet computer. A laterality quotient (LQ) was calculated using kinematic variables from the participant's left and right hands. A subset of the sample (26 UHR and 29 controls) returned after 12-months to complete clinical interviews in order to examine relationships between handwriting laterality and progression of psychosis risk symptoms.

RESULTS

The UHR group showed decreased dextrality compared to healthy controls. At the 12-month follow-up, decreased dextrality accounted for 8% of the variance in worsened positive symptoms within the UHR group.

CONCLUSION

The current results suggest that disrupted cerebral dominance is also present in the ultrahigh risk period and that decreased dextrality may serve as a novel biomarker for the progression of psychosis risk.

Nicotine usage is associated with elevated processing speed, spatial working memory, and visual learning performance in youth at ultrahigh-risk for psychosis

Research has stressed a link between nicotine and cognition in schizophrenia but this has not been examined in youth at ultrahigh-risk (UHR) for psychosis. A total of 35 UHR and 32 control participants were assessed for naturalistic nicotine-use and administered a cognitive battery. Smoking was reported more frequently in the UHR group (46%) than controls (22%). Frequent smoking was associated with elevated cognitive performance in the UHR group, highlighting a need for experimental investigations.

Orbitofrontal cortex volume and intrinsic religiosity in non-clinical psychosis

Research indicates that religiosity plays a complex role in mental illness. Despite this link, little work has been done to clarify the role of religiosity in persons exhibiting non-clinical psychosis (NCP, individuals experiencing fleeting psychotic-like symptoms in the absence of a formal psychotic disorder). Further, there are no NCP investigations into whether abnormalities exist in brain structures that are associated with religiosity. Understanding these relationships in NCP is important to clarify the role of religiosity and brain structural anomalies in psychosis. Twenty individuals experiencing NCP and twenty controls were assessed for intrinsic religiosity (IR; motivation/commitment to religious beliefs and/or practices) using a well-validated self-report scale. Structural magnetic resonance imaging was used to determine volumes of the orbitofrontal cortex (OFC), a critical region that has been associated with increased religiosity. Results indicate that IR is elevated in the NCP group, and that these individuals exhibit bilateral volume reduction in both the lateral and medial OFC. Sample-wide correlations are non-significant, but show notable relationships between smaller OFC regions and increased IR. Significant negative relationships were found between OFC volume and depressive and negative symptoms. Overall, results suggest that brain abnormalities associated with NCP may also confer a heightened susceptibility for religiosity.

Cerebellar Morphology and Procedural Learning Impairment in Neuroleptic-Naive Youth at Ultrahigh Risk of Psychosis

Despite evidence suggesting a role for cerebellar abnormalities in the pathogenesis of psychosis, the structure has yet to receive attention in individuals at ultrahigh risk for psychosis (UHR). Accumulating research has suggested that the cerebellum helps modulate cognition and movement, domains in which UHR individuals show impairment; understanding putative markers of risk, such as structural abnormalities and behavioral correlates, is essential. In this study, participants underwent a high-resolution structural brain scan and participated in a pursuit rotor experiment. Cerebellar regions associated with movement (anterior cerebellum) and cognition (crus I) were subsequently analyzed. UHR participants showed impaired performance on the pursuit rotor task, learned at a slower rate, and showed smaller cerebellar volumes compared with control participants. Left crus I volume was significantly associated with poor rate of learning. The present results suggest that cerebellar abnormalities and their behavioral correlates (poor learning and motor control) precede the onset of psychosis.

Striatal abnormalities and spontaneous dyskinesias in non-clinical psychosis

BACKGROUND

Accumulating evidence suggests that individuals experiencing non-clinical psychosis (NCP) represent a critical group for improving understanding of etiological factors underlying the broader psychosis continuum. Although a wealth of evidence supports widespread neural dysfunction in formal psychosis, there has been little empirical evidence to inform our understanding of putative vulnerability markers or brain structure in NCP. In this study, we examined the neural correlates of spontaneous movement abnormalities, a biomarker previously detected in NCP that is linked to abnormalities in the striatal dopamine.

METHODS

We screened a total of 1285 adolescents/young adults, and those scoring in the upper 15th percentile on a NCP scale were invited to participate; 20 of those invited agreed and these individuals were matched with healthy controls. Participants were administered a structural scan, clinical interviews, and an instrumental motor assessment.

RESULTS

The NCP group showed elevated force variability and smaller putamen (but not caudate), and there was a significant relationship between motor dysfunction and striatal abnormalities for the sample. Elevated force variability was associated with both higher positive and negative symptoms, and there was a strong trend (p=.06) to suggest that smaller left putamen volumes were associated with elevated positive symptoms.

CONCLUSIONS

The results are among the first to suggest an association between neural structure and a risk marker in NCP. Findings indicate that vulnerabilities seen in schizophrenia also characterize the lower end of the psychosis spectrum.

Emotion recognition and social/role dysfunction in non-clinical psychosis

As researchers continue to understand non-clinical psychosis (NCP-brief psychotic-like experiences occurring in 5-7% of the general population; van Os et al., 2009), it is becoming evident that functioning deficits and facial emotion recognition (FER) impairment characterize this phenomenon. However, the extent to which these domains are related remains unclear. Social/role functioning and FER were assessed in 65 adolescents/young adults exhibiting low and high-NCP. Results indicate that FER and social/role functioning deficits were present in the High-NCP group, and that the domains were associated in this group alone. Taken together, findings suggest that a core emotive deficit is tied to broader social/role dysfunction in NCP.