Cognitive impairment in schizophrenia: profile, course, and neurobiological determinants

CCRT and aerobic exercise: a randomised controlled study of processing speed, cognitive flexibility, and serum BDNF expression in schizophrenia

Computerised cognitive remediation therapy (CCRT) and aerobic exercise are often used to rehabilitate social functioning in patients with schizophrenia. However, there is limited knowledge regarding the effects of CCRT combined with aerobic exercise on cognitive function and brain-derived neurotrophic factor (BDNF) levels in patients with schizophrenia and cognitive impairment. Ninety-six patients with schizophrenia and cognitive impairment were included in this study and randomly divided into control, aerobic exercise (AE), and CCRT combined with aerobic exercise (CAE) groups. Changes in processing speed and cognitive flexibility at week 8 were evaluated as primary and secondary cognitive outcomes using the Trail Making Test: Part A, the Brief Assessment of Cognition in Schizophrenia: Symbol Coding Test, and the Stroop Colour-Word Test. Positive and Negative Syndrome Scale (PANSS) scores and serum BDNF expression were determined as other secondary outcomes. The CAE group showed significantly better performance in terms of changes in processing speed and cognitive flexibility than the control and AE groups at week 8 (p < 0.05); however, no significant improvements in processing speed and cognitive flexibility were found between the control and AE groups. The CAE group showed significant improvements in the PANSS negative symptoms than the control group at week 8 (p < 0.05), but the AE group showed no significant difference in the changes of PANSS negative symptoms when compared with the other two groups. The CAE group and AE group showed a greater increase in serum BDNF levels than the control group (p < 0.01), but there was no significant difference in serum BDNF expression between the CAE group and AE group. In conclusion, 8-week CCRT combined with aerobic exercise may improve some cognitive performance and negative symptoms in patients with schizophrenia. Aerobic exercise may have an immediate effect on serum BDNF levels rather than cognitive function.

Screening for cognitive impairment in non-affective psychoses: A comparison between the SCIP and the MoCA

BACKGROUND

Neuropsychological performance has a strong impact on real-life functioning and clinical outcomes in psychosis. However, conducting lengthy cognitive assessments may not be feasible in routine clinical practice. Brief, reliable and cost-effective tools are highly needed, but few studies are available to guide clinician choice.

METHODS

The purpose of this study was to compare the performance of two widely used, short instruments: the Screen for Cognitive Impairment in Psychiatry (SCIP) and the Montreal Cognitive Assessment (MoCA). These instruments were validated in a sample of patients with psychotic disorders and healthy controls, using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and other instruments to assess executive functions, as comparators.

RESULTS

Patients fared worse than controls across almost all cognitive domains, with effect sizes ranging from 0 (MoCA naming) to 2.08 (SCIP total). Receiver Operator Curve analysis of patient and control performance suggested a better convergent validity for the SCIP (total score AUC: 0.85; 95%CI: 0.79-0.90; Se: 76%, Sp: 83%, PPV: 85%, NPV: 73%) than the MoCA (AUC: 0.78; 95%CI: 0.72-0.85; Se: 69%, Sp: 76%, PPV: 78.7%, NPV 66%).

CONCLUSIONS

The Screen for Cognitive Impairment in Psychiatry seems to be a more sensitive and specific screening tool than the MoCA to identify cognitive impairment among patients with psychotic disorders.

Uncovering complex central autonomic networks at rest: a functional magnetic resonance imaging study on complex cardiovascular oscillations

This study aims to uncover brain areas that are functionally linked to complex cardiovascular oscillations in resting-state conditions. Multi-session functional magnetic resonance imaging (fMRI) and cardiovascular data were gathered from 34 healthy volunteers recruited within the human connectome project (the '100-unrelated subjects' release). Group-wise multi-level fMRI analyses in conjunction with complex instantaneous heartbeat correlates (entropy and Lyapunov exponent) revealed the existence of a specialized brain network, i.e. a complex central autonomic network (CCAN), reflecting what we refer to as complex autonomic control of the heart. Our results reveal CCAN areas comprised the paracingulate and cingulate gyri, temporal gyrus, frontal orbital cortex, planum temporale, temporal fusiform, superior and middle frontal gyri, lateral occipital cortex, angular gyrus, precuneous cortex, frontal pole, intracalcarine and supracalcarine cortices, parahippocampal gyrus and left hippocampus. The CCAN visible at rest does not include the insular cortex, thalamus, putamen, amygdala and right caudate, which are classical CAN regions peculiar to sympatho-vagal control. Our results also suggest that the CCAN is mainly involved in complex vagal control mechanisms, with possible links with emotional processing networks.

