Renata Smieskova

Cognitive Functioning in Prodromal Psychosis: A Meta-analysis

CONTEXT A substantial proportion of people at clinical high risk (HR) of psychosis will develop a psychotic disorder over time. Cognitive deficits may predate the onset of psychosis and may be useful as markers of increased vulnerability to illness. OBJECTIVE To quantitatively examine the cognitive functioning in subjects at HR in the literature to date. DATA SOURCES Electronic databases were searched until January 2011. All studies reporting cognitive performance in HR subjects were retrieved. STUDY SELECTION Nineteen studies met the inclusion criteria, comprising a total of 1188 HR subjects and 1029 controls. DATA EXTRACTION Neurocognitive functioning and social cognition as well as demographic, clinical, and methodological variables were extracted from each publication or obtained directly from its authors. DATA SYNTHESIS Subjects at HR were impaired relative to controls on tests of general intelligence, executive function, verbal and visual memory, verbal fluency, attention and working memory, and social cognition. Processing speed domain was also affected, although the difference was not statistically significant. Later transition to psychosis was associated with even more marked deficits in the verbal fluency and memory domains. The studies included reported relatively homogeneous findings. There was no publication bias and a sensitivity analysis confirmed the robustness of the core results. CONCLUSIONS The HR state for psychosis is associated with significant and widespread impairments in neurocognitive functioning and social cognition. Subsequent transition to psychosis is particularly associated with deficits in verbal fluency and memory functioning.

Progressive brain changes in schizophrenia related to antipsychotic treatment? A meta-analysis of longitudinal MRI studies

Context Antipsychotic treatment is the first-line treatment option for schizophrenia. Individual studies suggested they can significantly affect brain structure and account for progressive brain changes observed during the illness. Objectives To quantitatively examine the effect of antipsychotics as compared to illness related factors on progressive brain changes in schizophrenia. Data sources Electronic databases were searched until April 2012. All magnetic resonance imaging studies reporting progressive brain changes in schizophrenia subjects and antipsychotic exposure were retrieved. Study selection 30 longitudinal MRI studies with antipsychotic administration in schizophrenia patients met the inclusion criteria. Data extraction Brain volumes before and after antipsychotic exposure, duration of illness, severity of psychotic symptoms as well as demographic, clinical, and methodological variables were extracted from each publication, or obtained directly from its authors. Data synthesis The overall sample was of 1046 schizophrenia patients and 780 controls for a median duration of follow-up of 72.4 weeks. At baseline, patients showed significant whole brain volume reductions and enlarged lateral ventricle (LV) volumes compared to controls. No baseline volumetric abnormalities were detected in the gray matter volumes (GMV), white matter volumes, cerebrospinal fluid and caudate nucleus. Longitudinally, there were progressive GMV decreases and LV enlargements in patients but not in controls. The GMV decreases were inversely correlated with cumulative exposure to antipsychotic treatments, while no effects were observed for duration of illness or illness severity. Conclusions Schizophrenia is characterized by progressive gray matter volume decreases and lateral ventricular volume increases. Some of these neuroanatomical alterations may be associated with antipsychotic treatment.

Neuroimaging predictors of transition to psychosis : a systematic review and meta-analysis

OBJECTIVES In early stage psychosis research the identification of neurobiological correlates of vulnerability to schizophrenia is an important hurdle. METHODS We systematically reviewed the neuroimaging publications on high-risk subjects with subsequent transition to psychosis (HR-T) and conducted a meta-analysis calculating the effect size Cohens d. RESULTS Out of 30 identified studies 25 met the inclusion criteria. Structural (s)MRI studies showed small to medium effect sizes of decreased prefrontal, cingulate, insular and cerebellar gray matter volume in HR-T compared to high-risk subjects without transition (HR-NT). Meta-analysis revealed relatively larger whole brain volumes in HR-T compared to HR-NT subjects (mean Cohens d 0.36, 95% CI 0.27-0. 46). Compared to HR-NT, HR-T subjects showed in functional imaging studies reduced brain activation in prefrontal cortex, reduced neuronal density, and increased membrane turnover in frontal and cingulate cortex with medium to large effect sizes. CONCLUSIONS Despite methodological differences between studies, structural and neurochemical abnormalities in prefrontal, anterior cingulate, medial temporal and cerebellar cortex might be predictive for development of psychosis within HR subjects.

