Activation of the prefrontal cortex improves general prefrontal functions. We found from our fMRI experiments that bilateral prefrontal cortices as well as many parts of cerebral hemispheres were significantly activated during reading sentences, writing Kanji characters, counting numbers, or solving arithmetic problems. We, then, measured the effect of reading aloud and arithmetic calculation, by elderly people who were clinically diagnosed of dementia Alzheimer type, on their brain functions and daily life activities. Sixteen experimental and 16 age and MMSE-matched control subjects participated. The subjects of the experimental group were asked to perform a training program using learning tasks in reading and arithmetic for 2–6 days a week. The function of the frontal cortex of the subjects was assessed by FAB (frontal assessment battery at bedside). After six months of training, the FAB score of the experimental group showed a statistically significant improvement. The FAB score of the control group decreased slightly over the 6 month period, and the difference between the experimental and control groups was statistically significant. We also observed the restoration of communication and independence in the experimental group. The results indicate that learning tasks of reading aloud and arithmetic calculation can be used for cognitive rehabilitation of dementia patients.