The technology of structural MRI is based on the magnetisation properties of cellular protons. The application of a strong magnetic field causes the protons within cells to shift direction, which will return to their original position over time (“precession”). The rate of precession differs across tissue types (such as grey matter and white matter in the brain), which can be interpreted by specialised programs to represent a 3D image. Many mental disorders have shown brain structural changes investigated with MRI, including schizophrenia and bipolar disorder.

What is the evidence for changes in brain structure in PTSD?

Moderate quality evidence found small to medium-sized reductions in total brain volume, intracranial volume, left insula, right insula, total insula, superior frontal gyrus, left middle temporal gyrus, inferior temporal gyrus, left anterior cingulate, total anterior cingulate, rostral anterior cingulate, lateral orbitofrontal cortex total amygdala, left hippocampus, right hippocampus, and total hippocampus in people with PTSD compared to controls.

Moderate to low quality evidence found medium-sized effects of reduced hippocampus volume and large effects of reduced amygdala volume in people with PTSD who were exposed to childhood abuse compared to controls.

Moderate quality evidence found small to medium-sized reductions in grey matter, cerebral volume, temporal lobe, hippocampus, and vermis in children with PTSD compared to controls. There were also non-significant, small reductions in the amygdala.

Moderate to low quality evidence found increased PTSD symptom severity was significantly associated with decreased volume of the left, but not the right, hippocampus.

Compared to people with major depressive disorder, people with PTSD had reduced total brain volume and increased thalamus volume. Both PTSD and depression patients had significantly smaller hippocampal volume compared with controls, with no difference between the patient groups in this brain region.

August 2021

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The post MRI appeared first on NeuRA Library.

fMRI measures blood flow to determine activation and deactivation of the specific brain regions associated with particular tasks.

What is the evidence for fMRI findings in people with bipolar disorder?

Compared to controls, moderate quality evidence finds decreased activation in adults with bipolar disorder in the inferior frontal gyrus during cognitive and emotion tasks, and during a mania phase. There were also decreases in the lingual gyrus during cognitive tasks and euthymia, and in the putamen during cognitive tasks. There were increases in activation in the medial temporal lobe, putamen, pallidum, and caudate during cognitive tasks.

In children and adolescents with bipolar disorder, there was decreased activation in the right ventrolateral prefrontal cortex, right dorsolateral prefrontal cortex, right superior frontal gyrus, right dorsal cingulate cortex, and right dorsal striatum compared to age-matched controls. There was increased activation in the right amygdala, right limbic lobe, right parahippocampal gyrus, right medial prefrontal cortex, right subgenual cingulate cortex, right somatosensory association cortex, left ventral striatum, left ventrolateral prefrontal cortex, left cerebellum, left lentiform nucleus, putamen, and lateral globus pallidus.

There was increased activation in children with a parent with bipolar disorder in the right dorsolateral prefrontal cortex, right insula, right inferior parietal lobule, and left cerebellum compared to age-matched controls. Compared to children and adolescents with a parent with bipolar disorder, there was decreased activation in children and adolescents with bipolar disorder in the right dorsolateral prefrontal cortex, right insula, and left cerebellum.

Moderate to low quality evidence suggests more hypoactivation in the putamen of people with bipolar disorder than in the putamen of people with major depressive disorder, post-traumatic stress disorder, or an anxiety disorder. There were similar levels of hypoactivation across diagnoses in the prefrontal/insula and the inferior parietal clusters and similar levels of hyperactivation in the left amygdala/parahippocampal gyrus, the left thalamus, and the perigenual/dorsal anterior cingulate cortex.

During facial affect processing tasks

Compared to controls, moderate quality evidence suggests decreased activation in people with bipolar disorder in the bilateral ventrolateral prefrontal cortex, and increased activation in bilateral parahippocampal gyrus (including the amygdala), left putamen and left pulvinar. With fear-face stimuli, people with bipolar disorder showed decreased activation in bilateral inferior frontal gyri and the left anterior cingulated gyrus, and increased activation in the left parahippocampal gyrus, left putamen, and left pulvinar thalamus. With happy-face stimuli, people with bipolar disorder showed decreased activation in the right anterior cingulated gyrus and increased activation in bilateral caudate and the left parahippocampal gyrus.

