Anti-Inflammatory Diet Linked to Lower Dementia Risk, Better Brain Health in Patients With Cardiometabolic Diseases

Patients with cardiometabolic diseases (CMDs) who follow an anti-inflammatory diet have better brain health and a lower risk of dementia than those with a proinflammatory diet, according to a study published in JAMA Network Open.

Past research linked CMDs, like heart disease, stroke, and type 2 diabetes, to increased dementia risk. Meanwhile, inflammation has been associated with the pathophysiologic characteristics of both dementia and CMDs, offering a potential explanation for the increased dementia risk among those with CMDs.

Dietary intake can influence the body's systemic inflammatory processes.² Past research determined that consuming more vegetables, fruits, whole grains, and fish lowers inflammatory biomarker levels. Lower dietary inflammatory potential, as determined by the Dietary Inflammatory Index (DII), has been linked to better cognitive function, more favorable MRI markers of brain aging, and a lower risk of dementia and CMDs.³

However, it is unknown how much an anti-inflammatory diet may support brain and cognitive health among those with CMDs.¹ Using a joint effect analysis, the researchers examined the role of both CMDs and dietary inflammatory potential in dementia risk and MRI markers of neurodegenerative and vascular brain damage.

To do so, they used the UK Biobank, an ongoing longitudinal study that includes over 500,000 adults between the ages of 40 and 70.⁴ All patients had a baseline examination between March 13, 2006, and October 1, 2010, and a subset underwent a brain MRI scan between May 2, 2014, and March 13, 2020.

As for CMDs, type 2 diabetes was determined based on medical records, biochemical measures, the use of glucose-lowering medications, and self-reported diabetes history.¹ Similarly, stroke and heart disease diagnoses were determined based on medical records and self-reported medical history. Patients were dichotomized as CMD-free or having CMDs based on their total number of CMDs.

Like CMDs, dementia diagnoses were based on information from inpatient records, death registers, and self-reported medical history. Additionally, the researchers examined patients’ total brain volume (TBV), gray matter volume (GMV), hippocampal volume (HV), white matter volume (WMV), and white matter hyperintensity volume (WMHV) collected from the brain MRI scans.

Based on data collected using the Oxford WebQ dietary assessment, the researchers calculated each patient's DII score. The DII scores were based on 45 inflammation-related dietary parameters, each assigned an inflammatory effect score (IES), negative for anti-inflammatory and positive for proinflammatory. The DII score was the sum of each dietary parameter’s IES multiplied by the participant’s central consumption percentile.

Only the parameters with available information were used, so the DII score was based on 31 parameters and ranged from −6.7 to 5.2 points. Based on their scores, the researchers placed patients into one of the following categories: anti-inflammatory diet (≤ −1.5 points), neutral diet (> −1.5 to < 0.5 points), or proinflammatory diet (≥ 0.5 points).

The researchers limited the study population to participants 60 years or older who completed a dietary questionnaire. After further exclusions, the researchers analyzed 84,342 patients, including 8917 from the neuroimaging subsample. The study population consisted of mostly female patients (51.2%; n = 43,220), and the mean (SD) age was 64.1 (2.9) years.

Also, 14,079 (16.7%) patients had at least 1 CMD; they were more likely to be male, be older, have a lower socioeconomic status, and identify as Asian, Black, or multiracial. Conversely, those in the neuroimaging subsample (n = 8917) were younger with a higher socioeconomic status and a more favorable vascular risk factor profile.

During the follow-up period (median [IQR], 12.4 [11.8-13.1] years), 1559 (1.9%) patients developed dementia. The presence of CMDs was associated with an 81% increased dementia risk (HR, 1.81; 95% CI, 1.61-2.04) while having an anti-inflammatory diet was associated with a 21% lower dementia risk (HR, 0.79; 95% CI, 0.68-0.91). However, dementia risk was 31% lower (HR, 0.69; 95% CI, 0.55-0.88; P = .003) among those with CMDs and an anti-inflammatory diet than those with CMDs and a proinflammatory diet.

Based on the neuroimaging subsample, CMDs were associated with significantly smaller GMV, HV, WMV, and TBV, but significantly larger WMHV. In comparison, having an anti-inflammatory diet was associated with larger GMV, WMV, and TMV, and smaller WMHV.

Therefore, the joint analysis reported that patients with CMDs and an anti-inflammatory diet had significantly larger GMV (β = −0.15; 95% CI, −0.24 to −0.06 vs β = −0.27; 95% CI, −0.38 to −0.16) and significantly smaller WMHV (β = 0.05; 95% CI, −0.04 to 0.14 vs β = 0.16; 95% CI, 0.05-0.27). In other words, patients with CMDs and anti-inflammatory diets had better brain health and less brain damage than those with CMDs and proinflammatory diets.

The researchers acknowledged their study’s limitations, including the UK Biobank's healthy volunteer bias. This, especially in the neuroimaging subsample, could have limited the generalizability of their findings and contributed to an underestimation of the observed associations. Despite their limitations, the researchers expressed confidence in their findings. 

“Together, these results highlight an anti-inflammatory diet as a modifiable factor that may support brain and cognitive health among people with CMDs,” the authors concluded.

References

1. Dove A, Dunk MM, Wang J, Guo J, Whitmer RA, Xu W. Anti-inflammatory diet and dementia in older adults with cardiometabolic diseases. JAMA Netw Open. 2024;7(8):e2427125. doi:10.1001/jamanetworkopen.2024.27125
2. Galland L. Diet and inflammation. Nutr Clin Pract. 2010;25(6):634-640. doi:10.1177/0884533610385703
3. Shivappa N, Steck SE, Hurley TG, Hussey JR, Hébert JR. Designing and developing a literature-derived, population-based dietary inflammatory index. Public Health Nutr. 2014;17(8):1689-1696. doi:10.1017/S1368980013002115
4. Sudlow C, Gallacher J, Allen N, et al. UK Biobank: an open access resource for identifying the causes of a wide range of complex diseases of middle and old age. PLoS Med. 2015;12(3):e1001779. doi:10.1371/journal.pmed.1001779