We appreciate the comment by Kanna and Roffe regarding our article.1 Metacarpal computed x-ray densitometer measurement has been validated, and its accuracy was found to be comparable with the better known but less available method of dual-energy x-ray absorptiometry. In previous studies on patients with Parkinson disease or stroke, we found second metacarpal BMD by computed x-ray densitometer measurement to correlate with risk of hip fracture.2,3 Therefore, reduced second metacarpal BMD in patients with Alzheimer disease appears to reflect a decrease throughout the appendicular skeleton. When patients were divided into 2 groups according to their Mini-Mental State Examination (MMSE) score, the incidence of a hip fracture was higher in patients with a lower MMSE score, and risedronate therapy reduced the incidence almost equally in the 2 groups with higher or lower scores. Although we did not assess the level of physical exercise of the patients, their mental state may have affected their physical activities, and it has to be addressed in future studies. When both patient groups were analyzed together, the BMD correlated positively with dietary intake of calcium (P<.05), and 473 patients with sunlight exposure with none or less than 15 minutes per week had low BMD compared with the 27 patients with sunlight exposure more than 15 minutes per week (P<.01). This fact may be regarded, in part, as one of the effects of physical activity as well.
Sato Y, Kanoko T, Satoh K, Iwamoto J. Prevention of Hip Fracture in Elderly Women With Alzheimer Disease—Reply. Arch Intern Med. 2006;166(10):1144-1145. doi:10.1001/archinte.166.10.1145