To the Editor We read with interest the findings by Jones et al.1 However, the authors may have overinterpreted the findings. First, correlations between the different dimensions of the Community Assessment of Psychic Experiences (CAPE) (positive, depressive, and negative) typically are in the order of 0.6 to 0.8. For example, in the data set of the Dutch Genetic Risk and Outcome of Psychosis Study, the correlation between the positive and the negative dimension was 0.6 and the correlation between the negative and the depressive dimension was 0.7. In other words, the CAPE negative dimension is a proxy for both the CAPE positive dimension and the CAPE depression dimension. Therefore, claiming a specific association with the negative dimension cannot be considered valid unless the correlations with the other dimensions are partialled out—if at all possible. Given this problem, an alternative explanation may be more likely.
van Os J. Measures of Psychosis Proneness and Genetic Risk for Schizophrenia. JAMA Psychiatry. 2016;73(6):638. doi:10.1001/jamapsychiatry.2016.0227