Neural correlates of exercise training in individuals with schizophrenia and in healthy individuals: A systematic review

A body of evidence has revealed positive effects of physical exercise on behavioral, cognitive and physical outcomes in patients with schizophrenia. Notably, the effect of exercise at the neural level may be particularly relevant as well as it is hypothesized that exercise may stimulate the brain in a way that might normalize neural alterations related to the disorder. The aim of the current systematic review was to provide an up to date overview of studies investigating the neural effects of exercise in individuals with a schizophrenia spectrum disorder and healthy individuals. The majority of included studies focused on hippocampal effects, reporting beneficial effects of exercise. In addition, in schizophrenia increased extrastriate body area (EBA) activation and increased white matter fiber integrity in tracts relevant to the disorder were found and in healthy individuals decreased connectivity of the dorsolateral prefrontal cortex (DLPFC) indicating greater cognitive efficiency was reported. Comparing individuals with a schizophrenia spectrum disorder and healthy individuals within a similar age range, most studies found similar effects on hippocampal volume and white matter tracts for both groups, although the effect in schizophrenia spectrum disorders may be attenuated which is in line with previous literature on brain plasticity. The current review indicates a lack of studies investigating neural correlates other than the hippocampus. Although those studies that did focus on other neural correlates revealed promising results, these have not been replicated in other studies and call for replication. Furthermore, future studies should expand their focus, by investigating neural mechanisms underlying positive effects of physical exercise on positive symptoms, negative symptoms and symptoms such as depression, social withdrawal and social cognition.

[rTMS for treatment resistant depression - proposal for a treatment protocol]

At present, the use of repetitive transcranial magnetic stimulation (rtms) for treatment-resistant depression is sufficiently substantiated to be applied in clinical practice. In the Netherlands, it will be reimbursed when offered in combination with cognitive behavior therapy.<br/> AIM: Proposal for a clinical treatment protocol for rtms in The Netherlands.<br/> METHOD: A study of the literature and a critical appraisal of available international guidelines for rtms.<br/> RESULTS: rtms is a safe treatment for patients suffering from a moderate to severe depressive disorder that is relatively treatment-resistant. The duration of the effect is still unknown. It is advised to stimulate the left dorsolateral prefrontal cortex using an intensity of 120% of the resting motor threshold, with a frequency of 10 Hz and using 3000 pulses per session during a total of 20-30 sessions.<br/> CONCLUSION: The proposed treatment protocol is favored based on the available evidence when rtms is used as a treatment aimed to acutely decrease the severity of depressive symptoms. It is further proposed to systematically collect technical and outcome data on treatment with rtms to further improve treatment with rtms in clinical practice.

Differential Neural Correlates of Dimensions of Negative Symptoms in Schizophrenia During Social-emotional Appraisal and Effects of Treatment

Factor analyses of large datasets have established two dimensions of negative symptoms: expressive deficits and a motivation. This distinction is of relevance as the dimensions differ in their cognitive and clinical correlates (e.g. with regard to functional outcome). Using functional MRI, we examined the neural correlates of the two negative symptom dimensions with brain activation during social-emotional evaluation. Patients with schizophrenia (n = 38) and healthy controls (n = 20) performed the Wall of Faces task during fMRI, which measures emotional ambiguity in a social context by presenting an array of faces with varying degrees of consistency in emotional expressions. More specifically, appraisal of facial expressions under uncertainty. We found severity of expressive deficits to be negatively correlated with activation in thalamic, prefrontal, precentral, parietal and temporal brain areas during emotional ambiguity (appraisal of facial expressions in an equivocal versus an unequivocal condition). No association was found for a motivation with these neural correlates, in contrast to a previous fMRI study in which we found a motivation to be associated with neural correlates of executive (planning) performance. We also evaluated the effects of medication and neurostimulation (rTMS treatment over the lateral prefrontal cortex) on activation during the social–emotional ambiguity task. The medication comparison concerned an RCT of aripiprazole versus risperidone. Compared to risperidone, aripiprazole showed differential involvement of frontotemporal and frontostriatal circuits in social-emotional ambiguity. We conclude that deconstruction of negative symptoms into more homogeneous components and investigating underlying neurocognitive mechanisms can potentially shed more light on their nature and may ultimately yield clues for targeted treatment.

Disclosure of interest

AA received speaker fees from Lundbeck.