The Effects of Antipsychotics on the Brain: What Have We Learnt from Structural Imaging of Schizophrenia? – A Systematic Review

Despite a large number of neuroimaging studies in schizophrenia reporting subtle brain abnormalities, we do not know to what extent such abnormalities reflect the effects of antipsychotic treatment on brain structure. We therefore systematically reviewed cross-sectional and follow-up structural brain imaging studies of patients with schizophrenia treated with antipsychotics. 30 magnetic resonance imaging (MRI) studies were identified, 24 of them being longitudinal and six cross-sectional structural imaging studies. In patients with schizophrenia treated with antipsychotics, reduced gray matter volume was described, particularly in the frontal and temporal lobes. Structural neuroimaging studies indicate that treatment with typical as well as atypical antipsychotics may affect regional gray matter (GM) volume. In particular, typical antipsychotics led to increased gray matter volume of the basal ganglia, while atypical antipsychotics reversed this effect after switching. Atypical antipsychotics, however, seem to have no effect on basal ganglia structure.

Brain Connectivity Abnormalities Predating the Onset of Psychosis Correlation With the Effect of Medication

IMPORTANCE Brain imaging studies have identified robust changes in brain structure and function during the development of psychosis, but the contribution of abnormal brain connectivity to the onset of psychosis is unclear. Furthermore, antipsychotic treatment can modulate brain activity and functional connectivity during cognitive tasks. OBJECTIVES To investigate whether dysfunctional brain connectivity during working memory (WM) predates the onset of psychosis and whether connectivity parameters are related to antipsychotic treatment. DESIGN Dynamic causal modeling study of functional magnetic resonance imaging data. SETTING Participants were recruited from the specialized clinic for the early detection of psychosis at the Department of Psychiatry, University of Basel, Basel, Switzerland. PARTICIPANTS Seventeen participants with an at-risk mental state (mean [SD] age, 25.24 [6.3] years), 21 individuals with first-episode psychosis (mean [SD] age, 28.57 [7.2] years), and 20 healthy controls (mean [SD] age, 26.5 [4] years). MAIN OUTCOME AND MEASURE Functional magnetic resonance imaging data were recorded while participants performed an N-back WM task. Functional interactions among brain regions involved in WM, in particular between frontal and parietal brain regions, were characterized using dynamic causal modeling. Bayesian model selection was performed to evaluate the likelihood of alternative WM network architectures across groups, whereas bayesian model averaging was used to examine group differences in connection strengths. RESULTS We observed a progressive reduction in WM-induced modulation of connectivity from the middle frontal gyrus to the superior parietal lobule in the right hemisphere in healthy controls, at-risk mental state participants, and first-episode psychosis patients. Notably, the abnormal modulation of connectivity in first-episode psychosis patients was normalized by treatment with antipsychotics. CONCLUSIONS AND RELEVANCE Our findings suggest that the vulnerability to psychosis is associated with a progressive failure of functional integration of brain regions involved in WM processes, including visual encoding and rule updating, and that treatment with antipsychotics may have the potential to counteract this.

