Volumetric measurements of the cerebrospinal fluid spaces in demented subjects and controls.

Forty-seven subjects 65 to 80 years of age, of whom 20 were demented and 27 were normal, were studied by computed tomography. Volumetric indices of ventricular (V%) and sulcal size (S%) were determined by pixel counts without knowledge of clinical status. V% was 5.30 (+/- 1.92) for the controls and 10.46 (+/- 4.78) for the demented subjects. S% was 6.14 (+/- 2.51) for the controls and 10.61 (+/- 3.32) for the demented subjects. In each case, differences between the two groups were significant (P less than 0.0001). When a subsample of 29 scans were analyzed using linear and volumetric measurements, the linear measurements showed less pronounced differences between the demented subjects and the controls. These findings explain the conflicting results of different investigators concerning variations in ventricular and sulcal size in dementia and normal aging.