Characterization of deficit schizophrenia and reliability of the bidimensional model of its negative symptomatology

Positive association between increased homocysteine and deficit syndrome in Chinese patients with chronic schizophrenia: a large-scale cross-sectional study

Emerging studies indicate that oxidative stress may contribute to deficit syndrome (DS) in patients with schizophrenia. Homocysteine (Hcy) is a well-known marker and mediator of oxidative stress that exhibits tight associations with schizophrenia. However, no previous studies have assessed the relationship of DS with Hcy. This study evaluated the prevalence, clinical characteristics, and association of DS with Hcy in 491 patients with schizophrenia. Plasma levels of Hcy and other metabolic parameters were measured. Positive and Negative Syndrome Scale and the proxy scale for deficit syndrome were employed to assess psychiatric symptoms and DS. The logistic regression model was conducted to assess independent factors associated with DS, and the Area Under the Curve (AUC) was used to assess the performance of our model. There was a high incidence of hyperhomocysteinemia (58.8%) and DS (24.4%). Plasma Hcy levels were significantly higher in patients with DS. Age, Hcy levels, and psychiatric symptoms were independently associated with DS. The combination of these variables perfectly differentiated DS and non-DS patients with an AUC value of 0.89. Our study suggests that elevated Hcy levels may be related to DS. Routine monitoring of Hcy is essential and may facilitate early detection of DS in patients with schizophrenia.

Cortical morphology in patients with the deficit and non-deficit syndrome of schizophrenia: a worldwide meta- and mega-analyses

Converging evidence suggests that schizophrenia (SZ) with primary, enduring negative symptoms (i.e., Deficit SZ (DSZ)) represents a distinct entity within the SZ spectrum while the neurobiological underpinnings remain undetermined. In the largest dataset of DSZ and Non-Deficit (NDSZ), we conducted a meta-analysis of data from 1560 individuals (168 DSZ, 373 NDSZ, 1019 Healthy Controls (HC)) and a mega-analysis of a subsampled data from 944 individuals (115 DSZ, 254 NDSZ, 575 HC) collected across 9 worldwide research centers of the ENIGMA SZ Working Group (8 in the mega-analysis), to clarify whether they differ in terms of cortical morphology. In the meta-analysis, sites computed effect sizes for differences in cortical thickness and surface area between SZ and control groups using a harmonized pipeline. In the mega-analysis, cortical values of individuals with schizophrenia and control participants were analyzed across sites using mixed-model ANCOVAs. The meta-analysis of cortical thickness showed a converging pattern of widespread thinner cortex in fronto-parietal regions of the left hemisphere in both DSZ and NDSZ, when compared to HC. However, DSZ have more pronounced thickness abnormalities than NDSZ, mostly involving the right fronto-parietal cortices. As for surface area, NDSZ showed differences in fronto-parietal-temporo-occipital cortices as compared to HC, and in temporo-occipital cortices as compared to DSZ. Although DSZ and NDSZ show widespread overlapping regions of thinner cortex as compared to HC, cortical thinning seems to better typify DSZ, being more extensive and bilateral, while surface area alterations are more evident in NDSZ. Our findings demonstrate for the first time that DSZ and NDSZ are characterized by different neuroimaging phenotypes, supporting a nosological distinction between DSZ and NDSZ and point toward the separate disease hypothesis.

The relationship between human development and prevalence of deficit schizophrenia: Results from a systematic review and meta-analysis

This study examined the relationship between the prevalence of deficit schizophrenia (DS) and a country's Human Development Index (HDI). A systematic review and meta-analysis of the literature published in the last decade were conducted to acquire data on the worldwide prevalence of deficit syndrome in schizophrenia cohorts and examine the correlation between DS prevalence and the HDI of the countries in the review. Twenty-six studies meeting our eligibility criteria provided prevalence data on DS in 14 countries with both low-to-middle and high-incomes, ranging from 14.34%-to 61.57%. The pooled prevalence of DS was 32.19% (95% CI = 26.17 to 38.52). Statistical analysis yielded a correlation coefficient (r) of -0.518 (95% CI = -0.754 to -0.164; p = 0.007), indicating a moderate inverse correlation between DS prevalence and HDI. This relationship remained significant in partial correlation analysis after controlling for potential sources of bias in the DS estimates (r = -0.489, p = 0.013). Our results show that schizophrenia cohorts from low-to-middle-income countries are more prone to primary and enduring negative symptoms, and contribute to the emerging evidence questioning the axiom that schizophrenia in the developing world has a better course than in high-income countries.