Functional near infra-red spectroscopy (fNIRS) in schizophrenia: A review

The research on the alterations in functional connectivity in schizophrenia has been facilitated by development of an array of functional neuroimaging techniques. Functional Near Infra Red Spectroscopy (fNIRS) is a novel diffuse optical neuromonitring method with its own advantages and limitations. The advantages of fNIRS have made it to be frequently used as a research tool by medical community in different settings. In fNIRS the property of haemoglobin to absorb near infrared light is used to measure brain activity. It provides the indirect measurement of the neuronal activity in the areas of interest. The advantage of fNIRS being less restrictive has made it to be used more commonly in the research of psychiatric disorders in general, schizophrenia in particular. The fNIRS studies on patients with schizophrenia have shown haemodynamic hypo activation primarily in the prefrontal cortex during various cognitive tasks. In this review, initially we have briefly explained the basic principles of fNIRS followed by detailed review of fNIRS findings in patients with schizophrenia.

Acoustic prepulse inhibition: one ear is better than two, but why and when?

We examined whether monaural prepulses produce more prepulse inhibition (PPI) because they might be more attention capturing (unambiguous to locate) than binaural prepulses. Monaural and binaural PPI was tested under normal and verbal and visuospatial attention manipulation conditions in 55 healthy men, including 29 meditators. Attention manipulations abolished monaural PPI superiority, similarly in meditators and meditation-naïve individuals, and this was most strongly evident for right ear PPI under visuospatial attention manipulation. Meditators performed better than meditation-naïve individuals on attention tasks (verbal: more targets detected; visuospatial: faster reaction time). Spatial attention processes contribute to monaural PPI, particularly with the right ear. Better attentional performance, with similar attentional modulation of PPI, may indicate a stronger attentional capacity in meditators, relative to meditation-naïve individuals.

Clinical correlates of parametric digit-symbol substitution test in schizophrenia

Processing speed deficit, ascertained by digit-symbol substitution test (DSST), is considered as a fundamental impairment in schizophrenia. Clinical correlates of processing speed abnormalities, especially using the parametric version of DSST is yet to be evaluated comprehensively. In this study, we examined schizophrenia patients (N=66) and demographically matched healthy controls (N=72) using computer-administered parametric DSST (pDSST) with fixed (pDSSTF) as well as random (pDSSTR) conditions and analysed the relationship between pDSST performance and clinical symptoms. Psychopathology was assessed using Scale for Assessment of Positive Symptoms (SAPS)/Negative Symptoms (SANS) with good inter-rater reliability. In comparison with healthy controls, patients demonstrated significantly lesser number of correct responses (CN) in pDSSTF (t=8.0; p<0.001) and pDSSTR (t=7.8; p<0.001) as well as significantly prolonged reaction time in pDSSTF (t=7.1; p<0.001) and pDSSTR (t=7.0; p<0.001). The difference in CN between pDSSTF and pDSSTR [ΔCN] was significantly lesser in patients than healthy controls (t=2.61; p=0.01). The pDSST reaction time had significant positive correlation with negative syndrome scores as well as bizarre behaviour score. Significantly greater processing speed deficits in pDSST suggest potential relational memory/visual scanning abnormalities in schizophrenia. Furthermore, pDSST deficits demonstrated a significant association with the psychopathology, especially with the various negative symptoms and bizarre behaviour.

Prenatal maternal factors in the development of cognitive impairments in the offspring

Different environmental factors acting during sensitive prenatal periods can have a negative impact on neurodevelopment and predispose the individual to the development of various psychiatric conditions that often share cognitive impairments as a common component. As cognitive symptoms remain one of the most challenging and resistant aspects of mental illness to be treated pharmacologically, it is important to investigate the mechanisms underlying such cognitive deficits, with particular focus on the impact of early life adverse events that predispose the individual to mental disorders. Multiple clinical studies have, in fact, repeatedly confirmed that prenatal maternal factors, such as infection, stress or malnutrition, are pivotal in shaping behavioral and cognitive functions of the offspring, and in the past decade many preclinical studies have investigated this hypothesis. The purpose of this review is to describe recent preclinical studies aimed at dissecting the relative impact of various prenatal maternal factors on the development of cognitive impairments in offspring, focusing on animal models of prenatal stress and prenatal infection. These recent studies point to the pivotal role of prenatal stressful experiences in shaping memory and learning functions associated with specific brain structures, such as the hippocampus and the prefrontal cortex. More importantly, such experimental evidence suggests that different insults converge on similar downstream functional targets, such as cognition, which may therefore represent an endophenotype for several pathological conditions. Future studies should thus focus on investigating the mechanisms contributing to the convergent action of different prenatal insults in order to identify targets for novel therapeutic intervention.

Schizophrenia and frontotemporal dementia: shared causation?

The relationship between specific genes and particular diseases in neuropsychiatry is unclear, and newer studies focus on shared domains of neurobiological and cognitive pathology across different disorders. This paper reviews the evidence for an association between schizophrenia and frontotemporal dementia, including symptom similarity, familial co-morbidity, and neuroanatomical changes. Genetic as well as epigenetic findings from both schizophrenia and frontotemporal dementia are also discussed. As a result, we introduce the hypothesis of a shared susceptibility for certain subgroups of schizophrenia and frontotemporal dementia. This common causation may involve the same gene(s) at different stages of life: early in schizophrenia and late in frontotemporal dementia. Additionally, we provide a rationale for future research that should emphasize both genetic and cognitive parallels between certain forms of schizophrenia and frontotemporal dementia in a synergistic, coordinated way, placing both in the context of aberrant lateralization patterns.