Detecting the Psychosis Prodrome Across High-Risk Populations Using Neuroanatomical Biomarkers

To date, the MRI-based individualized prediction of psychosis has only been demonstrated in single-site studies. It remains unclear if MRI biomarkers generalize across different centers and MR scanners and represent accurate surrogates of the risk for developing this devastating illness. Therefore, we assessed whether a MRI-based prediction system identified patients with a later disease transition among 73 clinically defined high-risk persons recruited at two different early recognition centers. Prognostic performance was measured using cross-validation, independent test validation, and Kaplan-Meier survival analysis. Transition outcomes were correctly predicted in 80% of test cases (sensitivity: 76%, specificity: 85%, positive likelihood ratio: 5.1). Thus, given a 54-month transition risk of 45% across both centers, MRI-based predictors provided a 36%-increase of prognostic certainty. After stratifying individuals into low-, intermediate-, and high-risk groups using the predictors decision score, the high- vs low-risk groups had median psychosis-free survival times of 5 vs 51 months and transition rates of 88% vs 8%. The predictors decision function involved gray matter volume alterations in prefrontal, perisylvian, and subcortical structures. Our results support the existence of a cross-center neuroanatomical signature of emerging psychosis enabling individualized risk staging across different high-risk populations. Supplementary results revealed that (1) potentially confounding between-site differences were effectively mitigated using statistical correction methods, and (2) the detection of the prodromal signature considerably depended on the available sample sizes. These observations pave the way for future multicenter studies, which may ultimately facilitate the neurobiological refinement of risk criteria and personalized preventive therapies based on individualized risk profiling tools.

BDNF Val66Met polymorphism and hippocampal volume in neuropsychiatric disorders: A systematic review and meta-analysis.

BACKGROUND Brain-derived neurotrophic factor (BDNF) is a neurotrophin involved in neurogenesis and synaptic plasticity in the central nervous system, especially in the hippocampus, and has been implicated in the pathophysiology of several neuropsychiatric disorders. Its Val66Met polymorphism (refSNP Cluster Report: rs6265) is a functionally relevant single nucleotide polymorphism affecting the secretion of BDNF and is implicated in differences in hippocampal volumes. METHODS This is a systematic meta-analytical review of findings from imaging genetic studies on the impact of the rs6265 SNP on hippocampal volumes in neuropsychiatric patients with major depressive disorder, anxiety, bipolar disorder or schizophrenia. RESULTS The overall sample size of 18 independent clinical cohorts comprised 1695 patients. Our results indicated no significant association of left (Hedges g=0.08, p=0.12), right (g=0.07, p=0.22) or bilateral (g=0.07, p=0.16) hippocampal volumes with BDNF rs6265 in neuropsychiatric patients. There was no evidence for a publication bias or any demographic, clinical, or methodological moderating effects. Both Val/Val homozygotes (g=0.32, p=0.004) and Met-carriers (g=0.20, p=0.004) from the patient sample had significantly smaller hippocampal volumes than the healthy control sample with the same allele. The magnitude of these effects did not differ between the two genotypes. CONCLUSION This meta-analysis suggests that there is no association between this BDNF polymorphism and hippocampal volumes. For each BDNF genotype, the hippocampal volumes were significantly lower in neuropsychiatric patients than in healthy controls.

Different duration of at‐risk mental state associated with neurofunctional abnormalities. A multimodal imaging study

Objectives: Neurofunctional alterations are correlates of vulnerability to psychosis, as well as of the disorder itself. How these abnormalities relate to different probabilities for later transition to psychosis is unclear. We investigated vulnerability‐ versus disease‐related versus resilience biomarkers of psychosis during working memory (WM) processing in individuals with an at‐risk mental state (ARMS). Experimental design: Patients with “first‐episode psychosis” (FEP, n = 21), short‐term ARMS (ARMS‐ST, n = 17), long‐term ARMS (ARMS‐LT, n = 16), and healthy controls (HC, n = 20) were investigated with an n‐back WM task. We examined functional magnetic resonance imaging (fMRI) and structural magnetic resonance imaging (sMRI) data in conjunction using biological parametric mapping (BPM) toolbox. Principal observations: There were no differences in accuracy, but the FEP and the ARMS‐ST group had longer reaction times compared with the HC and the ARMS‐LT group. With the 2‐back > 0‐back contrast, we found reduced functional activation in ARMS‐ST and FEP compared with the HC group in parietal and middle frontal regions. Relative to ARMS‐LT individuals, FEP patients showed decreased activation in the bilateral inferior frontal gyrus and insula, and in the left prefrontal cortex. Compared with the ARMS‐LT, the ARMS‐ST subjects showed reduced activation in the right inferior frontal gyrus and insula. Reduced insular and prefrontal activation was associated with gray matter volume reduction in the same area in the ARMS‐LT group. Conclusions: These findings suggest that vulnerability to psychosis was associated with neurofunctional alterations in fronto‐temporo‐parietal networks in a WM task. Neurofunctional differences within the ARMS were related to different duration of the prodromal state and resilience factors. Hum Brain Mapp 33:2281–2294, 2012.

