A number of parameters assessed by computed tomography have been shown to differentiate between populations of psychiatric patients and normal controls. Changes in these parameters have been felt to result from atrophic processes. We hypothesized that changes in one parameter ought to result in related changes in another if they result from the same process. We tested this hypothesis by comparing CT scan results of density measurement with area and linear measurements of ventricular size and radiological assessments of cortical and cerebellar atrophy. Our results indicate that few statistically significant relationships appear to be present, the only such relationship being found between increased third ventricular size and cerebellar atrophy. We conclude that regional changes in brain density are not necessarily correlated with local changes in CSF volume, which suggests the involvement of disparate processes in their causation.