Both unmedicated and medicated individuals with schizophrenia show impairments across a wide array of cognitive and reinforcement learning tasks

Anticholinergic Burden and Cognitive Function in Psychosis: A Systematic Review and Meta-Analysis

OBJECTIVE

The authors synthesized evidence from studies quantifying the relationship between anticholinergic medication and cognitive function in psychosis, and additionally explored studies that investigated whether reducing anticholinergic medications affects cognitive function in individuals with psychosis.

METHODS

A database search was conducted in MEDLINE, Embase, and PsycINFO, from database inception to October 2023, for studies reporting objective cognitive assessment and quantification of anticholinergic burden using clinical scales, serological anticholinergic activity, or tapering of anticholinergic medications. Analyses were carried out in R using the metafor package. Random-effects meta-analysis models were employed, along with assessment of heterogeneity, study quality, and meta-regressions (age, sex, and antipsychotic dosage in chlorpromazine equivalents).

RESULTS

Of 1,337 citations retrieved, 40 met inclusion criteria, comprising 25 anticholinergic burden studies (4,620 patients), six serological anticholinergic activity studies (382 patients), and nine tapering studies (186 patients). A negative correlation was identified between anticholinergic burden and global cognition (r=-0.37, 95% CI=-0.48, -0.25), verbal learning (r=-0.28, 95% CI=-0.36, -0.21), visual learning (r=-0.17, 95% CI=-0.28, -0.06), working memory (r=-0.22, 95% CI=-0.29, -0.14), processing speed (r=-0.24, 95% CI=-0.35, -0.13), attention (r=-0.19, 95% CI=-0.29, -0.08), executive functions (r=-0.17, 95% CI=-0.27, -0.06), and social cognition (r=-0.12, 95% CI=-0.19, -0.05), and between serological anticholinergic activity and verbal learning (r=-0.26, 95% CI=-0.38, -0.14), working memory (r=-0.19, 95% CI=-0.35, -0.03), and executive functions (r=-0.16, 95% CI=-0.27, -0.04). Finally, tapering off anticholinergic medication improved the scores in verbal learning (d=0.77, 95% CI=0.44, 1.1), working memory (d=0.94, 95% CI=0.63, 1.26), and executive functions (d=0.44, 95% CI=0.26, 0.62).

CONCLUSIONS

Anticholinergic burden is associated with the cognitive impairments observed in psychosis. From a clinical perspective, tapering off anticholinergic medication in patients with psychosis may improve cognition. However, randomized clinical trials are needed for an unbiased quantification of benefit.

Impaired Contour Object Perception in Psychosis

BACKGROUND

Contour integration, the process of joining spatially separated elements into a single unified line, has consistently been found to be impaired in schizophrenia. Recent work suggests that this deficit could be associated with psychotic symptomatology rather than a specific diagnosis such as schizophrenia.

METHODS

Examining a transdiagnostic sample of participants with psychotic psychopathology, we obtained quantitative indices of contour perception in a psychophysical behavioral task. We also measured responses during an analogous task using ultra-high field (7T) functional magnetic resonance imaging (fMRI).

RESULTS

We found impaired contour discrimination performance among people with psychotic psychopathology (PwPP) (n = 63) compared with healthy control participants (n = 34) and biological relatives of PwPP (n = 44). Participants with schizophrenia (n = 31) showed impaired task performance compared with participants with bipolar disorder (n = 18). fMRI showed higher responses in the lateral occipital cortex of PwPP than in control participants. Using task-based functional connectivity analyses, we observed abnormal connectivity between visual brain areas during contour perception among PwPP. These connectivity differences only emerged when participants had to distinguish the contour object from background distractors, suggesting that a failure to suppress noise elements relative to contour elements may underlie impaired contour processing in PwPP.

CONCLUSIONS

Our results are consistent with impaired contour integration in psychotic psychopathology, and especially schizophrenia, that is related to cognitive dysfunction and may be linked to impaired functional connectivity across visual regions.