[Non-invasive brain stimulation in schizophrenia: hallucinations and negative symptoms]

New approaches are needed in the treatment of characteristic symptoms of schizophrenia such as hallucinations and negative symptoms. Non-invasive brain stimulation can make a useful contribution.<br/> AIM: To discuss the published evidence regarding efficacy and safety of repetitive transcranial magnetic stimulation (rtms) and transcranial direct current stimulation (tdcs) when used in the treatment of auditory verbal hallucinations and negative symptoms.<br/> METHOD: We review and discuss recent meta-analyses and we analyse relevant factors.<br/> RESULTS: On average, when compared to sham-stimulation, rtms was found to have a significant effect on hallucinations and negative symptoms. Nevertheless, the results of some studies were variable and some studies did not report any improvement. There are indications that some factors such as age and distance between scalp and cortex may influence efficiency. There were only a few studies relating to the use of tdcs and none of these reported a clear effect.<br/> CONCLUSION: There is reasonable evidence that rtms is an efficient treatment for hallucinations and negative symptoms, although some variable results have been reported. There is insufficient evidence for conclusions to be drawn about the efficacy of tdcs for the treatment of hallucinations and negative symptoms. However, both simulation methods are safe and largely without side-effects.

[Brain stimulation: the most direct form of neurostimulation]

BACKGROUND

Brain stimulation is the most direct form of neuromodulation. Direct brain stimulation is an older procedure that has taken various forms, but 'non-invasive brain stimulation' is a more recent development.

AIM

To provide an overview of the current arsenal of non-invasive brain stimulation techniques.

METHOD

We discuss the underlying principles, the pros and cons, and the applicability of non-invasive brain stimulation in experimental research and treatment of neuropsychiatric disorders.

RESULTS

Non-invasive brain stimulation is a direct form of neuromodulation, which is not invasive, harmful or painful. Its effects are in principle temporary, which makes the technique suitable for experimental research. At the same time, temporary effects can have lasting clinical consequences, if they target neuroplasticity to aid rehabilitation or alleviate symptoms.

CONCLUSION

Whereas the value of non-invasive brain stimulation for research purposes is undisputed, its efficacy and value as a treatment for neuropsychiatric disorders are still being debated. Nevertheless, the accumulated evidence about the clinical efficacy of the treatment for certain disorders is sufficiently compelling to start thinking about European regulations and standard medical insurance coverage.

The prevalence of visual hallucinations in non-affective psychosis, and the role of perception and attention

BACKGROUND

Little is known about visual hallucinations (VH) in psychosis. We investigated the prevalence and the role of bottom-up and top-down processing in VH. The prevailing view is that VH are probably related to altered top-down processing, rather than to distorted bottom-up processing. Conversely, VH in Parkinson's disease are associated with impaired visual perception and attention, as proposed by the Perception and Attention Deficit (PAD) model. Auditory hallucinations (AH) in psychosis, however, are thought to be related to increased attention.

METHOD

Our retrospective database study included 1119 patients with non-affective psychosis and 586 controls. The Community Assessment of Psychic Experiences established the VH rate. Scores on visual perception tests [Degraded Facial Affect Recognition (DFAR), Benton Facial Recognition Task] and attention tests [Response Set-shifting Task, Continuous Performance Test-HQ (CPT-HQ)] were compared between 75 VH patients, 706 non-VH patients and 485 non-VH controls.

RESULTS

The lifetime VH rate was 37%. The patient groups performed similarly on cognitive tasks; both groups showed worse perception (DFAR) than controls. Non-VH patients showed worse attention (CPT-HQ) than controls, whereas VH patients did not perform differently.

CONCLUSIONS

We did not find significant VH-related impairments in bottom-up processing or direct top-down alterations. However, the results suggest a relatively spared attentional performance in VH patients, whereas face perception and processing speed were equally impaired in both patient groups relative to controls. This would match better with the increased attention hypothesis than with the PAD model. Our finding that VH frequently co-occur with AH may support an increased attention-induced 'hallucination proneness'.

Self-related networks and negative symptoms in psychotic disorders

Objective

Two factors of negative symptoms in schizophrenia have been consistently described based on factor analysis, “expressive deficits” and “social amotivation”. We aimed to investigate the putatively differential involvement of self-related networks, as measured with BOLD fMRI during a self-evaluation task, in two dimensions of negative symptoms in schizophrenia (reduced expression and social amotivation).

Method

Forty-five patients with a diagnosis of schizophrenia participated in an fMRI study in which they performed a self-evaluation task. The task comprised a self-reflection, close other-reflection, and a semantic (baseline) condition. We compared correlates of Expressive versus Social amotivation factors (summed items from the PANSS interview) for the contrasts self-baseline and self-other. Significance threshold was set at P < 0.05 family-wise error (FEW) corrected.

Results

Social amotivation correlated significantly with self-evaluation vs. baseline in right and left ACC, and in the sulcus of frontal lateral lobe between inferior frontal triangularis and middle frontal gyrus. This was also significant, but less pronounced, in the direct comparison of social amotivation vs. expressive deficits scores (for the self-baseline contrast). No activation differences survived critical thresholds for the self-other contrast.

Conclusion

Differential neural correlates for the two dimensions of negative symptoms support the validity of this distinction based on factor analyses. Intact functioning of brain circuitry for self-referential processing may be of relevance to actively seek social interaction.

