Diet plays an important role in cognitive health. A recent Nutrition study evaluated the association between long-term dietary patterns from youth to adulthood and cognitive function in midlife.
Several studies have indicated that early life factors shape cognitive function in adulthood, which could be exploited to develop preventive measures against dementia and neurological deficiencies in later life. Most studies have evaluated the link between a single food or childhood nutrition that impacts cognitive function in later life. However, not many studies have examined the impact of the interactions of different dietary components on late-life cognitive function.
Dietary pattern analysis can be used to investigate the association between diet and overall health outcomes. A limited amount of evidence is available regarding the effect of overall diet pattern on cognitive function in children or adolescents. Many of these studies have reported contradictory observations. Most studies assessing the link between diet and cognitive function in adults had a short follow-up of less than ten years.
About the study
All current study participants have been recruited from the Cardiovascular Risk in Young Finns Study (YFS), a prospective cohort initiated in 1980. A total of 3,596 children from Finland between the ages of 3 and 18 participated in YFS at baseline survey. In 1980, around 50% of the cohort was randomly selected to participate in the 48 hours dietary recall interview and were re-interviewed in 1898 and 2001. It must be noted that the number of participants who attended the interview decreased in the subsequent years.
In 2007 and 2011, participants were asked to complete the food frequency questionnaire (FFQ). To investigate the relationship between long-term dietary patterns and cognitive function, participants who provided long-term dietary patterns data and information on their cognitive functions were included in this study.
Out of 3,596 participants, 2,806 were excluded due to insufficient data. Finally, 790 participants were considered, and the study cohort constituted relatively older individuals, with the majority being female. Most participants had lower systolic blood pressure (SBP) in adulthood. In addition, they had lower scores of traditional Finnish and high-carbohydrate, long-term high-carbohydrate, and red meat dietary patterns.
While high consumption of carbohydrates in early life was associated with poorer cognitive development, a healthy diet comprising vegetable and dairy product patterns was seen to lead to better cognitive function. This observation has potential clinical implications as the difference in cognitive aging was around 1.6 to 16.1 years and highlights the need to consume a healthy diet in the early years of life.
The findings documented here contribute to the literature by documenting the long-term impacts of dietary patterns in early life on adult cognitive function. While a direct comparison is not possible, previous research has shown a positive relationship between good patterns and cognitive function.
Here, a negative association was documented between cognitive function and long-term traditional Finnish patterns (characterized by a high intake of butter, milk, coffee, rye, and sausages and low consumption of berries and fruits). Plausible biological mechanisms underlying this association could include oxidative stress, inflammation, and vascular risk factors.
Strengths and limitations
The youth-onset follow-up of a large population-based representative cohort is the main strength of this study. This allowed researchers to analyze long-term dietary habits starting in early life. The repeated measurement of diet has also significantly improved data quality.
A key limitation of the study is that causality could not be established. This was mainly driven by the observational study design. Although the impacts of youth or long-term dietary interventions on adult cognitive function are still unclear, a few short-term trials focussing on a few nutrients have demonstrated benefits to cognitive function in infants and children.
In this study, the use of both the FFQ and the 48-hour dietary recall could have partially affected long-term dietary pattern scores. However, the different food items were more or less comparable across the two methods and were categorized in the same way.
Further, in line with lengthy follow-up studies, the present study had missing data owing to the loss stemming from follow-up after an extensive study period of 31 years. The participants who were lost to follow-up were more likely to be males, younger, had lower BMI, had poor school performance, and had more disadvantaged socio-economic status.
Lastly, this study did not measure youth cognitive function. Instead, youth school performance was used as a proxy, which has been shown to be strongly correlated with cognitive function in children.