Example 6: Evidence of neurodegeneration in schizophrenia, detected through mental testing and digital imaging of the retina. In a series of publications we have tracked members of the Dunedin birth cohort who were diagnosed with schizophrenia. We reported that different cognitive functions show change on different trajectories from childhood to adolescence and forward, past disease onset into midlife. The key deficit is in “processing speed”. It lags already in early childhood for individuals who will later develop schizophrenia, plus the deterioration of processing speed accelerates even more after schizophrenia diagnosis [59–61]. We further showed the benefits of applying digital retinal imaging technology in the study of schizophrenia, as the retina is a non-invasive window on the condition of the vasculature inside the brain and body. Through retinal imaging, we discovered expanded venular calibre is characteristic of schizophrenia, but not other related physical or mental disorders [62, 63]. This finding made for a captivating cover photo of a human retina that appeared on the cover of the December 2013 edition of the American Journal of Psychiatry. It has since been replicated
