Socioaffective factors modulate working memory in schizophrenia patients

Intrinsic Connectivity Patterns of Task-Defined Brain Networks Allow Individual Prediction of Cognitive Symptom Dimension of Schizophrenia and Are Linked to Molecular Architecture

BACKGROUND

Despite the marked interindividual variability in the clinical presentation of schizophrenia, the extent to which individual dimensions of psychopathology relate to the functional variability in brain networks among patients remains unclear. Here, we address this question using network-based predictive modeling of individual psychopathology along 4 data-driven symptom dimensions. Follow-up analyses assess the molecular underpinnings of predictive networks by relating them to neurotransmitter-receptor distribution patterns.

METHODS

We investigated resting-state functional magnetic resonance imaging data from 147 patients with schizophrenia recruited at 7 sites. Individual expression along negative, positive, affective, and cognitive symptom dimensions was predicted using a relevance vector machine based on functional connectivity within 17 meta-analytic task networks following repeated 10-fold cross-validation and leave-one-site-out analyses. Results were validated in an independent sample. Networks robustly predicting individual symptom dimensions were spatially correlated with density maps of 9 receptors/transporters from prior molecular imaging in healthy populations.

RESULTS

Tenfold and leave-one-site-out analyses revealed 5 predictive network-symptom associations. Connectivity within theory of mind, cognitive reappraisal, and mirror neuron networks predicted negative, positive, and affective symptom dimensions, respectively. Cognitive dimension was predicted by theory of mind and socioaffective default networks. Importantly, these predictions generalized to the independent sample. Intriguingly, these two networks were positively associated with D₁ receptor and serotonin reuptake transporter densities as well as dopamine synthesis capacity.

CONCLUSIONS

We revealed a robust association between intrinsic functional connectivity within networks for socioaffective processes and the cognitive dimension of psychopathology. By investigating the molecular architecture, this work links dopaminergic and serotonergic systems with the functional topography of brain networks underlying cognitive symptoms in schizophrenia.

Effects of reward on spatial working memory in schizophrenia

Reward processing and cognition are disrupted in schizophrenia (SCZ), yet how these processes interface is unknown. In SCZ, deficits in reward representation may affect motivated, goal-directed behaviors. To test this, we examined the effects of monetary reward on spatial working memory (WM) performance in patients with SCZ. To capture complimentary effects, we tested biophysically grounded computational models of neuropharmacologic manipulations onto a canonical fronto-parietal association cortical microcircuit capable of WM computations. Patients with SCZ (n = 33) and healthy control subjects (HCS; n = 32) performed a spatial WM task with 2 reward manipulations: reward cues presented prior to each trial, or contextually prior to a block of trials. WM performance was compared with cortical circuit models of WM subjected to feed-forward glutamatergic excitation, feed-forward GABAergic inhibition, or recurrent modulation strengthening local connections. Results demonstrated that both groups improved WM performance to reward cues presented prior to each trial (HCS d = -0.62; SCZ d = -1.0), with percent improvement correlating with baseline WM performance (r = .472, p < .001). However, rewards presented contextually before a block of trials did not improve WM performance in patients with SCZ (d = 0.01). Modeling simulations achieved improved WM precision through strengthened local connections via neuromodulation, or feed-forward inhibition. Taken together, this work demonstrates that patients with SCZ can improve WM performance to short-term, but not longer-term rewards-thus, motivated behaviors may be limited by strength of reward representation. A potential mechanism for transiently improved WM performance may be strengthening of local fronto-parietal microcircuit connections via neuromodulation or feed-forward inhibitory drive. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

What accounts for poor functioning in people with schizophrenia: a re-evaluation of the contributions of neurocognitive v. attitudinal and motivational factors

BACKGROUND

Neurocognitive deficits are often seen as core features of schizophrenia, and as primary determinants of poor functioning. Yet, our clinical observations suggest that individuals who score within the impaired range on standardized tests can reliably perform better in complex real-world situations, especially when performance is embedded within a positive socio-affective context.