Serum BDNF levels, glycolipid metabolism in deficit schizophrenia: A case-control study

BACKGROUND

Few studies have compared serum BDNF and glycolipid profiles in patients with deficit schizophrenia (DS) and non-deficit schizophrenia (NDS). We aimed to compare BDNF and glycolipid profiles between DS and NDS patients and healthy controls, and to investigate the relationship between BDNF, glycolipid profiles in DS and NDS patients.

METHODS

A total of 591 patients with chronic schizophrenia (SZ) and 238 healthy controls participated in this study. According to Proxy for the Deficit Syndrome Scale, SZ patients were divided into DS (n = 158) and NDS (n = 273) patients. Psychiatric symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Serum BDNF levels were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

BDNF levels were significantly lower in SZ patients than those in healthy controls (7.81 ± 2.98 ng/ml vs. 11.96 ± 2.29 ng/ml, P < 0.01). Furthermore, BDNF levels were lower in DS group than those in NDS group (P = 0.007, OR = 0.846, 95% CI = 0.750-0.955). Lower triglyceride levels were also an independent predictor for DS patients (P = 0.007, OR = 0.846, 95% CI = 0.750-0.955). Serum BDNF levels were negatively associated with the severity of deficit syndrome in SZ patients (β = -1.151, t = -2.559, P = 0.011). In DS group, triglycerides were associated with PANSS negative subscore (β = -0.262, t = -2.994, P = 0.003) and depressive factor subscore (β = 0.282, t = 2.146, P = 0.035).

CONCLUSION

Serum BDNF and triglycerides may be informative biomarkers of DS in SZ patients. The differences in glycolipid metabolism patterns between DS and NDS patients indicate that deficit syndrome is an independent endophenotype of SZ patients.

The Deficit Schizophrenia Subtype Is Associated with Low Adherence to the Mediterranean Diet: Findings from a Case–Control Study

Accumulating evidence indicates that individuals with schizophrenia show poor dietary habits that might account for increased susceptibility to cardiovascular diseases in this population. However, it remains unknown whether this observation can be generalized over the whole population of individuals with schizophrenia. Therefore, in this study we aimed to investigate dietary habits, in terms of adherence to the Mediterranean diet (MD) in subjects with the deficit subtype of schizophrenia (SCZ-D), those with non-deficit subtype (SCZ-ND), and healthy controls (HCs). We recruited 45 individuals with SCZ-ND, 40 individuals with SCZ-D, and 60 HCs. Dietary habits were assessed using the Food Frequency Questionnaire-6 with a 12-month recall. Adherence to MD was decreased only in subjects with SCZ-D compared with HCs. Lower adherence to MD was associated with significantly higher levels of clinician-rated and self-reported negative symptoms (including alogia, avolition, and anhedonia). No significant correlations of adherence to MD with depressive symptoms were found. Lower adherence to MD was related to significantly higher body mass index in subjects with schizophrenia, but not in HCs. Our results indicate that poor adherence to MD is associated with a diagnosis of SCZ-D, higher severity of negative symptoms, and greater risk of developing overweight or obesity.

Pareidolia in Schizophrenia and Bipolar Disorder

While there are many studies on pareidolia in healthy individuals and patients with schizophrenia, to our knowledge, there are no prior studies on pareidolia in patients with bipolar disorder. Accordingly, in this study, we, for the first time, measured pareidolia in patients with bipolar disorder (N = 50), and compared that to patients with schizophrenia (N = 50) and healthy controls (N = 50). We have used (a) the scene test, which consists of 10 blurred images of natural scenes that was previously found to produce illusory face responses and (b) the noise test which had 32 black and white images consisting of visual noise and 8 images depicting human faces; participants indicated whether a face was present on these images and to point to the location where they saw the face. Illusory responses were defined as answers when observers falsely identified objects that were not on the images in the scene task (maximum illusory score: 10), and the number of noise images in which they reported the presence of a face (maximum illusory score: 32). Further, we also calculated the total pareidolia score for each task (the sum number of images with illusory responses in the scene and noise tests). The responses were scored by two independent raters with an excellent congruence (kappa > 0.9). Our results show that schizophrenia patients scored higher on pareidolia measures than both healthy controls and patients with bipolar disorder. Our findings are agreement with prior findings on more impaired cognitive processes in schizophrenia than in bipolar patients.