Physical anomalies in first-degree relatives

How are physical abnormalities relevant to families of people with schizophrenia? 

Relatives of people with schizophrenia may show attenuated signs of the illness, such as physical features that are commonly identified with the disorder. Identifying these signs can help determine how genetics may contribute to the risk of schizophrenia.

What is the evidence for physical abnormalities in family members?

High quality evidence shows decreased rates of any cancer in relatives compared to the general population, similarly to findings in people with schizophrenia.

High quality evidence shows relatives have impairment in closed loop gain during smooth pursuit eye movement tasks. Moderate to high quality evidence also finds increased intrusive anticipatory saccades, impairment in fixational stability, and increased error rate in visual and memory guided saccades. EEG studies show the P50 ratio is significantly increased in relatives; P300 amplitude is reduced and latency is increased.

Moderate to high quality evidence shows a large increase in rates of neurological soft signs (mild motor or sensory anomalies), and a small increase in rates of movement disorders (dyskinesia or parkinsonism) in first-degree relatives.

Moderate quality evidence finds abnormal brain activation in relatives during cognitive tasks as well as reductions in volume in total grey matter, the hippocampus, third ventricle, bilateral anterior cingulate gyrus, right insula, left amygdala, left subcallosal gyrus, and the left inferior frontal gyrus.

Moderate to low quality evidence finds reduced glutamatergic metabolite levels in the dorsolateral prefrontal cortex, and reduced N-acetyl aspartate/creatine ratio in the anterior cingulate cortex and hippocampus in relatives.

March 2019

Last updated at: 5:28 am, 26th March 2019
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