METHODS

We analyzed literature on the influence of non-neurocognitive factors on test performance in order to clarify their contributions.

RESULTS

We identified seven non-neurocognitive factors that significantly contribute to neurocognitive test performance: avolition, dysfunctional attitudes, effort, stress, negative emotions, asociality, and disorganized symptoms. We then proposed an alternative model based on dysfunctional (e.g. defeatist) attitudes and their consequences for motivation and sustained task engagement. We demonstrated that these factors account for substantial variance in negative symptoms, neurocognitive test performance, and functional outcomes. We then demonstrated that recovery-oriented cognitive therapy - which is derived from this alternative model and primarily targets dysfunctional beliefs - has been successful in the treatment of low functioning individuals with schizophrenia.

CONCLUSION

The contributions of neurocognitive impairments to poor real-world functioning in people with schizophrenia may be overstated in the literature, and may even be limited relative to non-neurocognitive factors. We offer suggestions for further research to more precisely quantify the contributions of attitudinal/motivation v. neurocognitive factors in schizophrenia.

Where did I put my keys? - a 'we' intervention to promote memory in healthy older adults: a controlled pilot study

BACKGROUND

Numerous behavioural studies have shown that older adults have more difficulty in binding things together and have underlined the corresponding importance of this function in everyday memory tasks.

OBJECTIVE

This study was designed to test a new brief inter-dependent self-knowledge intervention on memory functions in aging.

METHODS

Before engaging in a working memory task based on binding objects and their locations, half of the participants read a series of paragraphs that focused on the individual self and were written in the first person singular 'I' (in-dependent self-knowledge), whereas the other half read paragraphs that focused on the relational self and were written in the first person plural 'We' (inter-dependent self-knowledge).

RESULTS

Results showed that older adults who were trained with 'We' passages were more successful in remembering objects and their location compared to the group of participants who were trained with 'I' passages.

CONCLUSION

These findings are discussed in terms of the role that social factors may have in favouring memory functions in aging and delineate a new cognitive clinical protocol based on an inter-dependent self-knowledge approach.

Mental imagery and visual working memory

Visual working memory provides an essential link between past and future events. Despite recent efforts, capacity limits, their genesis and the underlying neural structures of visual working memory remain unclear. Here we show that performance in visual working memory--but not iconic visual memory--can be predicted by the strength of mental imagery as assessed with binocular rivalry in a given individual. In addition, for individuals with strong imagery, modulating the background luminance diminished performance on visual working memory and imagery tasks, but not working memory for number strings. This suggests that luminance signals were disrupting sensory-based imagery mechanisms and not a general working memory system. Individuals with poor imagery still performed above chance in the visual working memory task, but their performance was not affected by the background luminance, suggesting a dichotomy in strategies for visual working memory: individuals with strong mental imagery rely on sensory-based imagery to support mnemonic performance, while those with poor imagery rely on different strategies. These findings could help reconcile current controversy regarding the mechanism and location of visual mnemonic storage.

Bridging the gap between extrinsic and intrinsic motivation in the cognitive remediation of schizophrenia

An important development in cognitive remediation of schizophrenia is a focus on motivation. However, following a distinction between the concepts of intrinsic motivation (IM) and extrinsic motivation, discussions of IM-based methods have downplayed or misrepresented the role that extrinsic rewards can, and actually do, serve to promote positive treatment outcomes in cognitive remediation. Therefore, the purpose of this article is to explore the rationale for using techniques incorporating extrinsic rewards into cognitive treatment of people with schizophrenia. To do this, evidence is presented on each of the following points: (1) there is a long history of research demonstrating that delivery of extrinsic reward is associated with positive outcomes in both behavioral and cognitive rehabilitation; (2) basic human brain systems respond strongly to tangible rewards, and this can directly enhance attention, working memory, and other cognitive functions; (3) nearly all data on the negative effects of extrinsic reward on IM have come from studies of healthy children and adults in school or work settings who have adequate IM for target tasks; these findings do not generalize well to cognitive remediation settings for people with schizophrenia, who often have abnormally low levels of IM and low base rates of attentive behaviors; and (4) in real-world situations, cognitive remediation interventions already utilize a combination of intrinsic and extrinsic reinforcers. Future studies are needed to clarify state and trait factors responsible for individual differences in the extent to which extrinsic rewards are necessary to set the conditions under which IM can develop.

