Obsessive-compulsive symptoms in first episode psychosis and in subjects at ultra high risk for developing psychosis; onset and relationship to psychotic symptoms

Objective: To determine the prevalence of obsessive-compulsive symptoms and obsessive compulsive disorder in patients with schizophrenia or related disorders or subjects at ultra high risk for development of psychosis. Secondly, to determine the time of occurrence of obsessive-compulsive symptoms related to the onset of first psychosis. Method: We collected data on all patients who were referred consecutively to our specialized clinic for first episode psychosis patients and ultra high risk subjects in Amsterdam between 1 July 2006 and 1 July 2008. Diagnosis of psychotic disorders was established using the Comprehensive Assessment of Symptoms and History schedule. Obsessions and compulsions were defined in accordance with DSM-III-R criteria and assessed by clinicians. We analyzed the onset of obsessive-compulsive symptoms and its relation to the onset of first episode psychosis. Results: When a strict definition of obsessive-compulsive symptoms is used, 9.3% (n = 18) of patients with schizophrenia or a related disorder exhibited obsessive-compulsive symptoms and 1.5% also met criteria for obsessive-compulsive disorder. The onset of obsessive -compulsive symptoms occurred before, concurrent with and after onset of first episode psychosis in the following proportion of patients: 7/18, 3/18, 8/18. We found a prevalence of 20.7% of obsessive-compulsive symptoms in ultra high risk subjects. Conclusion: Using a strict definition of obsessive-compulsive symptoms, we found relatively low prevalence rates of obsessive-compulsive symptoms and obsessive-compulsive disorder in patients with schizophrenia or related disorders; the rates are even lower than known rates of obsessive-compulsive symptoms and obsessive-compulsive disorder in the general population. Obsessive-compulsive symptoms rates in ultra high risk subjects are comparable to those in the general population. Further investigation of the predictive validity of obsessive-compulsive symptoms in ultra high risk subjects for developing psychosis is needed. Obsessive-compulsive symptoms either develop prior, during or after the onset of first episode psychosi

Climatic influences on seasonal and spatial differences in soil CO" efflux

peer reviewe

Biophysical controls on CO2 fluxes of three Northern forests based on long-term eddy covariance data

Abstract in Undetermined Six to nine years of net ecosystem carbon exchange (NEE) data from forests in Hyytiala in Finland, Soro in Denmark and Norunda in Sweden were used to evaluate the interannual variation in the carbon balance. For half-monthly periods, average NEE was calculated for the night-time data. For the daytime data parameters were extracted for the relationship to photosynthetic active radiation (PAR). The standard deviation of the parameters was highest for Norunda where it typically was around 25% of the mean, while it was ca. 15% for Hyytiala and Soro. Temperature was the main controller of respiration and photosynthetic capacity in autumn, winter and spring but explained very little of the interannual variation in summer. A strong correlation between respiration and photosynthesis was also revealed. The start, end and length of the growing season were estimated by four different criteria. The start date could explain some of the variation in yearly total NEE and gross primary productivity (GPP) in Hyytiala and Soro, but the average maximum photosynthetic capacity in summer explained more of the variation in annual GPP for all sites than start, end or length of the growing season

Nitrogen saturation and net ecosystem production - Reply

Nitrogen (N) deposition alters ecosystem function in several ways, with important effects on N leaching and water quality, as well as on interspecific competition and biodiversity. These changes have been attributed to ecosystem N saturation, defined as the alleviation of N limitations on rates of biological function1. After an initial fertilization effect, N saturation has also been suggested to reduce plant function and growth2, eventually leading to forest dieback. Although our observation of a substantial positive effect of N deposition on forest carbon (C) sequestration3 does not imply the absence of nitrate losses or other negative effects, as rightly stressed by De Schrijver et al.4, the sustained response observed demonstrates that the fear of a generalized forest decline in response to N fertilization could be overstated, at least within the rather broad N deposition range explored in our analysis. The nature of the observed response of forest C sequestration toNdeposition, however, has been questioned outright by de Vries et al.5, who suggested that it could be an artefact resulting from the covariation between N deposition and other environmental variables. The arguments proposed against an overwhelming N effect, however, do not seemto stand up to close scrutiny. Far from implausible, a 200:1 sensitivity is nevertheless higher than suggested by long-term forest fertilization experiments. Potential problems withNmanipulation studies have already been discussed. In particular, they overlook the role of canopy N uptake, which enables plants to absorb a relevant fraction of incoming N without any competition from soil microbes. Canopy N uptake amounts to up to 70% of N deposition, providing as much as one-third of tree N requirements. The critical comparison of results from ecosystem manipulation and observational studies could be providing a rare, unforeseen insight into the key factors controlling C–N relations in forest ecosystems