The contribution of rare variants to risk of schizophrenia in individuals with and without intellectual disability.

By performing a meta-analysis of rare coding variants in whole-exome sequences from 4,133 schizophrenia cases and 9,274 controls, de novo mutations in 1,077 family trios, and copy number variants from 6,882 cases and 11,255 controls, we show that individuals with schizophrenia carry a significant burden of rare, damaging variants in 3,488 genes previously identified as having a near-complete depletion of loss-of-function variants. In patients with schizophrenia who also have intellectual disability, this burden is concentrated in risk genes associated with neurodevelopmental disorders. After excluding known risk genes for neurodevelopmental disorders, a significant rare variant burden persists in other genes intolerant of loss-of-function variants; although this effect is notably stronger in patients with both schizophrenia and intellectual disability, it is also seen in patients with schizophrenia who do not have intellectual disability. Together, our results show that rare, damaging variants contribute to the risk of schizophrenia both with and without intellectual disability and support an overlap of genetic risk between schizophrenia and other neurodevelopmental disorders.

Mortality and Cumulative Exposure to Antipsychotics, Antidepressants, and Benzodiazepines in Patients With Schizophrenia: An Observational Follow-Up Study.

OBJECTIVE: Although mortality related to psychotropic medications has received much attention in recent years, little is known about the relationship between risk of death and cumulative antipsychotic load, and even less about the relationship between mortality and cumulative exposure to antidepressants or benzodiazepines. The authors examined these relationships using nationwide databases. METHOD: The authors used prospectively collected nationwide databases to identify all individuals 16-65 years of age with a schizophrenia diagnosis (N=21,492) in Sweden. All-cause and cause-specific mortality rates were calculated as a function of cumulative low, moderate, and high exposure to antipsychotics, antidepressants, and benzodiazepines from 2006 through 2010. RESULTS: Compared with no exposure, both moderate (adjusted hazard ratio=0.59, 95% CI=0.49-0.70) and high (adjusted hazard ratio=0.75, 95% CI=0.63-0.89) antipsychotic exposures were associated with substantially lower overall mortality. Moderate antidepressant exposure was associated with a lower mortality (adjusted hazard ratio=0.85, 95% CI=0.73-0.98), and high exposure, even lower (adjusted hazard ratio=0.71, 95% CI=0.59-0.86). Exposure to benzodiazepines showed a dose-response relationship with mortality (hazard ratios up to 1.74 [95% CI=1.50-2.03]). CONCLUSIONS: Moderate and high-dose antipsychotic and antidepressant use were associated with 15%-40% lower overall mortality, whereas chronic high-dose use of benzodiazepines was associated with up to a 70% higher risk of death compared with no exposure. Since patients with anxiety and depressive symptoms may have a higher intrinsic risk of death, the finding for benzodiazepines may be attributable to some extent to residual confounding.

Early insulin resistance predicts weight gain and waist circumference increase in first-episode psychosis--A one year follow-up study.

First-episode psychosis (FEP) is associated with weight gain during the first year of treatment, and risk of abdominal obesity is particularly increased. To identify early risk markers of weight gain and abdominal obesity, we investigated baseline metabolic differences in 60 FEP patients and 27 controls, and longitudinal changes during the first year of treatment in patients. Compared to controls at baseline, patients had higher low-density lipoprotein, triglyceride and apolipoprotein B levels, and lower levels of high-density lipoprotein and apolipoprotein A-I but no difference in body mass index or waist circumference. At 12-month follow-up, 60.6% of patients were overweight or obese and 58.8% had abdominal obesity. No significant increase during follow-up was seen in markers of glucose and lipid metabolism or blood pressure, but increase in C-reactive protein between baseline and 12-month follow-up was statistically significant. Weight increase was predicted by baseline insulin resistance and olanzapine use, while increase in waist circumference was predicted by baseline insulin resistance only. In conclusion, insulin resistance may be an early marker of increased vulnerability to weight gain and abdominal obesity in young adults with FEP. Olanzapine should be avoided as a first-line treatment in FEP due to the substantial weight increase it causes. In addition, the increase in the prevalence of overweight and abdominal obesity was accompanied by the emergence of low-grade systemic inflammation.

