Christopher A. Chaddock

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The "aberrant salience" model proposes that psychotic symptoms first emerge when chaotic brain dopamine transmission leads to the attribution of significance to stimuli that would normally be considered irrelevant. This is thought to occur during the prodromal phase of psychotic disorders, but this prediction has not been tested previously. In the present(More)
BACKGROUND White matter (WM) abnormalities are proposed as potential endophenotypic markers of bipolar disorder (BD). In a diffusion tensor imaging (DTI) voxel-based analysis (VBA) study of families multiply affected with BD, we previously reported that widespread abnormalities of fractional anisotropy (FA) are associated with both BD and genetic liability(More)
BACKGROUND Deficits in motivational salience processing have been related to psychotic symptoms and disturbances in dopaminergic neurotransmission. We aimed at exploring changes in salience processing and brain activity during different stages of psychosis and antipsychotic medication effect. METHODS We used fMRI during the Salience Attribution Task to(More)
BACKGROUND Using positron emission tomography (PET), we previously observed increases in 3,4-dihydroxy-6-[(18)F]fluoro-L-phenylalanine ((18)F-DOPA) uptake in the striatum of subjects at ultra-high risk (UHR) for psychosis, indicating elevated presynaptic dopamine synthesis capacity. The purpose of this study was to test if this finding would be replicated(More)
BACKGROUND Subtle abnormalities in frontal white matter have been reported in bipolar disorder. AIMS To assess whether impaired integrity of white matter tracts is associated with bipolar disorder and genetic liability for the disorder. METHOD A total of 19 patients with psychotic bipolar I disorder from multiply affected families, 21 unaffected(More)
BACKGROUND White matter abnormalities have been implicated in the aetiology of major depressive disorder; however, the relationship between the severity of symptoms and white matter integrity is currently unclear. AIMS To investigate white matter integrity in people with major depression and healthy controls, and to assess its relationship with depressive(More)
BACKGROUND Neuroimaging studies in humans have implicated both dysfunction of the medial temporal lobe (MTL) and the dopamine system in psychosis, but the relationship between them is unclear. We addressed this issue by measuring MTL activation and striatal dopaminergic function in individuals with an At Risk Mental State (ARMS) for psychosis, using(More)
Alterations in brain glutamate levels may be associated with psychosis risk, but the relationship to clinical outcome in at-risk individuals is unknown. Glutamate concentration was measured in the left thalamus and anterior cingulate cortex (ACC) using 3-Tesla proton magnetic resonance spectroscopy in 75 participants at ultra high risk (UHR) of psychosis(More)
22q11 deletion syndrome (22q11DS) is a common genetic condition associated with learning disability and high risk for psychiatric illness, in particular schizophrenia. Previous neuroimaging studies in children and adults with 22q11DS have uncovered a number of abnormalities, but have not differentiated between features relating to cognitive impairment and(More)
BACKGROUND Sexual dimorphism in human brain structure is well recognised, but less is known about gender differences in white matter microstructure. We used diffusion tensor imaging to explore gender differences in fractional anisotropy (FA), an index of microstructural integrity. We previously found increased FA in the corpus callosum in women, and(More)