Disclosure of interest

The author has not supplied his declaration of competing interest.

[Metacognition in psychotic disorders: from concepts to intervention]

BACKGROUND

Persons with a psychotic disorder commonly experience difficulties with what is considered to be metacognitive capacity. In this article we discuss several definitions of this concept, the measurement instruments involved and the clinical interventions that target this concept.

AIM

To present a review of various frequently used definitions of metacognition and related concepts and to describe the measurement instruments involved and the treatment options available for improving the metacognitive capacity of persons with a psychotic disorder.

METHOD

We present an overview of several definitions of metacognition in psychotic disorders and we discuss frequently used measurement instruments and treatment options. The article focuses on recent developments in a model devised by Semerari et al. The measurement instrument involved (Metacognition Assessment Scale - A) is discussed in terms of it being an addition to existing methods.

RESULTS

On the basis of the literature it appears that metacognition and related concepts are measurable constructs, although definitions and instruments vary considerably. The new conceptualisation of social information processing also leads to the development of a new form of psychotherapy that aims to help patients suffering from psychotic disorders to improve metacognitive capacity.

CONCLUSION

There seems to be evidence that metacognitive abilities are a possible target for treatment, but further research is needed.

Investigating distinct and common abnormalities of resting-state functional connectivity in depression, anxiety, and their comorbid states

Depression and anxiety disorders are highly comorbid and share neurobiological characteristics. However, this is usually not explicitly addressed in studies on intrinsic brain functioning in these disorders. Contrary to previous resting-state reports on small, monodiagnostic subsets of the current sample, we investigated resting-state functional connectivity (RSFC) in medication-free patients with depression, anxiety, comorbid depression and anxiety, and a healthy control group. RSFC was investigated in 140 medication-free subjects: 37 major depressive disorder patients (MDD), 30 patients with one or more anxiety disorders (ANX), 25 patients with MDD and one or more anxiety disorders (COM), and 48 healthy controls (HC). RSFC networks were calculated using a probabilistic independent component analysis. Using a dual regression approach, individuals׳ timecourses were extracted and regressed to obtain subjects-specific spatial maps, which were used for group comparisons in four networks of interest (limbic, default mode, salience and sensory-motor networks). When compared to HC, the COM group showed increased RSFC of the limbic network with a cluster containing the bilateral precuneus, intracalcarine cortex, lingual gyrus, and posterior cingulate, and with a cluster including the right precentral gyrus, inferior frontal gyrus, and middle frontal gyrus. This effect was specific for comorbid depression and anxiety. No abnormal RSFC of other networks or in the MDD and ANX groups was observed. No association was found between strength of RSFC and symptom severity. These results indicate that altered RSFC of cortical regions with a limbic network could be specific for comorbid depression and anxiety.

Differential effects of antipsychotic drugs on insight in first episode schizophrenia: Data from the European First-Episode Schizophrenia Trial (EUFEST)

Although antipsychotics are widely prescribed, their effect of on improving poor illness insight in schizophrenia has seldom been investigated and therefore remains uncertain. This paper examines the effects of low dose haloperidol, amisulpride, olanzapine, quetiapine, and ziprasidone on insight in first-episode schizophrenia, schizoaffective disorder, or schizophreniform disorder. The effects of five antipsychotic drugs in first episode psychosis on insight were compared in a large scale open randomized controlled trial conducted in 14 European countries: the European First-Episode Schizophrenia Trial (EUFEST). Patients with at least minimal impairments in insight were included in the present study (n=455). Insight was assessed with item G12 of the Positive and Negative Syndrome Scale (PANSS), administered at baseline and at 1, 3, 6, 9, and 12 months after randomization. The use of antipsychotics was associated with clear improvements in insight over and above improvements in other symptoms. This effect was most pronounced in the first three months of treatment, with quetiapine being significantly less effective than other drugs. Effects of spontaneous improvement cannot be ruled out due to the lack of a placebo control group, although such a large spontaneous improvement of insight would seem unlikely.

Efficacy of bilateral repetitive transcranial magnetic stimulation for negative symptoms of schizophrenia: results of a multicenter double-blind randomized controlled trial

BACKGROUND

Few studies have investigated the efficacy of repetitive transcranial magnetic stimulation (rTMS) treatment for negative symptoms of schizophrenia, reporting inconsistent results. We aimed to investigate whether 10 Hz stimulation of the bilateral dorsolateral prefrontal cortex during 3 weeks enhances treatment effects.