Altered activation of innate immunity associates with white matter volume and diffusion in first-episode psychosis.

First-episode psychosis (FEP) is associated with inflammatory and brain structural changes, but few studies have investigated whether systemic inflammation associates with brain structural changes in FEP. Thirty-seven FEP patients (median 27 days on antipsychotic medication), and 19 matched controls were recruited. Serum levels of 38 chemokines and cytokines, and cardiovascular risk markers were measured at baseline and 2 months later. We collected T1- and diffusion-weighted MRIs with a 3 T scanner from the patients at baseline. We analyzed the association of psychosis-related inflammatory markers with gray and white matter (WM) volume using voxel-based morphometry and WM diffusion using tract-based spatial statistics with whole-brain and region-of-interest (ROI) analyses. FEP patients had higher CCL22 and lower TGFα, CXCL1, CCL7, IFN-α2 and ApoA-I than controls. CCL22 decreased significantly between baseline and 2 months in patients but was still higher than in controls. The association between inflammatory markers and FEP remained significant after adjusting for age, sex, smoking and BMI. We did not observe a correlation of inflammatory markers with any symptoms or duration of antipsychotic treatment. Baseline CCL22 levels correlated negatively with WM volume and positively with mean diffusivity and radial diffusivity bilaterally in the frontal lobes in ROI analyses. Decreased serum level of ApoA-I was associated with smaller volume of the medial temporal WM. In whole-brain analyses, CCL22 correlated positively with mean diffusivity and radial diffusivity, and CXCL1 associated negatively with fractional anisotropy and positively with mean diffusivity and radial diffusivity in several brain regions. This is the first report to demonstrate an association between circulating chemokine levels and WM in FEP patients. Interestingly, CCL22 has been previously implicated in autoimmune diseases associated with WM pathology. The results suggest that an altered activation of innate immunity may contribute to WM damage in psychotic disorders.

Antipsychotic treatment and mortality in schizophrenia.

BACKGROUND: It is generally believed that long-term use of antipsychotics increases mortality and, especially, the risk of cardiovascular death. However, there are no solid data to substantiate this view. METHODS: We identified all individuals in Sweden with schizophrenia diagnoses before year 2006 (N = 21 492), aged 17-65 years, and persons with first-episode schizophrenia during the follow-up 2006-2010 (N = 1230). Patient information was prospectively collected through nationwide registers. Total and cause-specific mortalities were calculated as a function of cumulative antipsychotic exposure from January 2006 to December 2010. RESULTS: Compared with age- and gender-matched controls from the general population (N = 214920), the highest overall mortality was observed among patients with no antipsychotic exposure (hazard ratio [HR] = 6.3, 95% CI: 5.5-7.3), ie, 0.0 defined daily dose (DDD)/day, followed by high exposure (>1.5 DDD/day) group (HR = 5.7, 5.2-6.2), low exposure (<0.5 DDD/day) group (HR = 4.1, 3.6-4.6), and moderate exposure (0.5-1.5 DDD/day) group (HR = 4.0, 3.7-4.4). High exposure (HR = 8.5, 7.3-9.8) and no exposure (HR = 7.6, 5.8-9.9) were associated with higher cardiovascular mortality than either low exposure (HR = 4.7, 3.7-6.0) or moderate exposure (HR = 5.6, 4.8-6.6). The highest excess overall mortality was observed among first-episode patients with no antipsychotic use (HR = 9.9, 5.9-16.6). CONCLUSIONS: Among patients with schizophrenia, the cumulative antipsychotic exposure displays a U-shaped curve for overall mortality, revealing the highest risk of death among those patients with no antipsychotic use. These results indicate that both excess overall and cardiovascular mortality in schizophrenia is attributable to other factors than antipsychotic treatment when used in adequate dosages.

Deletion of TOP3ß, a component of FMRP-containing mRNPs, contributes to neurodevelopmental disorders.