Compared to age-matched controls, moderate to low quality evidence suggests decreased activation in children or adolescents in the left middle occipital gyrus, and the right inferior frontal gyrus, with increased activity in the right amygdala, right parahippocampal gyrus, left inferior frontal gyrus, and left putamen.

Compared to adults with bipolar disorder, moderate to low quality evidence suggests increased activation in children or adolescents with bipolar disorder in the right amygdala.

Compared to people with major depression, moderate quality evidence suggests decreased activation in people with bipolar disorder in the dorsal anterior cingulate gyrus, and increased activation in the parahippocampal gyrus (including the amygdala), bilateral ventral anterior cingulate gyri, and left pulvinar.

Compared to people with schizophrenia moderate quality evidence suggests decreased activation in people with bipolar disorder in bilateral occipital cunei, and increased activation in the left thalamus pulvinar.

During cognitive control tasks (perceived task difficulty and effort)

Compared to controls, moderate quality evidence suggests decreased activation in people with bipolar disorder in the right inferior frontal gyrus, the right caudate nucleus, the right angular gyrus, the left inferior temporal gyrus, the left inferior frontal gyrus and the left posterior cingulate gyrus. There was also increased activation in the left precentral, left superior frontal, and the right superior temporal gyrus of patients.

During executive functioning tasks

Compared to controls, moderate quality evidence suggests reduced activation in the striatum, supplementary motor area, precentral gyrus, left cerebral hemisphere, and left cerebellum and more activation in the left gyrus rectus and right middle temporal gyrus. During euthymia there was reduced activation in the striatum, left supplementary motor area, and right inferior parietal gyrus, and more activation in the left gyrus rectus, and right middle and superior temporal lobe. People with bipolar I disorder showed hypoactivation in the putamen, insula, amygdala, supplementary motor area, and left caudate nucleus, and hyperactivation the right superior temporal lobe and left superior frontal gyrus.

During response inhibition tasks

Compared to controls, moderate quality evidence suggests decreased activation in the right inferior frontal gyrus, left lentiform nucleus, left precuneus, and left postcentral gyrus, with no evidence of increased activation. During euthymia, patients showed decreased activation in the striatum, left supplementary motor area, right anterior cingulate cortex, left lentiform nucleus/putamen, right inferior frontal gyrus, left inferior parietal lobule, right inferior parietal lobule, and the left precuneus. Euthymic patients showed increased activation in the left superior temporal gyrus, right middle frontal gyrus, and in rostral parts of the right inferior frontal gyrus. During mania, patients showed decreased activation in the right inferior frontal gyrus, left medial frontal gyrus, and the anterior cingulate cortex, and increased activation in the right insula and bilateral basal ganglia

During attention tasks

Compared to age-matched controls, moderate quality evidence suggests decreased activation in children and adolescents with bipolar disorder in the right anterior cingulate cortex, right limbic areas (including the amygdala), right dorsolateral prefrontal cortex, right lentiform nucleus and right globus pallidus. Increased activation was found in the right middle frontal gyrus, left insula, and bilateral ventrolateral prefrontal cortex of patients.

During working memory tasks

Compared to controls, moderate quality evidence suggests decreased activation in the left precentral gyrus and left cerebellum, and increased activation in the left gyrus rectus, and right middle and superior temporal lobe. People with bipolar disorder in the euthymic state showed hypoactivation in the left precuneus, right inferior occipital gyrus, and dorsolateral prefrontal cortex, and hyperactivation in the left ventromedial prefrontal cortex and right superior temporal gyrus.

December 2021

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The post Functional magnetic resonance imaging appeared first on NeuRA Library.

MRI is based on the magnetisation properties of cellular protons. The application of a strong magnetic field causes the protons within cells to shift direction, which will return to their original position over time (“precession”). The rate of precession differs across tissue types (such as grey matter and white matter in the brain), which can be interpreted by specialised programs to represent a 3D image.

What is the evidence for MRI findings in people with bipolar disorder?

