Cognitive decline and bone loss: bidirectional associations in women

By Dr Emily Lathlean MB BS, FRACGP
A longitudinal study of 1741 women and 620 men aged 65 years and over has found associations between cognitive decline and bone loss in women that may be bidirectional.

The participants from the population-based Canadian Multicentre Osteoporosis Study were followed from 1997 to 2013, and their Mini Mental State Examination (MMSE) and bone mineral density (BMD) scores were measured at baseline and after five and 10 years, respectively.

At baseline, over 95% of participants had normal cognition. The annual percentage change in MMSE was similar for both genders, with approximately 13% of participants experiencing significant cognitive decline after five years.

BMD declined significantly for both genders over the 10-year period, particularly in women.

In women, bone loss was significantly associated with cognitive decline in both age-adjusted and multivariable-adjusted models. Significant cognitive decline was also associated with a 68% increased risk of osteoporotic fracture.

Professor Jacqueline Center, endocrinologist at St Vincent’s Hospital, Sydney, and Senior Principal Research Fellow at the Garvan Institute of Medical Research, was one of the authors of the study. She said, ‘This is really the first longitudinal study that’s demonstrated an association over a period of time that the two conditions are happening together.’

In men, there was a similar trend but it was not statistically significant, which Professor Center hypothesised may be due to the smaller numbers of men in the study, published in the Journal of Bone Mineral Research.

Analyses suggested that cognitive decline and bone loss were associated in a bidirectional manner. Professor Center said this raised questions about why the two may coexist.

‘It could be just that the two conditions are common and they increase with age, but we adjusted for a whole lot of things, including adjusting for age, quality of life scores, other comorbidities, and even after all of that it does suggest that there’s something potentially biological going on,’ she said.

Professor Center said the study findings were a reminder to clinicians to consider the possibility of osteoporosis in a person with cognitive decline and vice versa.

‘These two conditions, which are both very common independently, may have links, and so if you’re noticing one condition [in a patient], this person could also be at increased risk of the other. Osteoporosis and fracture can be really quite devastating, with premature mortality and disability, so it’s worth, particularly in people with cognitive decline, being proactive and treating both to prevent the consequences,’ she said.
J Bone Miner Res 2021; doi: 10.1002/jbmr.4402.