Physical anomalies in relatives

How are physical anomalies relevant to relatives of people with bipolar disorder?

Relatives of people with bipolar disorder may show attenuated signs of the illness, such as physical features commonly identified with the disorder. These may include structural and/or functional anomalies as well as sleep disturbances.

What is the evidence for physical anomalies in relatives?

Moderate quality evidence suggests relatives of people with bipolar disorder show increased grey matter volume in the right inferior frontal gyrus, the left supramarginal gyrus, and the left superior temporal gyrus compared to controls. Decreased grey matter volume was found in relatives in the right lingual gyrus, the right cerebellum, and the right superior frontal gyrus. There were decreases in white matter integrity in relatives compared to controls in the right corpus callosum body, left corpus callosum splenium, and the left corticospinal tract.

Across all functioning tasks, relatives showed increased brain activation in the ventral anterior cingulate, right amygdala, and parahippocampal gyrus, and decreased activation in the right inferior parietal gyrus, left postcentral gyrus, and left superior parietal gyrus. During cognitive tasks, relatives showed increased activation in the frontal lobe, right caudate, right inferior frontal gyrus, dorsal anterior cingulate, and left middle temporal gyrus/superior temporal gyrus and decreased activation in the parietal lobe. During emotion processing, relatives showed increased activation in the right amygdala, right parahippocampal gyrus, and right middle occipital gyrus. During reward processing, relatives showed increased activation in the anterior and medio-orbital parts of the prefrontal cortex.

Relatives showed a large increase in the P50 ratio compared to controls. The P50 ratio is measured with EEG and increases are indicative of reduced cortical inhibition. There was also higher relative amplitude of the sleep-wake cycle in relatives compared to people with bipolar disorder.

March 2022

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Last updated at: 2:39 pm, 31st March 2022
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