A large-scale, long-term study has found no link between Mediterranean-like diet adherence and reduced dementia risk.
The study, published in Neurology, followed nearly 30,000 people for about 20 years. The researchers’ goal at the outset was to determine whether diet could reduce the risk of developing a range of cognitive disorders.
One challenge for such a long study interval is that dietary habits could not be followed longitudinally over the period to assess potential changes in dietary habits. Thus, the results are challenged by potential confounders.
The study found that following conventional dietary recommendations or a modified Mediterranean diet (where dietary fat comprised olive oil and vegetable oil due to low consumption of the former in Sweden) was not significantly associated with a reduced risk of developing all-cause dementia, Alzheimer’s disease or vascular dementia.
The researchers added that the results were similar when excluding participants who developed dementia within five years and those with diabetes.See Also:Health News
“Dementia cases are expected to triple during the next 30 years, highlighting the importance of finding modifiable risk factors for dementia,” the researchers wrote.
The scientists based their results on the dietary habits of more than 28,000 residents in the Swedish city of Malmö who were born between 1923 and 1950 and had participated in the prospective “Swedish population-based Malmö Diet and Cancer Study” between 1991 and 1996, with a follow-up for incident dementia until 2014.
During that period, nearly 7 percent of the participants developed different types of dementia. No specific diet was associated with the presence of Alzheimer’s disease markers in affected patients.
“Dietary habits were assessed with a seven-day food diary, detailed food frequency questionnaire and one-hour interview,” the researchers wrote.
Previous studies have demonstrated the benefit of following the Mediterranean diet on cognition and brain function, especially in older adults.
A 2021 study published in Clinical Nutrition found that participants experienced “small-to-moderate” improvements in several cognitive domains after following the Mediterranean diet for three years compared with a control group. Improvements included spatial, visual and verbal memory improvements and attention span.
In another 2022 study from Harvard University, researchers found that following a green Mediterranean diet low in red meat intake protected the brain from attenuated age-related brain atrophy.
Still, the new Swedish research confirmed findings from two studies conducted by the American Medical Association in 2019, which included thousands of individuals but had found no evidence that diet, including the Mediterranean diet, affects the risk of developing dementia.
Commenting on the Swedish study, Nils Peters, a neurologist at the Klinik Hirslanden in Switzerland, and Benedetta Nacmias, an associate professor of neurology at the University of Florence, Italy, observed that “diet as a singular factor may not have a strong enough effect on cognition, but is more likely to be considered as one factor embedded with various others, the sum of which may influence the course of cognitive function.”
Other factors include regular exercise, smoking, alcohol consumption and stress.
“One challenge for such a long study interval is that dietary habits could not be followed longitudinally over the period to assess potential changes in dietary habits,” Peters told Live Science.
“Thus, the results are challenged by potential confounders, such as changes of dietary habits, lifestyle changes or newly co-occurring medical conditions over time,” he concluded.