Lifestyle for brain health and cognitive functioning in midlife to early late-life New Zealanders: Utility of the LIBRA index

Abstract

Objectives: There is enormous potential to improve brain health and reduce the risk of cognitive decline and dementia based on modifiable risk factors. The Lifestyle for Brain Health (LIBRA) index was developed to quantify modifiable dementia risk or room for brain health improvement. The objective of the study was to investigate the utility of the LIBRA index in relation to cognitive functioning in a midlife to early late-life sample of New Zealanders.

Methods: A subsample (n = 1001) of the longitudinal New Zealand Health, Work and Retirement (NZHWR) study completed face-to-face cognitive assessments using the 'Kiwi' Addenbrooke's Cognitive Examination-Revised (ACE-R) in 2010 and again in 2012, in addition to completing biennial NZHWR surveys on socioeconomic, health and wellbeing aspects. The LIBRA index was calculated incorporating information on 8 out of 12 modifiable health and lifestyle factors for dementia. Unadjusted and adjusted regression models and mixed effects models were used to inspect associations of LIBRA with cognitive functioning, cognitive impairment, and cognitive decline.

Results: The analytical sample (n = 881 [88.0%], after considering exclusion criteria and missing data) had a mean age of 63.1 (SD = 6.5) years, 53.3% were female, 26.2% were Māori, and 61.7% were highly educated. Higher LIBRA scores (indicating higher modifiable dementia risk) were associated with lower cognitive functioning (B = -0.33, 95% CI = -0.52;-0.15, p < 0.001) and a higher likelihood of cognitive impairment (OR = 1.22, 95% CI = 1.04; 1.42, p = 0.013), but did not predict cognitive decline over 2 years (B = -0.03, 95% CI = -0.22; 0.16, p = 0.766), adjusted for age, age², gender, education, and ethnicity.

Conclusions: The LIBRA index indicated promising utility for quantifying modifiable dementia risk in midlife and early late-life New Zealanders. For local use, refinement of the LIBRA index should consider cultural differences in health and lifestyle risk factors, and further investigate its utility with a wider range of modifiable factors over a longer observation period.

Keywords: LIBRA; New Zealand; cognitive functioning; cohort study; dementia; lifestyle; prevention; risk reduction.