Motivation and Pleasure Deficits Undermine the Benefits of Social Affiliation in Psychosis

In psychotic disorders, motivation and pleasure (MAP) deficits are associated with decreased affiliation and heightened functional impairment. We leveraged a transdiagnostic sample enriched for psychosis and a multi-method approach to test the hypothesis that MAP deficits undermine the stress-buffering benefits of affiliation. Participants completed the Social Affiliation Enhancement Task (SAET) to cultivate affiliation with an experimental partner. Although the SAET increased perceived affiliation and mood, individuals with greater negative symptoms derived smaller emotional benefits from the partners, as indexed by self-report and facial behavior. We then used the Handholding fMRI paradigm, which combines threat-anticipation with affiliative physical contact, to determine whether MAP deficits undermine the social regulation of distress. Individuals with greater MAP deficits showed diminished neural 'benefits'-reduced dampening of threat-elicited activation-from affiliative touch in key frontoparietal nodes of the Dorsal Attention Network. In short, MAP symptoms disrupt the emotional and neuroregulatory benefits of affiliation.

A measure of reliability convergence to select and optimize cognitive tasks for individual differences research

Surging interest in individual differences has faced setbacks in light of recent replication crises in psychology, for example in brain-wide association studies exploring brain-behavior correlations. A crucial component of replicability for individual differences studies, which is often assumed but not directly tested, is the reliability of the measures we use. Here, we evaluate the reliability of different cognitive tasks on a dataset with over 250 participants, who each completed a multi-day task battery. We show how reliability improves as a function of number of trials, and describe the convergence of the reliability curves for the different tasks, allowing us to score tasks according to their suitability for studies of individual differences. We further show the effect on reliability of measuring over multiple time points, with tasks assessing different cognitive domains being differentially affected. Data collected over more than one session may be required to achieve trait-like stability.

Impaired contour object perception in psychosis

Contour integration, the process of joining spatially separated elements into a single unified line, has consistently been found to be impaired in schizophrenia. Recent work suggests that this deficit could be associated with psychotic symptomatology, rather than a specific diagnosis such as schizophrenia. Examining a transdiagnostic sample of participants with psychotic psychopathology, we obtained quantitative indices of contour perception in a psychophysical behavioral task. We found impaired contour discrimination performance among people with psychotic psychopathology (PwPP, n = 62) compared to healthy controls (n = 34) and biological relatives of PwPP (n = 44). Participants with schizophrenia (n = 31) showed impaired task performance compared to participants with bipolar disorder (n = 18). We also measured responses during an analogous task using ultra-high field (7T) functional MRI and found higher responses in the lateral occipital cortex of PwPP compared to controls. Using task-based functional connectivity analyses, we observed abnormal connectivity between visual brain areas during contour perception among PwPP. These connectivity differences only emerged when participants had to distinguish the contour object from background distractors, suggesting that a failure to suppress noise elements relative to contour elements may underlie impaired contour processing in PwPP. Our results are consistent with impaired contour integration in psychotic psychopathology, and especially schizophrenia, that is related to cognitive dysfunction, and may be linked to impaired functional connectivity across visual regions.

Transdiagnostic Predictors of Everyday Functioning: Examining the Relationships of Depression and Reinforcement Learning

BACKGROUND AND HYPOTHESIS

Impairments in function (ie, the ability to independently accomplish daily tasks) have been established in psychotic disorders. Identifying factors that contribute to these deficits is essential to developing effective interventions. The current study had several goals: examine potential differential relationships across domains of neurocognition, assess whether reinforcement learning is related to function, identify if predictors of function are transdiagnostic, determine whether depression and positive symptoms contribute to function, and to explore whether the modality of assessment impacts observed relationships.

STUDY DESIGN

Data from 274 participants were examined with schizophrenia/schizoaffective disorder (SZ; n = 195) and bipolar disorder (BD; n = 79). To reduce dimensionality, a PCA was completed on neurocognitive tasks which resulted in 3 components. These components and clinical interview data were used to investigate predictors of functional domains across measures of function (self- and informant-report SLOF and UPSA).

