Sub-cortical infarcts and the risk of falls in older people: Combined results of TASCOG and Sydney MAS studies

Background: White matter hyperintensities increase the risk of multiple falls in older people, but the effect of sub-cortical infarcts is unknown. Aims: By pooling data from two Australian population-based studies, we aimed to investigate the association between sub-cortical infarcts and multiple falls and whether this relationship, and that of white matter hyperintensities, is mediated or modified by cognitive or sensorimotor factors. Methods: Participants underwent structural magnetic resonance imaging and cognitive and sensorimotor assessments. Falls were prospectively measured over 12 months. Sub-cortical infarcts were detected visually. Total white matter hyperintensity volume was quantified using automated segmentation methods. Generalized linear models were used to examine if sub-cortical infarcts and white matter hyperintensities predicted falls. Results: The mean age of the sample (n=655) was 74·5 (standard deviation 6·7) years, 336 (51·3%) males. Overall, 114 (17·4%) had multiple falls. The majority had no sub-cortical infarcts (n=491, 75·0%), while 90 had one (13·7%), 41 had two (6·3%), and 33 had more than or equal to three sub-cortical infarcts (5·0%). The risk of multiple falls was elevated in people with more than or equal to three sub-cortical infarcts (adjusted relative risk 1·89, 95% confidence interval 1·03, 3·46) and in the highest quarter of white matter hyperintensity volume (adjusted relative risk 1·46, 95% confidence interval 1·00, 2·13). The effect of sub-cortical infarcts on falls was amplified by poorer vision (P=0·03). The effect of white matter hyperintensities was amplified by poorer vision (P=0·008), proprioception (P=0·03), and muscle strength (P=0·008). There was no modifying effect of cognitive function. Conclusions: Increasing burdens of sub-cortical infarcts and white matter hyperintensities are associated with a risk of falling. Interventions targeting sensorimotor factors along with strategies to prevent sub-cortical infarcts and white matter hyperintensities may reduce the risk of falls.