Western Diet Linked to Faster FDG‑PET Metabolic Decline in Older Women

Key Takeaways:

• In an overall cohort analysis, investigators reported no statistically significant associations between baseline Western or Prudent dietary pattern scores and longitudinal FDG-PET SUVR.
• After sex stratification, higher baseline Western diet adherence was reported to align with faster SUVR decline in women in the left fusiform gyrus, neocortex, left ventrolateral prefrontal cortex, and inferior parietal region, while corresponding associations were not reported in men.

The study included 132 community-dwelling older adults who completed a baseline food-frequency questionnaire and underwent baseline FDG-PET, with up to two follow-up scans planned at roughly 18-month intervals and a maximum follow-up of 43 months. Dietary patterns were derived from baseline dietary data using principal component analysis, yielding two patterns labeled the Western Diet and the Prudent Diet. The Western pattern reflected higher intake of sugars and saturated fats, whereas the Prudent pattern reflected higher intake of fruits, vegetables, and whole grains. Participants received adherence scores for both patterns.

Cerebral glucose metabolism was assessed using FDG-PET SUVR, and associations with baseline dietary pattern scores were analyzed using linear mixed-effects models with a random intercept for each participant. The models incorporated covariates reported by the authors: age, total energy intake, body mass index, time from dietary data collection to the baseline PET scan, and APOE genotype, and analyses were repeated after stratifying by sex. To address multiple testing, the authors report applying false discovery rate control via the Benjamini–Hochberg procedure within each model. This approach was used to estimate diet-pattern–by-time associations in regional SUVR trajectories.

In the cohort as a whole, the authors report no statistically significant associations between either dietary pattern score and longitudinal FDG-PET SUVR. They also report that the Prudent dietary pattern showed no statistically significant associations in either sex in stratified analyses.

In sex-stratified models, the authors report that among females, higher baseline Western Diet adherence was associated with faster longitudinal SUVR decline in the left fusiform gyrus (standardized β = −0.00062; SE = 0.00025; FDR-adjusted p = 0.043), neocortex (β = −0.00063; SE = 0.00026; FDR-adjusted p = 0.047), left ventrolateral prefrontal cortex (β = −0.00083; SE = 0.00032; FDR-adjusted p = 0.045), and inferior parietal region (β = −0.00344; SE = 0.00129; FDR-adjusted p = 0.033). In contrast, they report that no statistically significant negative associations between Western Diet adherence and FDG-PET SUVR were observed in males. In this dataset, the reported associations were regionally specific and female-predominant.

The authors outline several limitations for interpreting these observational findings, including a single baseline dietary assessment, variable follow-up duration and scan counts across participants, and the absence of MRI data needed for partial-volume correction. They also describe the sample size as modest, which they note may constrain detection of smaller associations and contribute to uncertainty in subgroup analyses.