RESULTS

Two components, working memory/processing speed/episodic memory (βs = 0.18-0.42), and negative/positive reinforcement learning (β = -0.04), predicted different functional domains. Predictors of function were largely transdiagnostic with two exceptions: reinforcement learning had a positive association with self-reported interpersonal relationships for SZ and a negative association for BD (β = 0.34), and the negative association between positive symptoms and self-reported social acceptability was stronger for BD than for SZ (β = 0.93). Depression robustly predicted self-reported but not informant-reported function, and anhedonia predicted all domains of informant-reported function.

CONCLUSIONS

These findings imply that reinforcement learning may differentially relate to function across disorders, traditional domains of neurocognition can be effective transdiagnostic targets for interventions, and positive symptoms and depression play a critical role in self-perceived functional impairments.

Spatiotemporal Alterations in Working Memory-Related Beta Band Neuromagnetic Activity of Patients With Schizophrenia On and Off Antipsychotic Medication: Investigation With MEG

BACKGROUND AND HYPOTHESIS

We used the uniquely high combined spatial and temporal resolution of magnetoencephalography to characterize working memory (WM)-related modulation of beta band activity in neuroleptic-free patients with schizophrenia in comparison to a large sample of performance-matched healthy controls. We also tested for effects of antipsychotic medication on identified differences in these same patients.

STUDY DESIGN

Inpatients with schizophrenia (n = 21) or psychotic disorder not otherwise specified (n = 4) completed N-back and control tasks during magnetoencephalography while on placebo and during antipsychotic medication treatment, in a blinded, randomized, counterbalanced manner. Healthy, performance-matched controls (N = 100) completed the same tasks. WM-related neural activation was estimated as beta band (14-30 Hz) desynchronization throughout the brain in successive 400 ms time windows. Voxel-wise statistical comparisons were performed between controls and patients while off-medication at each time window. Significant clusters resulting from this between-groups analysis were then used as regions-of-interest, the activations of which were compared between on- and off-medication conditions in patients.

STUDY RESULTS

Controls showed beta-band desynchronization (activation) of a fronto-parietal network immediately preceding correct button press responses-the time associated with WM updating and task execution. Altered activation in medication-free patients occurred largely during this time, in prefrontal, parietal, and visual cortices. Medication altered patients' neural responses such that the activation time courses in these regions-of-interest more closely resembled those of controls.

CONCLUSIONS

These findings demonstrate that WM-related beta band alterations in schizophrenia are time-specific and associated with neural systems targeted by antipsychotic medications. Future studies may investigate this association by examining its potential neurochemical basis.

Using Nonhuman Primate Models to Reverse-Engineer Prefrontal Circuit Failure Underlying Cognitive Deficits in Schizophrenia

In this chapter, I review studies in nonhuman primates that emulate the circuit failure in prefrontal cortex responsible for working memory and cognitive control deficits in schizophrenia. These studies have characterized how synaptic malfunction, typically induced by blockade of NMDAR, disrupts neural function and computation in prefrontal networks to explain errors in cognitive tasks that are seen in schizophrenia. This work is finding causal relationships between pathogenic events of relevance to schizophrenia at vastly different levels of scale, from synapses, to neurons, local, circuits, distributed networks, computation, and behavior. Pharmacological manipulation, the dominant approach in primate models, has limited construct validity for schizophrenia pathogenesis, as the disease results from a complex interplay between environmental, developmental, and genetic factors. Genetic manipulation replicating schizophrenia risk is more advanced in rodent models. Nonetheless, gene manipulation in nonhuman primates is rapidly advancing, and primate developmental models have been established. Integration of large scale neural recording, genetic manipulation, and computational modeling in nonhuman primates holds considerable potential to provide a crucial schizophrenia model moving forward. Data generated by this approach is likely to fill several crucial gaps in our understanding of the causal sequence leading to schizophrenia in humans. This causal chain presents a vexing problem largely because it requires understanding how events at very different levels of scale relate to one another, from genes to circuits to cognition to social interactions. Nonhuman primate models excel here. They optimally enable discovery of causal relationships across levels of scale in the brain that are relevant to cognitive deficits in schizophrenia. The mechanistic understanding of prefrontal circuit failure they promise to provide may point the way to more effective therapeutic interventions to restore function to prefrontal networks in the disease.

