Anticonvulsant drug use and low bone mass in adults with neurodevelopmental disorders

BACKGROUND: Use of anticonvulsant drugs among adults with neurodevelopmental disorders may be an important risk factor for both osteoporosis and skeletal fractures. AIM: To determine the relationship between anticonvulsant drug use and both low bone mass and bone fractures in such adults. DESIGN: Cross-sectional study of 273 adults with neurodevelopmental disorders, 40% of whom were receiving one or more anticonvulsant drugs. SETTING: Single Canadian long-term care facility. METHODS: Demographic data were abstracted from each resident's chart in a standardized manner, including body mass, degree of mobility, major falls within the previous 12 months, and all medications. Quantitative calcaneal ultrasonography was performed on each resident without knowledge of their current drug use. The Quantitative Ultrasound Index was employed to express 'bone stiffness'. Low bone mass was defined as a T-score 2.5 SDs below the norm for young healthy adults. RESULTS: Compared to non-users (15.5%), low bone mass was more prevalent among those taking either one (20.3%; OR 1.7, 95%CI 0.6-4.4) or two or more anticonvulsant agents (42.2%, OR 5.9, 95%CI 2.2-16.2). The risk of recent skeletal fractures was not significantly greater in those taking a single anticonvulsant than in non-users (28.6% vs. 21.6%; OR 1.0, 95%CI 0.4-2.8), but tended to be higher in those taking two or more (48.7%; OR 2.2, 95%CI 0.8-5.9). CONCLUSIONS: Adults with neurodevelopmental disorders residing in a long-term care facility have a high rate of both low bone mass and skeletal fractures, especially with concomitant use of anticonvulsant drugs. These individuals should be assessed for the presence of low bone mass, and may warrant prophylactic treatment against bone loss, including calcium and vitamin D supplementation.