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 large effects of increased P50 ratio and reduced P50 suppression, a medium-sized effect of reduced P300 amplitude, a small to medium-sized effect of longer latency, and a small trend effect of reduced MMN amplitude in relatives of people with schizophrenia.

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 greater pituitary volume, and 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 high quality finds a medium-sized increase in glutamate+glutamine levels in the frontal lobes of relatives. Moderate to low quality evidence suggests reduced glutamate/glutamine ratio in the dorsolateral prefrontal cortex of relatives, and reduced N-Acetylaspartate/creatine ratio in the anterior cingulate cortex and hippocampus of relatives.

October 2020

Last updated at: 4:32 am, 31st October 2020
To view documentation related to this topic download the files below
Fact Sheet Technical Commentary

NeuRA Libraries

Title Colour Legend:
Green - Topic summary is available.
Orange - Topic summary is being compiled.
Red - Topic summary has no current systematic review available.