Med Diet Adherence Associated with Lower Dementia Risk

A long-term, large-scale study pub­lished by BMC Medicine pro­vided fur­ther evi­dence that adher­ence to the Mediterranean diet is asso­ci­ated with lower demen­tia risk.

The results showed that par­tic­i­pants with the high­est adher­ence to the Mediterranean diet lower such risk by up to 23 per­cent. A lower adher­ence might still yield some ben­e­fi­cial effects.

A research team from Newcastle University and other United Kingdom aca­d­e­mic insti­tu­tions assessed the impact of fol­low­ing the Mediterranean diet on 60,298 peo­ple with a fol­low-up period of more than nine years. The size and dura­tion of the trial make it one of the most exten­sive stud­ies ever con­ducted in this area.

“There have been a num­ber of pre­vi­ous stud­ies on the sub­ject,” Oliver Shannon, a co-author of the study and researcher at Newcastle University’s Population Health Sciences Institute, told Olive Oil Times.

“Generally, they have been small stud­ies and did not have many demen­tia cases, fac­tors that lim­ited their sta­tis­ti­cal power to detect the pos­si­ble asso­ci­a­tion between the Mediterranean diet and demen­tia,” he added.

The researchers accessed the infor­ma­tion from the U.K. Biobank data­base, an ongo­ing cohort study of more than 500,000 par­tic­i­pants. The data­base is con­sid­ered a cru­cial source for inves­ti­gat­ing dis­eases that develop in mid­dle and older age.

By apply­ing stan­dard inves­ti­ga­tion meth­ods com­monly used in long-term cohort stud­ies, U.K. sci­en­tists could iden­tify indi­vid­u­als whose data were of inter­est for the study, includ­ing Mediterranean diet adher­ence.

Eight hun­dred eighty-two cases of demen­tia were reported dur­ing the 9.1‑year fol­low-up period in the sam­ple group, which included indi­vid­u­als with an aver­age age of 63.8 years.

Their dietary habits, body mass index, socioe­co­nomic sta­tus, edu­ca­tion, sleep dura­tion and phys­i­cal activ­ity level were among the indexes con­sid­ered by the research.

The extended fol­low-up pro­vides researchers with a more reli­able data set to study. Usually, patients who are in the early stages of devel­op­ing demen­tia switch to a health­ier diet as a con­se­quence of that con­di­tion.

“That makes it more chal­leng­ing for these kinds of stud­ies as there is a poten­tial issue of reverse causal­ity,” Shannon said. ​“But if you can track the dietary habits for a long time, that mit­i­gates the issue of reverse causal­ity, as you can look at how their dietary habits were before [the demen­tia onset] and how they devel­oped.”

Therefore, the researchers mea­sured the inci­dence of demen­tia in each of the three groups into which the study sub­jects were divided, iden­ti­fied by low, mod­er­ate or high adher­ence to the Mediterranean diet.

“If we look at peo­ple with the low­est adher­ence to the Mediterranean diet, for every 1,000 peo­ple we have seen, 17 of them develop demen­tia dur­ing the fol­low-up period,” Shannon said. ​“In the higher Mediterranean diet intake group, instead, only 12 indi­vid­u­als per 1,000 devel­oped demen­tia.”

In the study, the researchers high­lighted how higher Mediterranean diet adher­ence was found among women with healthy body mass index val­ues, higher edu­ca­tional lev­els and a higher level of phys­i­cal activ­ity com­pared to the group with lower adher­ence.

The study also inves­ti­gated how indi­vid­u­als with a genetic pre­dis­po­si­tion for demen­tia respond to adopt­ing the Mediterranean diet.

“That is some­thing that very lit­tle pre­vi­ous research has ever looked into,” Shannon said. ​“We were inter­ested to see if the impact of the Mediterranean diet dif­fered in indi­vid­u­als with dif­fer­ent genetic pro­files.”

“We know that there are cer­tain genes which might make indi­vid­u­als more likely to develop demen­tia or cer­tain vari­ants of those genes,” Shannon said.

For exam­ple, indi­vid­u­als who carry the APOE gene and its allele APOE4 are con­sid­ered sig­nif­i­cantly more at risk of devel­op­ing demen­tia.

In their study, sci­en­tists used a poly­genic risk score to com­bine a com­plete set of genetic infor­ma­tion poten­tially related to demen­tia onset and used it to pro­file the sub­jects involved in the study.

“That allowed us to explore if the impact of the Mediterranean diet would be dif­fer­ent for peo­ple car­ry­ing a high genetic risk and peo­ple with a low genetic risk,” Shannon said.

“What we found is that irre­spec­tive of the degree of the genetic risk, there is a ben­e­fi­cial pat­tern to adopt­ing the Mediterranean diet,” he added. ​“The good news is that even if you have a high genetic risk of devel­op­ing demen­tia, you could still ben­e­fit from dietary changes.”

According to Alzheimer’s Research, a char­ity, approx­i­mately 944,000 peo­ple in the coun­try have demen­tia. About 67 mil­lion peo­ple live in the U.K. Statistics show that in the over-65 age group, one per­son out of 11 has demen­tia.

The inci­dence of demen­tia in the coun­try is expected to grow con­sid­er­ably over time, ris­ing from one mil­lion patients in 2030 to 1.6 mil­lion expected by 2050. According to the research insti­tute, increas­ing life expectancy is the dri­ving force behind these ris­ing fig­ures.

Separate research pub­lished in The Lancet last year found demen­tia cases are expected to triple glob­ally by 2050, ris­ing to more than 153 mil­lion peo­ple.

The sci­en­tists said the next steps of the research would inves­ti­gate whether the Mediterranean diet can be used as a tool for inter­ven­tion against demen­tia. Such a study would assess the demen­tia out­comes of groups of peo­ple fol­low­ing dif­fer­ent diets.

“Rather than just look­ing at the inter­ac­tions and the asso­ci­a­tions, we hope in the com­ing years to be research­ing whether it is pos­si­ble to inter­vene with the Mediterranean diet to help cur­tail demen­tia,” Shannon con­cluded.

• Alzheimer’s Research U.K.