Implicating particular genes in the generation of complex brain and behavior phenotypes requires multiple lines of evidence. The rarity of most high-impact genetic variants typically precludes the possibility of accruing statistical evidence that they are associated with a given trait. We found that the enrichment of a rare chromosome 22q11.22 deletion in a recently expanded Northern Finnish sub-isolate enabled the detection of association between TOP3B and both schizophrenia and cognitive impairment. Biochemical analysis of TOP3ß revealed that this topoisomerase was a component of cytosolic messenger ribonucleoproteins (mRNPs) and was catalytically active on RNA. The recruitment of TOP3ß to mRNPs was independent of RNA cis-elements and was coupled to the co-recruitment of FMRP, the disease gene product in fragile X mental retardation syndrome. Our results indicate a previously unknown role for TOP3ß in mRNA metabolism and suggest that it is involved in neurodevelopmental disorders.

Does originating from a genetic isolate affect the level of cognitive impairments in schizophrenia families?

Earlier studies have detected differences in the prevalence, symptomatology and genetic risk variants of schizophrenia between a north-eastern Finnish genetic isolate and the rest of Finland. This study compared a population-based isolate sample (145 persons with schizophrenia, 304 first-degree relatives and 32 controls) with a rest of Finland sample (73 persons with schizophrenia, 100 first-degree relatives and 80 controls) in cognitive functioning. Persons from the isolate outperformed persons in the rest of Finland sample in verbal learning, verbal ability and cognitive flexibility in the schizophrenia groups and in verbal learning, speeded processing and attentional control in the relatives groups. The differences between the subsamples remained significant after taking into account an intragenic Reelin STR allele, previously associated with cognitive impairments and almost absent from the isolate, in addition to disorder characteristics and familial loading. In control groups, we observed no differences between the isolate and the rest of Finland. In conclusion, cognitive impairments were milder in schizophrenia patients and their first-degree relatives within than outside the isolate. An absence of differences between the control samples suggests that the differences in schizophrenia families may relate to genetic background, possibly to partly distinct variants affecting the liability inside and outside the isolate.

Cognitive impairments in schizophrenia and schizoaffective disorder: relationship with clinical characteristics.

The present study aimed to compare population-based familial samples of patients with schizophrenia (n = 218) and schizoaffective disorder (n = 62) and a healthy control group (n = 123). Patients with schizoaffective disorder outperformed patients with schizophrenia in verbal ability, processing speed, visual working memory, and verbal memory. When compared with controls, patients with schizoaffective disorder also had a generalized cognitive impairment. Adjusting for clinical characteristics removed significant differences between the patient groups. Irrespective of the diagnosis, patients with the most severe negative symptoms and highest dose of antipsychotics had the most severe cognitive impairments, whereas mood symptoms were not related to cognitive performance. In conclusion, people with schizoaffective disorder have severe cognitive impairments, but the impairments are milder than in schizophrenia. Mood symptoms may not explain the difference between the diagnostic groups in cognitive functions, but the difference may be related to differences in the severity of negative symptoms.

Sex differences in cognition among persons with schizophrenia and healthy first-degree relatives.

Previous research suggests differences between women and men in the clinical features of schizophrenia, but studies examining sex differences in neuropsychological functioning have reached inconsistent results. In the present study, sex differences in cognition and clinical features were investigated in population-based samples of participants with schizophrenia (n=218), their healthy first-degree relatives (n=438) and controls (n=123). Sex differences in illness features were small; nevertheless, women with schizophrenia had less negative symptoms and lived independently more often than men. The schizophrenia group had impairments in all studied neuropsychological domains, and the relatives were impaired in processing speed and set-shifting. In all groups, women performed better than men in processing speed, set-shifting and verbal episodic memory, whereas men outperformed women in visual working memory. The group-by-sex interaction was significant in two variables: women outperformed men in the relatives group in immediate verbal reproduction and in the use of semantic clustering as a learning strategy, while there was no sex difference in the schizophrenia group. In conclusion, sex differences in cognition are mostly similar in schizophrenia to those among controls, despite sex differences in illness features. The preservation of sex differences also in first-degree relatives supports the conclusion.