1. The effects of chronically administered aged garlic extract (AGE) on the age-related changes in a novel strain of senescence accelerated mouse (SAM) characterized by age-related brain atrophy (SAMP10) were investigated. 2. A solid diet containing 2% (w/w) AGE was given to SAM from 2 months of age. 3. The grading score of senescence in SAMP10 at 10 months of age was significantly higher than that of SAMR1, a reference strain for SAMP10. 4. Administration of AGE prevented the increase in the grading score of SAMP10 and SAMR1. 5. In behavioural evaluation, AGE improved learning and memory deficits of SAMP10 in both the passive and conditioned avoidance tests as well as the spatial memory test. 6. Treatment with AGE in SAMP10 prevented the decrease in brain weight and the atrophic changes in frontal brain at 12 months of age. 7. These results raise the possibility that AGE prevents physiological ageing and may be beneficial for age-related cognitive disorders in humans.