On 12 March, an international team of researchers published an article on an investigation about midlife diet and subsequent risk for dementia in the journal JAMA. The researchers used information from 8,225 participants who took part in the observational study that started in 1985. Out of all participants, with available follow-up information, 344 developed dementia over the course of the study. In order to see if a healthier diet coincides with lower rates of dementia, the scientists derived an Alternative Health Eating Index (AHEI) from food frequency questionnaires the participants were asked to fill out during follow-up examinations that took place approximately every five years throughout about twenty-five years.
For their analyses, the researchers leveraged on information from three time points for which the AHEI were calculated (1991-1993, 1997-1999, and 2002-2004). Participant information was grouped for each time point into a tertile depending on how healthy the person’s diets were. The team then looked at the incidence of dementia by participant group and were unable to find a significant correlation between a healthy midlife diet and incident dementia.
The researchers nevertheless explained that it remains unclear whether a healthy diet plays a role in influencing cognitive outcomes in a combination with other behaviours that promote health as well as that their study does not warrant about the influence of diet in subgroups at increased risk for dementia. Lastly, the team also underlined that as it is the case for all observational studies, that it is impossible to rule out all factors that might have had an influence but were not included in the analyses.