Mediterranean Diet Foods are Associated with Plasma Biomarkers of Alzheimer’s Disease and Related Dementias

Abstract Background The Mediterranean diet (MeDi) has been reported as preventative against cognitive decline and AD (Berti et al. 2018, Neurology ) and associated with decreased brain atrophy (Staubo et al. 2016, Alz&Dem ). Here, we examined associations between specific foods in the MeDi and plasma biomarkers of ADRD in the Indiana ADRC (IADRC) sample. Method Plasma ptau181 and neurofilament light (NfL) from 177 individuals (57 CN/53 SCD/40 MCI/27 AD), and amyloid beta (Aβ) 42 and 40, total tau, and glial fibrillary acidic protein 2 (GFAP) from 161 individuals (49 CN/51 SCD/35 MCI/26 AD) were generated using SIMOA assays at IU or Gothenburg, Sweden. Participants completed a self‐report diet questionnaire at the IADRC, which was coded into high, medium, or low intake groups for each food. We performed linear regressions to test the association of the food groups and total MeDi score to ADRD plasma biomarkers, covaried for age, sex, diagnosis, and SIMOA batch. Result Higher intake of red meat (p = 0.014), grains (p = 0.029), and beans (p = 0.009) significantly correlated with higher plasma NfL. Fast food also followed this trend (p = 0.053). Higher intake of olive oil showed a trend toward lower pTau181 (p = 0.055). Higher intake of grains was associated with higher Aβ42 (p = 0.038), while higher intake of sweets was associated with lower levels of Aβ40 (p = 0.016). There were no significant associations with specific foods and the Aβ42/40 ratio after covarying. Conclusion As expected, olive oil was associated with decreased pTau181, while higher intake of red meat and fast foods were associated with increased levels of NfL. Contrary to the MeDi hypothesis, beans and grains contributed to higher NfL. While grains and sweets influenced individual levels of Aβ42 and Aβ40 respectively, these individual levels are less understood than the ratio and require further investigation. Previous studies have shown correlation of high carbohydrate and sugar intake with smaller entorhinal cortex thickness, and legumes with larger cortical thickness. A limitation is that specific types of beans and grains consumed were not collected. Further studies will investigate diagnostic group, ethnoracial, socioeconomic, and BMI effects, as well as the role of the gut microbiome.