Management of frontotemporal dementia in mental health and multidisciplinary settings

Diagnosis of frontotemporal dementia (FTD) in the mental health setting and issues pertaining to longitudinal care of this population in a specialist clinic are reviewed. FTD is often misdiagnosed as a psychiatric disorder, most commonly as a mood disorder. FTD has features that overlap with those of major depression, mania, obsessive-compulsive disorder and schizophrenia. We describe these features and how to differentiate FTD from these psychiatric disorders. This paper also describes practical issues in the management of FTD, specifically the issues that clinicians, patients and their families face in managing this disease. Areas of clinical care along the continuum are explored; FTD care involves collaborative management of symptoms and disability, and assisting patients and families in adapting to the disease.

Functional outcomes, functional capacity, and cognitive impairment in schizotypal personality disorder

BACKGROUND

Individuals with schizotypal personality disorder (SPD) exhibit impaired cognitive functioning in a pattern similar to that found in schizophrenia; less clear is the extent to which these individuals also share schizophrenia patients' impairments in functional capacity and real-world functioning.

METHOD

We evaluated 46 SPD patients, as well as 38 individuals with avoidant personality disorder (AvPD) and 55 healthy controls (HC) on: cognitive functioning, real-world functioning (employment and residential status), and functional capacity (indexed by the UPSA, a performance-based skills assessment).

RESULTS

We found that individuals with SPD exhibited worse performance on both the cognitive battery and the UPSA than the other groups; they were also less likely to be employed and to be living independently. Additionally, cognitive and UPSA performance in the SPD group was intercorrelated to a degree comparable to what has been found in schizophrenia, and this relationship was not present in the AvPD group. Finally, real-world functioning was related to UPSA performance for both patient groups.

CONCLUSIONS

SPD patients exhibit impaired real-world functioning suggesting that these deficits extend across the schizophrenia spectrum. In addition, there is supportive evidence for the validity and importance of performance-based measures such as the UPSA to predict everyday outcomes across the schizophrenia spectrum.

Basic disturbances of information processing in psychosis prediction

The basic symptoms (BS) approach provides a valid instrument in predicting psychosis onset and represents moreover a significant heuristic framework for research. The term "basic symptoms" denotes subtle changes of cognition and perception in the earliest and prodromal stages of psychosis development. BS are thought to correspond to disturbances of neural information processing. Following the heuristic implications of the BS approach, the present paper aims at exploring disturbances of information processing, revealed by functional magnetic resonance imaging (fMRI) and electro-encephalographic as characteristics of the at-risk state of psychosis. Furthermore, since high-risk studies employing ultra-high-risk criteria revealed non-conversion rates commonly exceeding 50%, thus warranting approaches that increase specificity, the potential contribution of neural information processing disturbances to psychosis prediction is reviewed. In summary, the at-risk state seems to be associated with information processing disturbances. Moreover, fMRI investigations suggested that disturbances of language processing domains might be a characteristic of the prodromal state. Neurophysiological studies revealed that disturbances of sensory processing may assist psychosis prediction in allowing for a quantification of risk in terms of magnitude and time. The latter finding represents a significant advancement since an estimation of the time to event has not yet been achieved by clinical approaches. Some evidence suggests a close relationship between self-experienced BS and neural information processing. With regard to future research, the relationship between neural information processing disturbances and different clinical risk concepts warrants further investigations. Thereby, a possible time sequence in the prodromal phase might be of particular interest.

Cognitive deficits, obesity and disability in schizophrenia

Despite 50 years of pharmacological and psychosocial interventions schizophrenia remains one of the leading causes of disability. The inability to function in everyday settings includes deficits in performance of social, occupational, and independent living activities. Schizophrenia is also a life-shortening illness, caused mainly by poor physical health and its complications. Dysfunctional lifestyles including sedentary behavior and lack of physical activity prevail, while treatment with adipogenic antipsychotic medication interacts with poor performance in screening, monitoring, and intervention that result in shortening of life expectancies by 25–30 years. Disability interferes with self-care and medical care, further worsening physical health to produce a vicious cycle of disability. Further, the neurobiological impact of obesity on brain functioning is substantial and relevant to schizophrenia. Decision making deficits that lead to choices resulting in obesity themselves have neurobiological determinants. Simultaneous treatment of cognitive deficits and related deficits in functional skills, ubiquitous determinants of everyday functioning in schizophrenia, and targeted interventions aimed at poor physical health, especially obesity and associated comorbidities, may lead to additive or even interactive gains in everyday functioning in patients with schizophrenia not previously realized with other interventions.