Temporal lobe volume changes in people at high risk of schizophrenia with psychotic symptoms
Lawrie SM, Whalley HC, Abukmeil SS, Kestelman JN, Miller P, Best JJ, Owens DG and Johnstone EC;
Commented by , 25 Sep 2002
Aim of the study
Abnormalities of brain structure, particularly of the temporal lobes, have been demonstrated in schizophrenia with magnetic resonance imaging (MRI). These are thought to be neurodevelopmental in origin, but when they become evident is unknown.
Therefore, the aim of this study was to examine the change of temporal lobe volumes in people who were initially well, but at high risk of schizophrenia.
Method
The high risk of schizophrenia group consisted of 66 Scottish participants who had at least two first- or second-degree relatives with schizophrenia. Furthermore, a control group of 20 healthy individuals without any family history of schizophrenia which was similar in age was examined.
All subjects were videotaped and rated at each clinical assessment with the Present State Examination in order to examine psychotic symptoms.
Both groups had a structural MRI scan of the whole brain at baseline which was repeated after approximately two years. Regions of interest, specifically the amygdala-hippocampus complex and the temporal lobes, were traced semi-automatically by three masked raters with good inter-and intrarater reliability and volumes were calculated.
Differential changes over time in the high-risk and healthy control groups were statistically examined with repeated measures analysis of variance.
Results
The second scans were done at an average of 1.8 years after the first assessment. The mean ages of the high-risk and of the control group were approximately 23.1 and 22.9 years and the groups were similar in other parameters, as well.
Overall, there were no significant differences in regional brain volume changes in over two years between high-risk and healthy participants. This held true for the temporal lobes and for the amygdala-hippocampus regions.
However, within the high-risk group, the 19 people who had psychotic symptoms had a mean reduction of 2163 mm3 in the right temporal lobe compared with 97 mm3 in the 47 without symptoms (P=0.02).
12 of these 19 people with psychotic symptoms had already had positive symptoms at baseline, but did not meet the criteria for schizophrenia.
Discussion
The authors did not find evidence to support their main hypothesis, which was a reduction in temporal lobes in all high-risk individuals, because there was no significant difference compared to the control group.
However, their findings suggest that people at high risk of schizophrenia who already have psychotic symptoms show reductions in temporal lobe volumes.
The authors discuss this result in the sense that brain structure may change in association with psychotic symptoms. The clinical implications of this finding would be that reductions in temporal lobe volumes could predict the onset of schizophrenia.
This also suggests general possibilities for early detection in the future, although this would require much more sensitive methods.