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Effort discounting and its association with negative symptoms in schizophrenia

Introduction. Deficits in the initiation and persistence of goal-directed behaviour are key aspects of schizophrenia. In this study, the association between these motivational deficits and discounting of reward value in function of increasing physical effort costs was investigated. Methods. Effort-based decision-making was investigated in 40 patients with a DSM-IV diagnosis of schizophrenia and 30 age- and sex-matched healthy control subjects by means of an effort discounting task. To assess negative symptom severity, we made use of the Scale for the Assessment of Negative Symptoms as well as objective measurements of hedonic response to stimuli and motor activity levels. Results. Patients as well as control subjects discounted the subjective value of rewards significantly with increasing physical effort costs. However, we failed to find a difference in the discounting curves between patients and controls. Furthermore, effort discounting was not associated with any of the negative symptoms measures. Conclusions. Physical effort discounting was not found to be associated with motivational symptoms in schizophrenia if other decision costs are constant. However, recent findings show that more cognitive effort and/or an interaction between effort and other decision costs (e.g. temporal delay or uncertainty) are associated with negative symptoms in schizophrenia. This should be investigated further in future research.

Beyond Boundaries: In Search of an Integrative View on Motor Symptoms in Schizophrenia

MOTOR SYMPTOMS OF SCHIZOPHRENIA Schizophrenia is typically conceived as an illness characterized by positive, negative, and cognitive symptoms. However, most schizophrenia patients also display a wide range of symptoms characterized by aberrant motor functioning. Symptoms of schizophrenia that fit this description are catatonic features, the motoric neurological soft signs (NSS), extrapyramidal symptoms (EPS), psychomotor slowing, and reduced motor activity.

Quantitative Psychomotor Dysfunction in Schizophrenia: A Loss of Drive, Impaired Movement Execution or Both?

Aims: The aim of the present study was to investigate the predictive value of qualitative psychomotor performance levels and subaspects of the negative syndrome for quantitative motor activity levels in patients with schizophrenia. Methods: Twenty-seven stabilized patients with schizophrenia and 22 age- and sex-matched healthy controls were included in the study. An extensive battery of psychomotor performance tests (Finger Tapping Test, Purdue Pegboard Test, Line Copying Test, Neurological Evaluation Scale, Salpêtrière Retardation Rating Scale), clinical rating scales (Positive and Negative Syndrome Scale) and 24-hour actigraphy were administered to all participants. Results: Correlational analyses showed that motor activity levels were associated with avolition as well as clinically assessed psychomotor slowing. However, in a regression model, only avolition was found to be a significant predictor for motor activity levels in patients with schizophrenia; none of the psychomotor performance tests nor the severity of emotional expressivity deficits contributed to the model. Conclusion: Qualitative and quantitative psychomotor deficits seem to be independent phenomena in stabilized patients with schizophrenia. The diminishing in motor activity in patients with schizophrenia is related to a loss of drive and not to problems in the quality of movement execution.

Less cognitive and neurological deficits in schizophrenia patients carrying risk variant in ZNF804A.

Background: The rs1344706 single nucleotide polymorphism in the ZNF804A gene is a common variant with strong evidence for association with schizophrenia. Recent studies show an association of rs1344706 with cognitive functioning, and there is some evidence suggesting that the risk allele may increase susceptibility for a subtype of schizophrenia with relatively spared cognition. Methods: We tested the effect of rs1344706 genotype in 89 schizophrenia patients on 3 basic cognitive domains (working memory, processing speed and attention) shown to be severely impaired in schizophrenia. Also we investigated the effect of rs1344706 on the severity of neurological soft signs, subtle impairments in motor and sensory functions highly frequent in schizophrenia patients. Neurological soft signs and cognitive deficits are central features of schizophrenia and are tightly linked with clinical, social and functional outcome. Results: Our results show an association of higher rs1344706 risk allele load with improved performance on processing speed and with fewer neurological soft signs. Conclusions: Together with other studies, our findings suggest that ZNF804A is associated with a subtype of schizophrenia with better cognitive and neurological functioning. Discovery of the specific pathways through which ZNF804A is exerting this effect may lead to better prevention, diagnosis and treatment for a specific group of schizophrenia patients.