Grey matter decreases compared to controls

High quality evidence shows small decreases in hippocampal subfields in people with bipolar disorder. Moderate quality evidence also suggests decreases in bilateral insula, superior temporal gyrus, superior and ventral medial prefrontal cortex, anterior cingulate cortex, left dorsalmedial prefrontal cortex, left ventrolateral prefrontal cortex, and right precentral gyrus. Moderate to low quality evidence suggests decreases in left medial frontal, right inferior frontal, precentral frontal, left inferior longitudinal fasciculus, left insula, superior corona radiate, and the left limbic posterior cingulum.

In people with first-episode bipolar disorder, moderate to high quality evidence suggests small decreases in whole brain grey matter. In youth with bipolar disorder, moderate quality evidence found decreases in the left orbitofrontal cortex, right claustrum, and right dorsolateral prefrontal cortex. In people with bipolar disorder and psychotic symptoms (not necessarily diagnosed with bipolar I disorder), moderate quality evidence suggests decreases in bilateral superior frontal gyri, bilateral insula, bilateral median cingulated/paracingulate gyri, left anterior cingulate/paracingulate gyri, and right precentral gyrus (particularly in females). In people diagnosed with bipolar I disorder, decreases were also found in the right superior temporal gyrus, and the rolandic operculum.

Grey matter increases compared to controls

Moderate quality evidence suggests increases in the cerebellum, bilateral middle frontal gyrus, right middle temporal gyrus, right inferior temporal gyrus, the right middle occipital gyrus, left putamen, and left posterior cingulate cortex of people with bipolar disorder. In people diagnosed with bipolar I disorder, increases were also found in the left precuneus. In relatives of people with bipolar disorder, moderate to high quality evidence suggests small increases in intracerebral volume, with no differences in the thalamus, striatum, amygdala, hippocampus, pituitary, or frontal lobes. Compared to people with bipolar disorder, relatives also show a small increase in grey matter volume.

White matter decreases compared to controls

Moderate to high quality evidence suggests decreases in the posterior corpus callosum extending to the posterior cingulate cortex, with smaller reduced clusters in the left optic radiation and right frontal superior longitudinal tracts. In people with first-episode bipolar disorder, moderate to high quality evidence suggests small decreases in total white matter.

White matter increases compared to controls

Moderate to high quality evidence suggests small increases in the cerebellum and the right lenticular nucleus.

Ventricular changes

Moderate to high quality finds an increased risk of having a cavum septum pellucidum, and increased volume in the lateral and third ventricles.

Compared to people with schizophrenia

Moderate quality evidence suggests fewer grey matter reductions in people with bipolar disorder in the right dorsomedial frontal cortex and the left dorsolateral prefrontal cortex. While grey matter reductions were more extensive in male-dominated schizophrenia samples, there was no effect of gender on the findings in bipolar disorder. Moderate to high quality evidence shows fewer reductions in people with bipolar disorder in the amygdala and in hippocampal regions of the left cornu ammonis (CA)1, left CA2/3, left CA4/dentate gyrus, right presubiculum and right subiculum, with no differences in the left presubiculum or subiculum, or right CA1, CA2/3, or CA4/dentate gyrus.

Compared to people with major depression

Moderate to low quality evidence suggests increased grey matter volume in people with bipolar disorder in the right middle frontal gyrus, left hippocampus, right inferior temporal gyrus, left inferior parietal lobule, and right cerebellar vermis.

Compared to people with borderline personality disorder

Moderate to low quality evidence finds reduced grey matter volume and density in people with bipolar disorder in bilateral medial orbital frontal cortex, right insula, and right thalamus, and increases in the right putamen. In borderline personality disorder, grey matter was reduced in bilateral medial prefrontal cortex, bilateral amygdala, and right parahippocampal gyrus.

Medication effects

Compared to bipolar patients not on lithium treatment, high quality evidence shows those on lithium had small increased global grey matter volume. When comparing either group (lithium treated or lithium free) to controls, there were no differences in global grey matter volume. Lithium-treated patients showed fewer hippocampal reductions than patients treated with other medications.

December 2021

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