Propentofylline and pentoxifylline were administered to patients age 65 years or older who were suffering from chronic cerebrocirculatory insufficiency. Changes in clinical symptoms and the level of cerebral blood flow before and after drug administration were compared. 123I-IMP single photon emission computed tomography was used to compare cerebral blood flow before treatment with that 3 months after initiation of therapy. Focal regions of interest were established in the cerebellum, the frontal, temporal, parietal, and occipital lobes, and the thalamus. Comparisons were made between patients age 75 years or older (very old age group) (n = 5) and those age 65 to 74 years (old age group) (n = 7). Complaints of dizziness and slight headache disappeared by the eighth week after the start of therapy in both age groups. Two of the five patients in the very old age group showed elimination of memory disturbance symptoms at the 12th week of treatment. Six of the seven patients in the old age group had no memory disturbance symptoms by the eighth week of treatment, which indicates a high therapeutic effect in this group. In the cerebral blood flow studies, no increases in blood flow after drug administration were observed in the very old age group. This finding is probably related to the poor level of recovery achieved in disturbances in memory in this group. In contrast, improvements in blood flow were observed for all regions of the brain monitored in the old age group, which is consistent with the amelioration of clinical symptoms observed in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)