Psychomotor Retardation in Elderly Untreated Depressed Patients

Background: Psychomotor retardation (PR) is one of the core features in depression according to DSM V (1), but also aging in itself causes cognitive and psychomotor slowing. This is the first study investigating PR in relation to cognitive functioning and to the concomitant effect of depression and aging in a geriatric population ruling out contending effects of psychotropic medication. Methods: A group of 28 non-demented depressed elderly is compared to a matched control group of 20 healthy elderly. All participants underwent a test battery containing clinical depression measures, cognitive measures of processing speed, executive function and memory, clinical ratings of PR, and objective computerized fine motor skill-tests. Statistical analysis consisted of a General Linear Method multivariate analysis of variance to compare the clinical, cognitive, and psychomotor outcomes of the two groups. Results: Patients performed worse on all clinical, cognitive, and PR measures. Both groups showed an effect of cognitive load on fine motor function but the influence was significantly larger for patients than for healthy elderly except for the initiation time. Limitations: Due to the restrictive inclusion criteria, only a relatively limited sample size could be obtained. Conclusion: With a medication free sample, an additive effect of depression and aging on cognition and PR in geriatric patients was found. As this effect was independent of demand of effort (by varying the cognitive load), it was apparently not a motivational slowing effect of depression.

The nature of the relationship of psychomotor slowing with negative symptomatology in schizophrenia.

Introduction Psychomotor slowing is an important feature of schizophrenia and the relation with negative symptoms is not fully understood. This study aims, first, to investigate the association between negative symptoms and psychomotor slowing. Second, we want to investigate whether fine motor slowing reflects clinically observable gross motor slowing. Methods In 53 stabilised adult patients with schizophrenia, negative symptoms were assessed using the Positive and Negative Syndrome Scale negative subscale (PANSS-N) with two calculated factors entering the analysis: an expressivity factor and a volitional factor. Psychomotor slowing was assessed by using a modified version of the Salpêtrière Retardation Rating Scale, the Finger Tapping Test, and a writing task measuring fine psychomotor slowing. Results Negative symptomatology is associated with difficulties in the initiation of fine motor movements, r=.334, p<.05, whilst planning and execution are not. The volitional factor, r=−.407, p=.005, but not the expressivity factor, r=.060, p=.689, is significantly associated with psychomotor slowing. No associations between fine and clinically observable gross psychomotor functioning were found. Conclusions These findings indicate that higher values of negative symptomatology—more specifically the volitional deficit cluster—affect motor initiation, indicating a heterogeneity in the PANSS-N factorial structure, and that gross and fine psychomotor functioning are affected independently.

Longitudinal evaluation of the psychomotor syndrome in schizophrenia

Little is known about the longitudinal course of psychomotor signs and symptoms after illness onset in schizophrenia. Therefore, a 1-year follow-up study was conducted in which patients with schizophrenia were assessed three times with an extensive battery of psychomotor rating scales and tests. The syndromic structure of psychomotor symptoms was also studied. In accordance with a neurodevelopmental view on schizophrenia, psychomotor functioning was found to remain stable or improve slightly. Prospective studies with longer follow-up periods are needed to rule out the possibility of neurodegeneration in subgroups of patients and to evaluate possible covariation in the course of psychomotor symptoms.

