This study is undoubtedly a further advance in the knowledge of the negative effect of ultra-processed foods on health, in this case on cognitive aspects.   

It is the first study to link the consumption of ultra-processed foods with cognitive impairment. The assessment of cognitive impairment in this research was carried out through tests assessing memory and executive functions. Changes in these tests were assessed over time, with a follow-up of 6-10 years.   

The results suggest that people with higher consumption of ultra-processed foods have faster cognitive decline over time. Specifically, they report a 28% faster rate of decline compared to those who consumed less ultra-processed foods. Since intact cognitive function is key to successful ageing, these results highlight the need to reduce consumption of ultra-processed foods to maintain long-term cognitive health.   

The study is original and based on a large but not fully representative sample of the population, as it only includes adult civil servants. The methodology used is good and takes into account the main confounding factors, although there are some limitations to the study, such as the fact that dietary data were only collected at the beginning of the study and not throughout the follow-up, thus ignoring possible changes in dietary habits that the subjects may have had. 

The study is very good, with a very large sample size and a good design. It is novel because there are very few studies on the effects of ultra-processed foods on cognition. There are no major limitations. The confounding variables are correct.