Diet quality linked to lower dementia risk in older Swedes

Older adults with blood signs tied to higher dementia risk appeared to have a lower chance of developing the condition when their diets were healthier, according to research published in JAMA Network Open. The findings add evidence that lifestyle may still matter after early biological changes linked to dementia have begun, though the study cannot prove diet caused the lower risk.

The study, led by Anja Mrhar and colleagues and described by the researchers in The Conversation, followed nearly 1,900 adults aged 60 and older in Sweden for as long as 15 years. None had dementia when the study began. Over the follow-up period, 240 participants developed dementia.

Researchers assessed participants’ diets several times and compared eating patterns with later dementia diagnoses. They also examined blood biomarkers associated with Alzheimer’s disease processes, nerve cell injury and biological stress in the brain.

Less inflammatory diets stood out

Mrhar and colleagues reported that healthier eating patterns were generally linked to lower dementia risk. That association was also seen among people whose blood markers suggested higher biological risk, including markers related to Alzheimer’s-type changes.

The strongest and most consistent result in the higher-risk group involved the inflammatory potential of the diet, according to the researchers. Among people with elevated risk-related biomarkers, diets rated as less likely to promote inflammation were associated with up to a 30% lower relative risk of dementia.

The researchers cautioned that a relative risk reduction compares groups and does not predict whether any one person will or will not develop dementia. They also noted that the work was observational, meaning it can identify associations among diet, biomarkers and dementia risk but cannot establish cause and effect.

In this research area, a lower-inflammatory diet generally includes more vegetables, fruits, whole grains, legumes, tea and coffee, according to the authors. It generally includes fewer foods such as red and processed meat, refined grains and sugary drinks.

Different diet scores showed different patterns

The team evaluated diet quality in three ways: adherence to a Mediterranean-style diet, alignment with general healthy eating guidelines, and the likely inflammatory effect of the overall diet. Mrhar and colleagues said this allowed them to compare whether different measures of diet quality mattered more for people with different biological profiles.

The Mediterranean-style and general healthy-diet scores were more strongly linked to lower dementia risk among people with lower biomarker levels, the researchers reported. They said those patterns may still be relevant for people at higher biological risk, but the results suggest different aspects of diet quality may relate to dementia risk through different routes.

Inflammation is part of the body’s response to infection and injury, the authors wrote. The concern for brain health is long-running, low-grade inflammation, which scientists are studying as a possible contributor to brain aging and dementia through immune activity, blood vessels, insulin resistance and heart health.

The researchers cited several strengths of the study, including repeated diet measurements, a long follow-up period, careful dementia identification and comparisons of multiple dietary patterns in the same group. They also listed limitations: diet was measured by questionnaire, and the participants came from one urban area in Sweden and were relatively healthy and well educated on average.

Mrhar and colleagues said the takeaway should be measured. A healthy diet does not remove dementia risk, which is also shaped by age, genes, cardiovascular health, social conditions and chance. Their findings suggest diet may remain relevant to brain health even when blood markers already point to higher biological risk.

This story draws on original reporting from Medical Xpress.