White matter microstructure and volitional motor activity in schizophrenia: A diffusion kurtosis imaging study

Avolition is a core feature of schizophrenia and may arise from altered brain connectivity. Here we used diffusion kurtosis imaging (DKI) to investigate the association between white matter (WM) microstructure and volitional motor activity. Multi-shell diffusion MRI and 24-h actigraphy data were obtained from 20 right-handed patients with schizophrenia and 16 right-handed age and gender matched healthy controls. We examined correlations between fractional anisotropy (FA), mean diffusivity (MD), mean kurtosis (MK), and motor activity level, as well as group differences in these measures. In the patient group, increasing motor activity level was positively correlated with MK in the inferior, medial and superior longitudinal fasciculus, the corpus callosum, the posterior fronto-occipital fasciculus and the posterior cingulum. This association was not found in control subjects or in DTI measures. These results show that a lack of volitional motor activity in schizophrenia is associated with potentially altered WM microstructure in posterior brain regions associated with cognitive function and motivation. This could reflect both illness related dysconnectivity which through altered cognition, manifests as reduced volitional motor activity, and/or the effects of reduced physical activity on brain WM.

Abnormal emotion processing, but intact fairness and intentionality considerations during social decision-making in schizophrenia

Schizophrenia is a severe mental disorder that is highly characterized by social cognitive impairments. Most studies investigating these impairments focus on one specific social domain such as emotion recognition. However, in daily life, processing complex social situations relies on the combination of several social cognitive and affective processes simultaneously rather than one process alone. A modified version of the economically based Ultimatum Game was used to measure the interplay between fairness, intentionality, and emotion considerations during social decision-making. In this task, participants accept or reject fair and unfair monetary offers proposed intentionally or unintentionally by either angry, happy, neutral, or sad proposers. Behavioral data was collected from a group of schizophrenia patients (N = 35) and a group of healthy individuals (N = 30). Like healthy participants, schizophrenia patients differentiated between fair and unfair offers by rejecting unfair offers more compared to fair offers. However, overall patients did reject more fair offers, indicating that their construct of fairness operates within different margins. In both groups, intentional unfair offers were rejected more compared to unintentional ones, indicating a normal integration of intentionality considerations in schizophrenia. Importantly, healthy subjects also differentiated between proposers’ emotion when rejecting unfair offers (more rejections from proposers depicting angry faces compared to proposers depicting, happy, neutral, or sad faces). Schizophrenia patients’ decision behavior on the other hand, was not affected by the proposers’ emotions. The current study thus shows that schizophrenia patients have specific problems with processing and integrating emotional information. Importantly, the finding that patients display normal fairness and intentionality considerations emphasizes preservation of central social cognitive processes in schizophrenia.

Cognitive and psychomotor effects of three months of escitalopram treatment in elderly patients with major depressive disorder

BACKGROUND Although psychomotor retardation (PR) and cognitive disfunctioning are essential symptoms of elderly depressed patients, the differential effect of treatment with an SSRI in the elderly on these symptoms has hardly got any attention in studies with objective experimental measures. Since effects appear relatively slower in elderly, this study evaluates the effect on cognitive and psychomotor functioning as compared to mood, on four points during a twelve week follow up of monotreatment with escitalopram. METHOD 28 non-demented elderly unipolar depressive patients on 5-20mg escitalopram were compared to 20 matched healthy elderly. All participants underwent a test battery containing clinical depression measures, cognitive measures of processing speed, executive function and memory, clinical ratings of PR, and objective computerized fine motor skill-tests at the start and after 2, 6 and 12 weeks. Statistical analysis consisted of a General Linear Model (GLM) repeated measures multivariate analysis of variance of completers to compare the psychomotor and cognitive outcomes of the two groups. RESULTS Although, apart from the significant mood effect, no interaction effects were found for the psychomotor and cognitive tasks, the means in general show a trend of differential effects in cognitive and psychomotor functions, with smaller effects and delayed timeframes and with presence of subgroups compared to mood effects. LIMITATION Longer follow up studies are necessary to evaluate differential long term effects. CONCLUSION In elderly, moderate effects of SSRI treatment on mood precede slow or limited effects on cognition and psychomotor retardation.