METHOD

A multicenter double-blind randomized controlled trial was performed in 32 patients with schizophrenia or schizo-affective disorder, and moderate to severe negative symptoms [Positive and Negative Syndrome Scale (PANSS) negative subscale ⩾15]. Patients were randomized to a 3-week course of active or sham rTMS. Primary outcome was severity of negative symptoms as measured with the Scale for the Assessment of Negative Symptoms (SANS) and the PANSS negative symptom score. Secondary outcome measures included cognition, insight, quality of life and mood. Subjects were followed up at 4 weeks and at 3 months. For analysis of the data a mixed-effects linear model was used.

RESULTS

A significant improvement of the SANS in the active group compared with sham up to 3 months follow-up (p = 0.03) was found. The PANSS negative symptom scores did not show a significant change (p = 0.19). Of the cognitive tests, only one showed a significant improvement after rTMS as compared with sham. Finally, a significant change of insight was found with better scores in the treatment group.

CONCLUSIONS

Bilateral 10 Hz prefrontal rTMS reduced negative symptoms, as measured with the SANS. More studies are needed to investigate optimal parameters for rTMS, the cognitive effects and the neural basis.

Insight change in psychosis: relationship with neurocognition, social cognition, clinical symptoms and phase of illness

OBJECTIVE

Impaired insight is an important and prevalent symptom of psychosis. It remains unclear whether cognitive disturbances hamper improvements in insight. We investigated the neurocognitive, social cognitive, and clinical correlates of changes in insight.

METHOD

One hundred and fifty-four patients with a psychotic disorder were assessed at baseline (T0 ) and after three years (T3 ) with the Birchwood Insight Scale, the Positive And Negative Syndrome Scale, measures of neurocognition and social cognition. Linear regression analyses were conducted to examine to what extend neurocognition, social cognition, clinical symptoms and phase of illness could uniquely predict insight change. Subsequently, changes in these factors were related to insight change.

RESULTS

Better neurocognitive performance and fewer clinical symptoms at baseline explained insight improvements. The additional effect of clinical symptoms over and above the contribution of neurocognition was significant. Together, these factors explained 10% of the variance. Social cognition and phase of illness could not predict insight change. Changes in clinical symptoms, but not changes in neurocognitive performance were associated with insight change.

CONCLUSION

Neurocognitive abilities may predict, in part, the development of insight in psychosis.

Cognitive subtypes in non-affected siblings of schizophrenia patients: characteristics and profile congruency with affected family members

BACKGROUND

Although cognitive subtypes have been suggested in schizophrenia patients, similar analyses have not been carried out in their non-affected siblings. Subtype classification may provide more insight into genetically driven variation in cognitive function. We investigated cognitive subtypes in siblings.

METHOD

Cluster analyses were performed in 654 non-affected siblings, on a cognitive battery that included tests of attention, intellectual function and episodic memory. Resulting subtypes in the siblings were analyzed for cognitive, demographic and clinical characteristics and compared with those of their probands.

RESULTS

Three sibling subtypes of cognitive function were distinguished: 'normal', 'mixed' and 'impaired'. Normal profile siblings (n = 192) were unimpaired on cognitive tests, in contrast to their proband (n = 184). Mixed profile siblings (n = 228) and their probands (n = 222) had a more similar performance pattern. Impaired profile siblings had poorer functional outcomes (n = 234) and their profile was almost identical to that of their proband (n = 223). Probands with cognitively impaired siblings could be distinguished from other schizophrenia patients by their own cognitive performance. They also had poorer clinical characteristics, including achievement of symptomatic remission.

CONCLUSIONS

Unaffected siblings of patients with schizophrenia are heterogeneous with respect to cognitive function. The poorer the cognitive profile of the sibling, the higher the level of correspondence with the proband. The sibling's cognitive subtype was predictive for disease course in the proband. Distinguishing cognitive subtypes of unaffected siblings may be of relevance for genetic studies.

[Brain activation as endophenotype for investigating genetics of depression]

BACKGROUND

Many factors are involved in the pathogenesis of depression. This article provides an overview of the results given in the thesis entitled 'Linking Depression', in which some putative underlying neurobiological and genetic mechanisms of depression are examined.

AIM

To gain more insight in brain activity as endophenotype for depression.

METHOD

As part of the Netherlands Study of Depression and Anxiety (nesda), 301 people, including patients with depression and/or anxiety and healthy volunteers, underwent functional magnetic resonance imaging (fmri) and genotyping.

RESULTS

During the processing of negative emotions, patients with depression showed a pattern of heightened limbic activation but less prefrontal activation. The same pattern, but in reverse, was seen during the processing of positive emotions. We showed that the disc1, comt and npy genes were associated with brain activation patterns comparable to those seen in patients with depression. In addition, in cases of depression, there was a different kind of relationship between these genes and brain activation.

CONCLUSION

Depression is characterised by the disturbed processing not only of negative emotions but also of positive emotions. In addition, the studies we describe contribute to our insight into the neurobiology of depression and relevant genetic influences because the results demonstrate that depression alters the relationship between genes and brain activation.