Galway Studies

Bipolar Disorder

Bipolar Disorder is an illness characterised by extremes of mood, ranging from major depression to elation and psychosis. Thanks to advances in technology in brain imaging and molecular biology, research has shown that bipolar disorder is the result of a complex interplay of psychosocial and neurobiological factors including genetics, brain development, structure and function. The Galway Bipolar Study explores structural and diffusion magnetic resonance imaging (MRI) changes and the potential links with clinical and functional factors.


First Episode Psychosis

Psychosis is a broad term that refers to a cluster of mental illnesses resulting from when a person suffers distressing experiences due to a loss of contact with reality. It is not a disease on its own, but a symptom that can be present in a number of psychiatric conditions, such as schizophrenia, schizoaffective disorder, bipolar disorder (manic-depression), psychotic depression, and also as a result of misusing certain recreational drugs such as cannabis, LSD etc and alcohol (drug-induced psychosis). This study seeks to find out more about changes in brain structure and functioning that are associated with psychotic illness at this early stage of illness onset. A 3 year follow up study is currently underway to identify the extent of progressive brain structural abnormalities associated with the early stages of psychotic illness and their clinical, medication and course predictors.


Chronic Schizophrenia

Schizophrenia is a severe, disabling and complex psychiatric disorder. Common features include hallucinations, delusions, gross disorganization of speech or thought, cognitive and memory deficits and flattened affect. Despite anti-psychotic treatment approximately 30% of patients still remain symptomatic. The Galway schizophrenia study explores structural and diffusion MRI changes in chronic patients and the longitudinal effects of anti-psychotic medication.


 Methods 

Structural MRI

Structural MRI (sMRI) analysis allows for the investigation of the morphology of brain structure. At the Clinical Neuroimaging Laboratory analysis techniques include Voxel Based Morphometry, FreeSurfer for cortical thickness and curvature analysis and shape analysis using spherical harmonics. Structural brain changes are evident in many psychiatric disorders including bipolar disorder and schizophrenia. 

Above: Caudates showing shape change in bipolar patients. 

Below: FreeSurfer output showing alteration in cortical thickness of the superior temporal gyrus in first episode psychosis patients.

PET

Positron Emission Tomography (PET) imaging can be used to study brain function (such as glucose metabolism using fluorine-18 labeled fluorodeoxyglucose) or the distribution of certain molecules such as various receptors and transporters. For example, the recent discovery of a compound called Pittsburg Compound B (PIB) has meant that a PET scan is now available to measure the build-up of amyloid in the brain, in addition to being useful to determine Alzheimer’s type of dementia this now means researchers can examine whether treatments will alter the rate of amyloid build up. Molecular PET such as the scan below is also in use to study psychiatric diseases and has been useful in identifying molecules that are abnormal during depression, anxiety or psychosis.  

Diffusion MRI 

Diffusion MRI allows for a non-invasive examination of anatomical connectivity by sensitising the MR sequence to the diffusion of water. Diffusion MRI can identify changes in white matter microstructure. It is becoming a standard for examining white matter disorders like MS and psychiatric disorders with a white matter involvement, schizophrenia for example. 

A fractional anisotropy (FA) map. FA is a measure of the geometrically heterogenous diffusion of water in tissues. The colours represent the primary direction of diffusion. Red = left-right, green = anterior-posterior and blue = superior-inferior.

This is an example of the corticospinal tract and superior longitudinal fasciculus reconstructed with constrained spherical deconvolution (CSD) tractography.

Tractography uses mathematical algorithms to reconstruct tracts from the diffusion-MRI data. This creates an in vivo 3D model of the white matter tracts. Tractography is now used in planning some neurosurgery. It can also be used to isolate individual tracts for analysis or to visualise the course of white matter bundles.

Above are some examples of white matter bundles reconstructed with tractography for a study on schizophrenia. The genu of the corpus callosum, the corticospinal tract (CST), the anterior limb of the internal capsule (ALIC) and the superior longitudinal fasciculus (SLF). 

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