The moderating effect of diet on the relationship between depressive symptoms and Alzheimer’s disease-related blood-based biomarkers

Associations between mental health, diet, and risk of Alzheimer’s disease highlight the need to investigate whether dietary patterns moderate the relationship between symptoms of depression and anxiety, and neurodegeneration-related blood-based biomarkers. Cognitively unimpaired participants (n = 89) were included from the Australian Imaging, Biomarkers and Lifestyle study (mean age 75.37; 44 % male). Participants provided dietary, depressive and anxiety symptom data, and had measurement of blood-based biomarkers. Dietary pattern scores (Mediterranean diet (MeDi), Dietary Approaches to Stop Hypertension diet (DASH), and Western diet) were generated. Moderation and simple slope analyses were employed. In males with mean and below mean MeDi adherence, depressive symptoms were associated with higher neurofilament light (NfL) levels. In Apolipoprotein E ε4 non-carriers with lower than mean and mean MeDi adherence, depressive symptoms were associated with higher NfL and Aβ40 levels. No associations were observed between DASH and Western diets and neurodegeneration-related biomarkers. MeDi adherence is potentially a moderator of the relationship between depressive symptoms and neurodegeneration-related blood-based biomarkers, with sex- and genotype-specific approaches important to consider within this relationship. [Display omitted] •Examined diet's role in depression and neurodegeneration risk.•Included 89 cognitively healthy older adults, mean age 75.37 years.•Males with low MeDi adherence showed higher NfL with depressive symptoms.•High-risk individuals with depression and poor MeDi had elevated biomarker levels.•MeDi may moderate the depression and neurodegeneration relationship.