Vitamin D supplementation and incident fractures
Vitamin D supplementation is a commonly recommended intervention for bone health, but data to support its impact on reducing fracture risk has been variable.
Dr. Mengru Wang
A study in the New England Journal of Medicine by LeBoff and colleagues has garnered much attention since its publication in July 2022.1 In the ancillary study of the Vitamin D and Omega-3-Trial (VITAL), the authors examined the impact of vitamin D supplementation versus placebo on incident fractures. The study found that vitamin D supplementation, as compared with placebo, led to no significant difference in the incidence of total, nonvertebral, and hip fractures in midlife and older adults over the 5-year period of follow-up.
The generalizability of these findings has been raised as a concern as the study does not describe adults at higher risk for fracture. The authors of the study specified in their conclusion that vitamin D supplementation does not reduce fracture risk in “generally healthy midlife and older adults who were not selected for vitamin D deficiency, low bone mass or osteoporosis.”
With a mean participant age of 67 and exclusion of participants with a history of cardiovascular disease, stroke, cirrhosis and other serious illnesses, the study does not reflect the multimorbid older adult population that geriatricians typically care for. Furthermore, efficacy of vitamin D supplementation on fracture risk may be the most impactful in those with osteoporosis and with severe vitamin D deficiency (defined by vitamin D 25[OH]D level less than 12 ng/mL).
In post hoc analyses, there was no significant difference in fracture risk in these subgroups, however the authors acknowledged that the findings may be limited by the small percentage of participants with severe vitamin D deficiency (2.4%) and osteoporosis included in the study (5%).
Lecanemab for mild cognitive impairment and early Alzheimer’s dementia
On Jan. 6, 2023, the Food and Drug Administration approved lecanemab, the second-ever disease-modifying treatment for Alzheimer’s dementia following the approval of aducanumab in 2021. Lecanemab is a monoclonal antibody targeting larger amyloid-beta oligomers, which has been shown in vitro to have higher affinity for amyloid-beta, compared with aducanumab. FDA approval followed shortly after the publication of the CLARITY-AD trial, which investigated the effect of lecanemab versus placebo on cognitive decline and burden of amyloid in adults with mild cognitive impairment and mild Alzheimer’s dementia. Over an 18-month period, the study found that participants who received lecanemab, compared with placebo, had a significantly smaller decline in cognition and function, and reduction in amyloid burden on PET CT.2
The clinical significance of these findings, however, is unclear. As noted by an editorial published in the Lancet in 2022, the difference in Clinical Dementia Rating-Sum of Boxes (CDR-SB) scale between the treatment and placebo groups was 0.45. On an 18-point scale, prior research has noted that a minimal clinically significance difference of 0.98 is necessary in those with mild cognitive impairment and 1.63 in mild Alzheimer dementia.3
Additionally, the CLARITY-AD trial reported that lecanemab resulted in infusion reactions in 26.4% of participants and brain edema (an amyloid-related imaging abnormality referred to as ARIA-E) in 12.6% of participants. This finding highlights concerns for safety and the need for close monitoring, as well as ongoing implications of economic feasibility and equitable access for all those who qualify for treatment.2
Social isolation and dementia risk
There is growing awareness of the impact of social isolation on health outcomes, particularly among older adults. Prior research has reported that one in four older adults are considered socially isolated and that social isolation increases risk of premature death, dementia, depression, and cardiovascular disease.4
A study by Huang and colleagues is the first nationally representative cohort study examining the association between social isolation and incident dementia for older adults in community dwelling settings. A cohort of 5,022 older adults participating in the National Health and Aging Trends Study was followed from 2011 to 2020. When adjusting for demographic and health factors, including race, level of education, and number of chronic health conditions, socially isolated adults had a greater risk of developing dementia, compared with adults who were not socially isolated (hazard ratio, 1.27; 95% confidence interval, 1.08-1.49). Potential mechanisms to explain this association include the increased risk of cardiovascular disease and depression in older adults who are socially isolated, thereby increasing dementia risk.
Decreased cognitive activity/engagement and access to resources such as caregiving and health care may also be linked to the increased risk of dementia in socially isolated older adults.5
Another observational cohort study from the National Health and Aging Trends Study investigated whether access and use of technology can lower the risk of social isolation. The study found that older adults who used email or text messaging had a lower risk of social isolation than older adults who did not use technology (incidence rate ratio, 0.64; 95% CI, 0.51-0.80).6 These findings highlight the importance of addressing social isolation as an important modifiable health risk factor, and the need for providing equitable access to technology in vulnerable populations as health intervention.
Dr. Mengru “Ruru” Wang is a geriatrician and internist at the University of Washington, Seattle. She practices full-spectrum medicine, seeing patients in primary care, nursing homes, and acute care. Dr. Wang has no disclosures related to this piece.
References
1. LeBoff MS et al. Supplemental vitamin D and incident fractures in midlife and older adults. N Engl J Med. 2022;387(4):299-30.
2. van Dyck CH et al. Lecanemab in early Alzheimer’s disease. N Engl J Med. 2023;388(1):9-21.
3. The Lancet. Lecanemab for Alzheimer’s disease: tempering hype and hope. Lancet. 2022; 400:1899.
4. National Academies of Sciences, Engineering, and Medicine. Social Isolation and Loneliness in Older Adults: Opportunities for the Health Care System. Washington, DC: 2020, The National Academies Press.
5. Huang, AR et al. Social isolation and 9-year dementia risk in community dwelling Medicare beneficiaries in the United States. J Am Geriatr Soc. 2023 Jan 11. doi: 10.1111/jgs18140.
6. Umoh ME etal. Impact of technology on social isolation: Longitudinal analysis from the National Health Aging Trends Study. J Am Geriatr Soc. 2022 Dec 15. doi 10.1111/jgs.18179.