Early-life sugar restriction tied to lower dementia risk

Clinical takeaway: This strengthens the case for holding down added sugar in pregnancy and early childhood, though it stops well short of proving that doing so prevents dementia.

Most dementia-prevention advice targets midlife and later, focusing on blood pressure, hearing, vision, diet, activity. This study pushes the window back to the very start, before birth through age two. Using the abrupt end of UK sugar rationing in 1953 as a natural experiment, researchers compared adults whose earliest diet was sugar-limited against those who came just after, then tracked them for dementia. The design strengthens the case that early sugar exposure, not just later habits, tracks with poor brain aging.

Sugar intake in early childhood routinely runs well above what guidelines recommend. Sugar was rationed in the UK during and after World War II, then became widely available again in 1953, an abrupt shift that sets up this study. Those early exposures shape metabolism, weight, and vascular health for decades, all pathways that feed into dementia risk. With cases climbing as populations age and treatment options few, any modifiable exposure could be helpful.

People whose earliest diet was sugar-limited had a 21% lower risk of dementia if the restriction covered gestation through the first year, and 23% lower if it extended through age two. In absolute terms the gap was modest: dementia developed in about 2.1% of the sugar-rationed groups versus 2.6% of those born after rationing ended. Among those who did develop dementia in the sugar-rationed group, onset also came about 2.6 years later.

A brain-imaging subgroup pointed in the same direction. The sugar-rationed group had higher total gray matter volume and fewer white matter hyperintensities, a marker of small-vessel damage. Diabetes and hypertension developing in adulthood jointly accounted for about a quarter of the sugar-dementia link, suggesting the effect runs largely, but not entirely, through familiar metabolic and vascular pathways.

The analysis drew on 64,737 UK Biobank participants born in the years bracketing the end of sugar rationing in September 1953. Researchers sorted them by how much of their first 1,000 days fell under rationing, in utero only, in utero plus year one, or in utero plus years one to two, and compared each against adults born just after, when rationing had ended. Dementia was captured from linked medical records over as much as 15 years of follow-up.

A natural experiment can show the association but can't tell a clinician whether actively cutting added sugar in pregnancy and infancy changes anything. For now it reinforces existing added-sugar guidance for families rather than justifying a new one.

"Limiting added sugars during pregnancy and infancy may be one beneficial step that families and communities can take, but further research is needed to better understand how these early exposures influence dementia risk and to guide public health strategies," said Jiazhen Zheng, PhD, of The Hong Kong University of Science and Technology in Guangzhou, China.

Source: Zheng J, et al. (2026 July 29) Neurology. Association of Sugar Restriction in Utero Through Age 2 Years on Dementia Risk Later in Life