Publications by authors named "O J N Bloemen"
Glutamatergic dysfunction is implicated in schizophrenia pathoaetiology, but this may vary in extent between patients. It is unclear whether inter-individual variability in glutamate is greater in schizophrenia than the general population. We conducted meta-analyses to assess (1) variability of glutamate measures in patients relative to controls (log coefficient of variation ratio: CVR); (2) standardised mean differences (SMD) using Hedges g; (3) modal distribution of individual-level glutamate data (Hartigan's unimodality dip test).
View Article and Find Full Text PDFImportance: Proton magnetic resonance spectroscopy (1H-MRS) studies indicate that altered brain glutamatergic function may be associated with the pathophysiology of schizophrenia and the response to antipsychotic treatment. However, the association of altered glutamatergic function with clinical and demographic factors is unclear.
Objective: To assess the associations of age, symptom severity, level of functioning, and antipsychotic treatment with brain glutamatergic metabolites.
Article Synopsis
- - The study investigates the relationship between M receptor signaling deficits and associative learning and memory impairments in individuals with psychotic disorders, supported by previous findings linking these issues to fronto-temporal activation deficits.
- - Twenty-six patients with psychotic disorders and 29 matched healthy controls underwent fMRI while performing learning tasks, with one session under placebo and another under an M antagonist (biperiden).
- - Results indicated that patients showed DLPFC hypoactivation during memory tasks and greater hyperactivation in other brain regions after biperiden, suggesting that M receptor signaling may play a significant role in their cognitive deficits related to learning and memory.
Article Synopsis
- The study investigates the role of the muscarinic cholinergic system in cognitive dysfunction related to psychosis, specifically looking at choline concentrations in the anterior cingulate cortex (ACC) and striatum.
- It involved 30 subjects with psychosis and 30 healthy controls, using H-MRS and functional MRI to assess the effects of the M receptor antagonist biperiden on cognitive performance and brain connectivity.
- Results showed no significant differences in choline levels or cognitive performance between groups after placebo or biperiden, suggesting no major cholinergic abnormalities were present in the studied sample.
Background: 22q11.2 deletion syndrome (22q11DS), one of the most common recurrent copy number variant disorders, is associated with dopaminergic abnormalities and increased risk for psychotic disorders.
Aims: Given the elevated prevalence of substance use and dopaminergic abnormalities in non-deleted patients with psychosis, we investigated the prevalence of substance use in 22q11DS, compared with that in non-deleted patients with psychosis and matched healthy controls.