Dementia and osteoporosis in a geriatric population: Is there a common link?

Abstract

AIMTo determine the existence of a common pathological link between dementia and osteoporosis through reviewing the current evidence base.METHODSThis paper reviews the current literature on osteoporosis and dementia in order to ascertain evidence of a common predisposing aetiology. A literature search of Ovid MED-LINE (1950 to June 2016) was conducted. The keywords “osteoporosis”, “osteoporotic fracture”, “dementia” and “Alzheimer’s disease” (AD) were used to determine the theoretical links with the most significant evidence base behind them. The key links were found to be vitamins D and K, calcium, thyroid disease, statins, alcohol and sex steroids. These subjects were then searched in combination with the previous terms and the resulting papers manually examined. Theoretical, in vitro and in vivo research were all used to inform this review which focuses on the most well developed theoretical common causes for dementia (predominantly Alzheimer’s type) and osteoporosis.RESULTSDementia and osteoporosis are multifaceted disease processes with similar epidemiology and a marked increase in prevalence in elderly populations. The existence of a common link between the two has been suggested despite a lack of clear pathological overlap in our current understanding. Research to date has tended to be fragmented and relatively weak in nature with multiple confounding factors reflecting the difficulties of in vivo experimentation in the population of interest. Despite exploration of various possible mechanisms in search for a link between the two pathologies, this paper found that it is possible that these associations are coincidental due to the nature of the evidence available. One finding in this review is that prior investigation into common aetiologies has found raised amyloid beta peptide levels in osteoporotic bone tissue, with a hypothesis that amyloid beta disorders are systemic disorders resulting in differing tissue manifestations. However, our findings were that the most compelling evidence of a common yet independent aetiology lies in the APOE4 allele, which is a well-established risk for AD but also carries an independent association with fracture risk. The mechanism behind this is thought to be the reduced plasma vitamin K levels in individuals exhibiting the APOE4 allele which may be amplified by the nutritional deficiencies associated with dementia, which are known to include vitamins K and D. The vitamin theory postulates that malnutrition and reduced exposure to sunlight in patients with AD leads to vitamin deficiencies.CONCLUSIONRobust evidence remains to be produced regarding potential links and regarding the exact aetiology of these diseases and remains relevant given the burden of dementia and osteoporosis in our ageing population. Future research into amyloid beta, APOE4 and vitamins K and D as the most promising aetiological links should be welcomed.

Clinical Characteristics of Primary and Secondary Osteoporotic Fractures: Data from Single Referral Center Emergency Department

“…Bohlken et al[30] studied the relationship between the incidence of dementia and hip fracture and reported that patients with dementia had lower BMD and higher risk of hip fractures than normal subjects. Downey et al[31] reported that β-amyloid, Apolipoprotein E4, and vitamins K and D were involved in the link between dementia and osteoporosis.…”

Community‐dwelling older men with dementia are at high risk of hip fracture, but not any other fracture: The Concord Health and Aging in Men Project

“…It has been hypothesized that there might be common etiologies between dementia and osteoporosis that both have a similar epidemiology with a marked increase in prevalence in older adults . However, we did not find any associations between dementia and change in BMD over time, which suggests there might not be an independent link.…”

Relationships between the Bone Expression of Alzheimer Disease-Related Genes, Bone Remodelling Genes and Cortical Bone Structure in Neck of Femur Fracture

“…The mean age of the 66 patients investigated was 81. 9 Table 2). Including those identified in-hospital, 13 (19.69 %) participants had a diagnosis of dementia.…”

“…Previous studies have sought to determine links between increased fracture risk and the development of AD and other forms of dementia [9][10][11][12][13][14][15]. A number of risk factors have been identified through observational cohort studies linking these pathologies, including age, gender, vitamin D status, bone mineral density (BMD) and comorbidities, such as chronic kidney disease [16].…”