Association between electroencephalographic modulation, psychotic-like experiences and cognitive performance in the general population.

AIM: An association between deficit of electroencephalographic (EEG) modulation during an odd-ball task and psychotic symptoms has been described in clinical samples, in agreement with the proposed role for altered salience in psychosis. To discard the possible influence of medication, the relationship between psychotic-like experiences and EEG modulation in the general population was explored. METHODS: EEG and psychotic-like experiences were assessed in 194 healthy subjects during a P300 paradigm. EEG modulation was assessed as changes from pre-stimulus to response windows in spectral entropy (SE, a measurement of signal irregularity), median frequency (MF, a quantifier of the frequency distribution of oscillatory activity) and theta, alpha, beta-1, beta-2 and gamma relative power (RP, a summary of the distribution of spectral components). RESULTS: A significant widespread decrease in SE and MF from baseline to response was found, with a significant increase in RP for theta and a decrease for higher frequency bands, supporting an increase in EEG regularity and a slowing of brain oscillations during the response. Furthermore, a significant association was found between SE modulation and distress of negative psychotic-like experiences, as well as between verbal memory and RP modulation for beta-1. Performance in verbal fluency was associated with the increase in theta RP during the response. CONCLUSION: EEG irregularity of healthy subjects decreased at the expense of a larger contribution of theta RP and a decreased contribution of fast frequency bands. Subjects with smaller modulation showed poorer cognitive scores and greater distress of negative psychotic-like experiences.

Clinical, physical, physiological, and cardiovascular risk patterns of adults with schizophrenia: CORTEX-SP study: Characterization of adults with schizophrenia.

Schizophrenia (SP) is a severe mental illness with high rates of premature morbidity and mortality, associated with an unhealthy lifestyle and the side effects of drug treatment. The aims of the study were: 1) to determine some key physical, physiological and biochemical markers of health status, including sleep quality, in adults (42±10 yr) with SP (n=126), 2) to estimate cardiovascular risk (CVR), and 3) to compare all studied variables with a healthy control (HC) population (n=30). Assessment was based on body composition, blood pressure, cardiorespiratory condition, sleep quality with triaxial accelerometry for eight days and biochemical analysis. Participants with SP showed a cardiovascular risk profile including "overweight metabolically abnormal", low cardiorespiratory fitness, and impairment of ventilatory efficiency. Although individuals with SP slept more compared to HC, similar sleep efficiency was shown by both groups, but with significantly higher levels of wake after sleep onset by SP. The assessment of CVR revealed significantly higher values in SP (moderate risk) compared to HC (low risk) regardless of the estimation system. The identification of specific clinical, physical, and physiological CVR profiles in SP illness compared to healthy people strongly suggests targeting a comprehensive approach including non-pharmacological interventions. Clinical Trials.gov identifier, NCT03509597. Date of registration: April 26th, 2018.

Correlates of neurocognitive functions in individuals at ultra-high risk for psychosis - A 6-month follow-up study.

Cognitive deficits are evident at the prodromal phase of psychosis. It has been noted that brain-derived neurotrophic factor (BDNF) is correlated with cognition in both preclinical and clinical studies. However, to our knowledge, no study has evaluated blood BDNF levels and their association with cognitive impairment in individuals at ultra-high risk for psychosis (UHR). We included 13 individuals at UHR and 30 healthy controls (HC) matched by sex, age, and educational level. Plasma BDNF levels were measured at baseline and 6 months. Neurocognitive functions (executive functions, speed of processing, verbal learning and memory, working memory) were examined at 6 months. Regression analyses were conducted to examine the relationship between BDNF levels and cognitive performance. BDNF levels were lower in UHR group than in HC group both at baseline and at 6 months (P = 0.001, and P = 0.007, respectively). There were no associations between plasma BDNF levels and all of the cognitive domains in both groups. Our findings showed that peripheral BDNF levels were not related to cognitive deficits in UHR and HC groups while the lower BDNF level in the former persisted up to 6 months. Further research is needed in a large sample.

Modulation of brain network parameters associated with subclinical psychotic symptoms.

OBJECTIVE: Static deficits in small-world properties of brain networks have been described in clinical psychosis, but task-related modulation of network properties has been scarcely studied. Our aim was to assess the modulation of those properties and its association with subclinical psychosis and cognition in the general population. METHOD: Closeness centrality and small-worldness were compared between pre-stimulus baseline and response windows of an odd-ball task in 200 healthy individuals. The correlation between modulation of network parameters and clinical (scores in the Community Assessment of Psychological Experiences) and cognitive measures (performance in the dimensions included in the Brief Assessment of Cognition in Schizophrenia battery) was analyzed, as well as between these measures and the corresponding network parameters during baseline and response windows during task performance. RESULTS: In the theta band, closeness centrality decreased and small-worldness increased in the response window. Centrality and small-worldness modulation were, respectively, directly and inversely associated with subclinical symptoms. CONCLUSIONS: A widespread modulation of network properties in theta band was observed, with a transient increase of small-worldness during the response window, compatible with a transiently more integrated cortical activity associated to cognition. This supports the relevance of electroencephalography to study of normal and altered cognition and its substrates. A relative deficit in the ability to reorganize brain networks may contribute to subclinical psychotic symptoms.

Psychometric properties and validation of a four-item version of the Strauss-Carpenter scale in bipolar disorder.

BACKGROUND: Bipolar disorder is a chronic illness that impairs functioning and affects the quality of life of patients. The onset of this illness usually occurs at an early age, and the risk of relapse remains high for decades. Thus, due to the great clinical relevance of identifying long-term predictors of functioning in bipolar disorder, Strauss and Carpenter developed a scale composed of items known to have prognostic value. METHODS: To determine the clinical usefulness of the four-item Strauss-Carpenter scale in bipolar disorder, a 1-year prospective follow-up study was carried out. The internal consistency, convergent and discriminant validity, and test-retest reliability of the scale were assessed. We also compared the Strauss-Carpenter scale with the reference scales Global Assessment Functioning (GAF), Clinical Global Impression for Bipolar Disorder, the Modified Version (CGI-BIP-M) and the Sheehan Disability Scale (Sheehan). Additionally, a cut-off point for remission was established. RESULTS: The total sample was composed of 98 patients with a diagnosis of bipolar disorder. The four-item version of the Strauss-Carpenter scale showed to have appropriate psychometric properties, comparable to those of reference scales. The best cut-off point for remission was 14. CONCLUSIONS: The four-item version of the Strauss-Carpenter scale has suitable validity and reliability for the assessment of functioning in patients with bipolar disorder.