Train Your Brain: 60 Days to a Better Brain is an English-language version of a Japanese book written by Ryuta Kawashima. The original book sold over a million copies in Japan. Dr. Kawashima found that by performing simple mathematical calculations and reading books aloud, one could retain mental clarity and stave off the mental effects of aging. The book is based on this research. The concepts presented in Train Your Brain would later be used to create the Nintendo DS game Brain Age: Train Your Brain in Minutes a Day!.