Article

Mapping prodromal psychosis: a critical review of neuroimaging studies.

Institute of Psychiatry, Department of Psychosis Studies, London, UK.
European Psychiatry (Impact Factor: 3.21). 09/2011; 27(3):181-91.
Source: PubMed

ABSTRACT The onset of schizophrenia is usually preceded by a prodromal phase characterized by functional decline and subtle prodromal symptoms, which include attenuated psychotic phenomena, cognitive deterioration and a decline in socio-occupational function. Preventive interventions during this phase are of great interest because of the impressive clinical benefits. However, available psychopathological criteria employed to define a high risk state for psychosis have low validity and specificity. Consequently there is an urgent need of reliable neurocognitive markers linked to the pathophysiological mechanisms that underlie schizophrenia. Neuroimaging techniques have rapidly developed into a powerful tool in psychiatry as they provide an unprecedented opportunity for the investigation of brain structure and function. This review shows that neuroimaging studies of the prodromal phases of psychosis have the potentials to identify core structural and functional markers of an impending risk to psychosis and to clarify the dynamic changes underlying transition to psychosis and to address significant correlations between brain structure or function and prodromal psychopathology. Additionally, neurochemical methods can address the key role played by neurotransmitters such as dopamine and glutamate during the psychosis onset. To conclude, multimodal neuroimaging may ultimately clarify the neurobiology of the prodromal phases by the integration of functional, structural and neurochemical findings.

1 Bookmark
 · 
124 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Psychosis is a common non-motor symptom of Parkinson's disease whose pathogenesis remains poorly understood. Parkinson's disease in conjunction with psychosis has been shown to induce injury to extracorticospinal tracts as well as within some cortical areas. In this study, Parkinson's disease patients with psychosis who did not receive antipsychotic treatment and those without psychosis underwent diffusion tensor imaging. Results revealed that in Parkinson's disease patients with psychosis, damage to the left frontal lobe, bilateral occipital lobe, left cingulated gyrus, and left hippocampal white-matter fibers were greater than damage to the substantia nigra or the globus pallidus. Damage to white-matter fibers in the right frontal lobe and right cingulate gyrus were also more severe than in the globus pallidus, but not the substantia nigra. Damage to frontal lobe and cingulate gyrus white-matter fibers was more apparent than that to occipital or hippocampal fiber damage. Compared with Parkinson's disease patients without psychosis, those with psychosis had significantly lower fractional anisotropy ratios of left frontal lobe, bilateral occipital lobe, left cingu-lated gyrus, and left hippocampus to ipsilateral substantia nigra or globus pallidus, indicating more severe damage to white-matter fibers. These results suggest that psychosis associated with Par-kinson's disease is probably associated with an imbalance in the ratio of white-matter fibers be-tween brain regions associated with psychiatric symptoms (frontal lobe, occipital lobe, cingulate gyrus, and hippocampus) and those associated with the motor symptoms of Parkinson's disease (the substantia nigra and globus pallidus). The relatively greater damage to white-matter fibers in psychiatric symptom-related brain regions than in extracorticospinal tracts might explain why chosis often occurs in Parkinson's disease patients.
    Neural Regeneration Research 09/2013; 8(27):2548-56. · 0.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Early identification of individuals at clinical risk for psychotic illness is critical for early intervention. Current studies apply special assessment measures combined with neurocognitive, neuroimaging, and electrophysiology methodologies that have been discovered largely in schizophrenia research. While still limited in sample size, harmonized measures, and longitudinal data, these studies indicate the presence of abnormalities in the clinical-risk state. Such findings suggest that the onset of the psychotic process precedes late adolescence and clinical detection. Efforts at early identification, therefore, could benefit from large-scale studies. Computerized clinical assessment and neurocognitive testing are available and can move from academic sites to the community. Neuroimaging methods are increasingly available and can add to the prediction of transition. As a field, we need to move vigorously and responsibly toward early interventions that may prevent and ameliorate the developmental trajectory that leads to the emergence of a full psychotic disorder with devastating impact on individuals, families and communities.
    Current Behavioral Neuroscience Reports. 06/2014; 1(2).
  • [Show abstract] [Hide abstract]
    ABSTRACT: Schizophrenia has long been hypothesized to result from a disconnection syndrome due to a disruption of the association fibers of the brain. However, only with the advent of in vivo neuroimaging, a formal disconnectivity hypothesis for schizophrenia has been developed. Diffusion tensor MRI, a non-invasive technique which is sensitive to features of tissue microstructure and to the anatomy of the white matter fibers, has gained a crucial role in the field. Here, we provide a state-of-the-art review of structural connectivity abnormalities detected in schizophrenia and discuss the most relevant findings at preclinical, first episode drug-naïve, and chronic stages. Imaging studies showed white matter alterations from the preclinical to the chronic stage of the disease, which involve the corticospinal tracts, interhemispheric connections, long association white matter tracts, cerebello-thalamo-cortical circuit, and limbic system. Such abnormalities were found to be associated with the psychiatric and cognitive manifestations of the disease and to predict, at least partially, the patient clinical evolution and response to treatment.
    Schizophrenia Research 05/2014; · 4.43 Impact Factor

Full-text

Download
111 Downloads
Available from
May 21, 2014