Abstract
Background
Identification of lifestyle and dietary modifications which prevent or delay cognitive decline and Alzheimer's disease (AD) would confer significant social and economic benefit. Yet, there is a relative lack of large-scale longitudinal investigations of lifestyle-related factors impacting cognitive decline and AD-related pathology. The Mediterranean diet (MeDi), has been widely recognised as a healthy eating model due to its correlation with low morbidity and mortality for many chronic diseases. In the context of AD, accumulating research including our own has linked MeDi adherence with slower cognitive decline and reduced risk of AD. However, only one study to date has examined the relationship between MeDi adherence and cerebral amyloid load, with the authors reporting reduced cerebral amyloid load cross-sectionally among individuals with high MeDi adherence. There is a critical need to further explore the relationship between MeDi and brain amyloid levels using longitudinal data collected from a well-characterised ageing cohort.
Methods
We report on data collected over 36 months from cognitively healthy control participants (n=119) of the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study of Ageing. The Cancer Council of Victoria Food Frequency Questionnaire was used to generate a MeDi score for each participant at baseline. Cerebral amyloid load was quantified by Pittsburgh Compound B positron emission tomography at baseline, 18 and 36 months. The relationship between MeDi adherence and cerebral amyloid load was evaluated longitudinally using Analysis of Variance, correlations and Generalised Linear Models (age, gender, education and Apolipoprotein E ε4 carriage were included in the models).
Results
Individuals with high MeDi adherence demonstrated less cerebral amyloid accumulation over 36 months compared to those with low adherence (0.04 vs. 0.08 mean change cerebral amyloid load respectively; p=0.008).
Conclusions
To our knowledge, this is the first study to assess the relationship between MeDi adherence and cerebral amyloid burden longitudinally. Our results suggest that MeDi adherence is associated with reduced cerebral AD pathology. When our results are considered collectively with previous data linking the MeDi to slower cognitive decline, it appears that MeDi adherence warrants further investigation in the quest to delay AD onset.