Episodic Memory and Schizophrenia: From Characterization of Relational Memory Impairments to Neuroimaging Biomarkers

Episodic memory research in schizophrenia has a long history already which has clearly established significant impairments and strong associations with brain measures and functional outcome. The purpose of this chapter is not to make an exhaustive review of the recent literature but to highlight some relatively recent developments in the cognitive neuroscience field of episodic memory and schizophrenia. Hence, we present a contemporary view focusing specifically of relational memory which represents a form of episodic memory that refers to associations or binding among items or elements presented together. We describe the major tasks used and illustrate how their combination with brain imaging has: (1) favored the use of experimental memory tasks to isolate specific processes with specific neural correlates, (2) led to a distributed view of the neural correlates of memory impairments in schizophrenia where multiple regions are contributing, and (3) made possible the identification of fMRI biomarkers specific to episodic memory. We then briefly propose what we see as the next steps for memory research in schizophrenia so that the impact of this work can be maximized.

Reduced learning bias towards the reward context in medication-naive first-episode schizophrenia patients

BACKGROUND

Reinforcement learning has been proposed to contribute to the development of amotivation in individuals with schizophrenia (SZ). Accumulating evidence suggests dysfunctional learning in individuals with SZ in Go/NoGo learning and expected value representation. However, previous findings might have been confounded by the effects of antipsychotic exposure. Moreover, reinforcement learning also rely on the learning context. Few studies have examined the learning performance in reward and loss-avoidance context separately in medication-naïve individuals with first-episode SZ. This study aimed to explore the behaviour profile of reinforcement learning performance in medication-naïve individuals with first-episode SZ, including the contextual performance, the Go/NoGo learning and the expected value representation performance.

METHODS

Twenty-nine medication-naïve individuals with first-episode SZ and 40 healthy controls (HCs) who have no significant difference in age and gender, completed the Gain and Loss Avoidance Task, a reinforcement learning task involving stimulus pairs presented in both the reward and loss-avoidance context. We assessed the group difference in accuracy in the reward and loss-avoidance context, the Go/NoGo learning and the expected value representation. The correlations between learning performance and the negative symptom severity were examined.

RESULTS

Individuals with SZ showed significantly lower accuracy when learning under the reward than the loss-avoidance context as compared to HCs. The accuracies under the reward context (90%win- 10%win) in the Acquisition phase was significantly and negatively correlated with the Scale for the Assessment of Negative Symptoms (SANS) avolition scores in individuals with SZ. On the other hand, individuals with SZ showed spared ability of Go/NoGo learning and expected value representation.

CONCLUSIONS

Despite our small sample size and relatively modest findings, our results suggest possible reduced learning bias towards reward context among medication-naïve individuals with first-episode SZ. The reward learning performance was correlated with amotivation symptoms. This finding may facilitate our understanding of the underlying mechanism of negative symptoms. Reinforcement learning performance under the reward context may be important to better predict and prevent the development of schizophrenia patients' negative symptom, especially amotivation.

Early Recognition Method - Amplifying relapse management in community mental health care; a comprehensive study of the effects on relapse and readmission

This naturalistic multicenter study explored the relationship between participating in the Early Recognition Method (ERM) intervention and relapse, defined as spending at least one night at a psychiatric ward. The intervention was tailored to adult patients with schizophrenia or bipolar disorder in an outpatient mental health care setting. Before the intervention, the staff received training in application of the strategy. The ERM strategy is protocolized and includes identification and monitoring of individual early warning signs and development of a personal plan of action. The study showed a reduction in mean number and duration of readmissions during the period the patients participated in the intervention, compared to an equal pre-intervention period. For patients with bipolar disorder the reduction was statistical significant. The difference in outcome between the two diagnostic groups suggests that further tailoring of the application of the ERM strategy might improve the relapse prevention outcome.