Attention shaping: a reward-based learning method to enhance skills training outcomes in schizophrenia

Disturbances in sustained attention commonly interfere with the ability of persons with schizophrenia to benefit from evidence-based psychosocial treatments. Cognitive remediation interventions have thus far demonstrated minimal effects on attention, as have medications. There is thus a gap between the existence of effective psychosocial treatments and patients' ability to effectively engage in and benefit from them. We report on the results of a multisite study of attention shaping (AS), a behavioral intervention for improving attentiveness and learning of social skills among highly distractible schizophrenia patients. Patients with chronic schizophrenia who were refractory to skills training were assigned to receive either the UCLA Basic Conversation Skills Module (BCSM) augmented with AS (n = 47) or in the standard format (n = 35). AS, a reward-based learning procedure, was employed to facilitate patients' meeting clearly defined and individualized attentiveness and participation goals during each session of a social skills training group. Primary outcome measures were observational ratings of attentiveness in each session and pre- and post-BCSM ratings of social skill and symptoms. Patients receiving social skills training augmented with AS demonstrated significantly more attentiveness in group sessions and higher levels of skill acquisition; moreover, significant relationships were found between changes in attentiveness and amount of skills acquired. Changes in attentiveness were unrelated to level or change in antipsychotic medication dose. AS is an effective example of supported cognition, in that cognitive abilities are improved within the environmental context where the patient is experiencing difficulty, leading to gains in both attention and functional outcome.

Measuring specific, rather than generalized, cognitive deficits and maximizing between-group effect size in studies of cognition and cognitive change

While cognitive impairment in schizophrenia is easy to demonstrate, it has been much more difficult to measure a specific cognitive process unconfounded by the influence of other cognitive processes and noncognitive factors (eg, sedation, low motivation) that affect test scores. With the recent interest in the identification of neurophysiology-linked cognitive probes for clinical trials, the issue of isolating specific cognitive processes has taken on increased importance. Recent advances in research design and psychometric theory regarding cognition research in schizophrenia demonstrate the importance of (1) maximizing between-group differences via reduction of measurement error during both test development and subsequent research and (2) the development and use of process-specific tasks in which theory-driven performance indices are derived across multiple conditions. Use of these 2 strategies can significantly advance both our understanding of schizophrenia and measurement sensitivity for clinical trials. Novel data-analytic strategies for analyzing change across multiple conditions and/or multiple time points also allow for increased reliability and greater measurement sensitivity than traditional strategies. Following discussion of these issues, trade-offs inherent to attempts to address psychometric issues in schizophrenia research are reviewed. Finally, additional considerations for maximizing sensitivity and real-world significance in clinical trials are discussed.

Executive function in schizophrenia: what impact do antipsychotics have?

Cognitive dysfunction is a major component of schizophrenia, with deficits in executive function particularly pertinent to successful daily living and outcome. Executive deficits and negative/disorganised symptoms remain relatively resistant to amelioration by antipsychotic medication in comparison to positive symptoms. While there is a relative paucity of data on the effects of antipsychotics on specific executive deficits, atypical antipsychotics would appear to be more beneficial than typical antipsychotics at improving these functions, with muscarinic, glutamatergic and cholinergic systems variously implicated. Recent research focusing on the relationships between specific symptoms and specific executive deficits holds important implications for future psychopharmacological interventions in the area by elucidating the neural substrates and pathways which underpin schizophrenic symptomatology. This review attempts to evaluate the research thus far for the specific executive components of spatial working memory (SWM), inhibition, sustained attention and set shifting. Issues significant to future psychopharmacology in the area are discussed, with particular emphasis on the need for a greater consensus in methodology and definition executive function research in schizophrenia.