Dementia and hip fractures: development of a pathogenic framework for understanding and studying risk

Abstract

Dementia and hip fractures are 2 conditions that are seen primarily in older adults, and both are associated with substantial morbidity and mortality. An individual with dementia is up to 3 times more likely than a cognitively intact older adult to sustain a hip fracture. This may occur via several mechanisms, including (1) risk factors that are common to both outcomes; (2) the presence of dementia increasing hip fracture incidence via intermediate risk factors, such as falls, osteoporosis, and vitamin D; and (3) treatment of dementia causing side effects that increase hip fracture risk. We describe a model that applies these 3 mechanisms to explain the relationship between dementia and hip fractures. Comprehensive understanding of these pathways and their relative influence on the outcome of hip fracture will guide the development of effective interventions and potentially improve prevention efforts.

Keywords: Alzheimer disease; cognitive impairment; fragility fractures; multimorbidity; pathogenesis.

Figure 1.

Pathogenic framework for dementia and hip fractures. Several intermediate risk factors are interrelated, and this is described in the text. These connections are not depicted in the Figure for ease of reading. This framework depicts 3 mechanisms by which dementia increases hip fracture risk: (1) shared risk factors increase co-occurrence; (2) dementia increases the risk of multiple intermediate risk factors, which in turn, increase hip fracture risk; (3) treatment of dementia increases hip fracture risk.