Changes in the brain’s structure associated with schizophrenia have been increasingly well-documented with improvements in brain imaging techniques. While the abnormal deterioration of both gray matter and white matter have been observed in the brains of those with schizophrenia, a study published December 6th in the American Journal of Psychiatry provides new insight into how the trajectories of these two processes compare.

The study was led by Vanessa L. Cropley, Ph.D., a 2013 Young Investigator, and Andrew Zalesky, Ph.D., of the University of Melbourne, Australia, along with 2011 Distinguished Investigator Christos Pantelis, M.D., Ph.D., of the University of Melbourne. By looking at brain scans from 326 individuals with schizophrenia and 197 healthy comparison subjects, the team was able to compare the age-related rates of gray and white matter decline in both groups.

In all people, breakdowns of gray and white matter, which form the structural and connective components of the brain, respectively, are an inevitable manifestation of aging, beginning in middle age. In schizophrenia this aging of the brain occurs earlier and at more damaging rates.

Consistent with prior studies, researchers found that gray matter deterioration in people with schizophrenia is most severe during the early stages of the illness. The steepest rate of loss in the brain’s cortex occurs between the ages of 20 and 30; then, the researchers observed these peak rates begin to fall at about 6.5 years post-diagnosis. Overall, accelerated deterioration eventually slowed to rates observed in subjects without the illness by around 50 years of age. For reasons not yet clear, rates of reduced gray matter volume were significantly faster in males than in females, the researchers said.

In contrast, white matter volume in the cortex of study subjects with schizophrenia began to diverge from unaffected participants in the study beginning at around age 35, decreasing at a rate that was 60 percent faster than that of people without the illness. This accelerated pace continued throughout the remainder of the person living with schizophrenia’s life.

The delay of about 10 years between gray matter changes and white matter changes in schizophrenia, the authors note, parallels the 10-year delay between the relative ages of peak maturation in gray matter and white matter. The cause of this delay in deterioration remains to be determined, although the authors hypothesize that it may be caused by the functional relationship between gray matter and white matter across brain regions.

The large sample size of this study presents researchers with a newly refined picture of brain decay in schizophrenia. Although the molecular mechanisms behind these changes have not been identified, a better understanding of brain changes in schizophrenia should inform the development of more advanced therapeutic approaches.