Distinguishing Prodromal From First-Episode Psychosis Using Neuroanatomical Single-Subject Pattern Recognition

BACKGROUND The at-risk mental state for psychosis (ARMS) and the first episode of psychosis have been associated with structural brain abnormalities that could aid in the individualized early recognition of psychosis. However, it is unknown whether the development of these brain alterations predates the clinical deterioration of at-risk individuals, or alternatively, whether it parallels the transition to psychosis at the single-subject level. METHODS We evaluated the performance of an magnetic resonance imaging (MRI)-based classification system in classifying disease stages from at-risk individuals with subsequent transition to psychosis (ARMS-T) and patients with first-episode psychosis (FE). Pairwise and multigroup biomarkers were constructed using the structural MRI data of 22 healthy controls (HC), 16 ARMS-T and 23 FE subjects. The performance of these biomarkers was measured in unseen test cases using repeated nested cross-validation. RESULTS The classification accuracies in the HC vs FE, HC vs ARMS-T, and ARMS-T vs FE analyses were 86.7%, 80.7%, and 80.0%, respectively. The neuroanatomical decision functions underlying these discriminative results particularly involved the frontotemporal, cingulate, cerebellar, and subcortical brain structures. CONCLUSIONS Our findings suggest that structural brain alterations accumulate at the onset of psychosis and occur even before transition to psychosis allowing for the single-subject differentiation of the prodromal and first-episode stages of the disease. Pattern regression techniques facilitate an accurate prediction of these structural brain dynamics at the early stage of psychosis, potentially allowing for the early recognition of individuals at risk of developing psychosis.

Do Subjects at Clinical High Risk for Psychosis Differ from those with a Genetic High Risk? – A Systematic Review of Structural and Functional Brain Abnormalities

Introduction: Pre-psychotic and early psychotic characteristics are investigated in the high-risk (HR) populations for psychosis. There are two different approaches based either on hereditary factors (genetic high risk, G-HR) or on the clinically manifested symptoms (clinical high risk, C-HR). Common features are an increased risk for development of psychosis and similar cognitive as well as structural and functional brain abnormalities. Methods: We reviewed the existing literature on longitudinal structural, and on functional imaging studies, which included G-HR and/or C-HR individuals for psychosis, healthy controls (HC) and/or first episode of psychosis (FEP) or schizophrenia patients (SCZ). Results: With respect to structural brain abnormalities, vulnerability to psychosis was associated with deficits in frontal, temporal, and cingulate regions in HR, with additional insular and caudate deficits in C-HR population. Furthermore, C-HR had progressive prefrontal deficits related to the transition to psychosis. With respect to functional brain abnormalities, vulnerability to psychosis was associated with prefrontal, cingulate and middle temporal abnormalities in HR, with additional parietal, superior temporal, and insular abnormalities in C-HR population. Transition-to-psychosis related differences emphasized prefrontal, hippocampal and striatal components, more often detectable in C-HR population. Multimodal studies directly associated psychotic symptoms displayed in altered prefrontal and hippocampal activations with striatal dopamine and thalamic glutamate functions. Conclusion: There is an evidence for similar structural and functional brain abnormalities within the whole HR population, with more pronounced deficits in the C-HR population. The most consistent evidence for abnormality in the prefrontal cortex reported in structural, functional and multimodal studies of HR population may underlie the complexity of higher cognitive functions that are impaired during HR mental state for psychosis.