Limiting sugar in the first 1,000 days of life is associated with later dementia onset, study finds

Limiting exposure to added sugar in the womb and during the first two years of life is associated with a lower risk of developing dementia decades later, according to a new study published in Neurology. By examining adults born around the end of post-World War II food rationing in the United Kingdom, researchers found that early-life sugar restriction corresponded with delayed dementia onset, healthier brain structure, and better scores on some cognitive tests in their 60s. The findings suggest that nutritional conditions during the earliest stages of human development may play a lasting role in how the brain ages.

Dementia is an umbrella term for progressive neurological conditions that impair memory, thinking, and the ability to perform everyday activities. The most common form is Alzheimer’s disease, which involves the gradual breakdown of brain cells and the buildup of abnormal proteins, followed by vascular dementia, which occurs when reduced blood flow damages brain tissue. Although lifestyle habits in middle and old age are well-known factors in cognitive decline, growing evidence points to the importance of the “first 1,000 days” of life, the developmental window spanning from conception to a child’s second birthday.

During this early period, the brain undergoes rapid growth, forming neural connections and building the structural foundation for lifelong thinking and memory. High sugar intake during pregnancy and infancy may disrupt this process by triggering inflammation or interfering with how cells respond to insulin. For instance, research covered by PsyPost in 2016 indicated that rats fed sugary drinks early in life developed changes in the hippocampus, a seahorse-shaped brain region essential for memory, that resembled the biological effects of early-life stress. In humans, observational studies have similarly linked higher maternal sugar consumption during pregnancy and breastfeeding to altered brain tissue organization in newborns and slightly lower cognitive scores in young children.

Studying how infant diets affect human brain aging is difficult because tracking people from birth into their 70s rarely happens in controlled experiments. To overcome this challenge, scientists have turned to a historical policy shift in the United Kingdom: the end of wartime sugar rationing. Introduced in July 1942 during World War II, the rationing system strictly limited added sugar and sweets to levels comparable to modern dietary guidelines while keeping overall calories and basic nutrients sufficient, unlike historical famines that caused severe starvation. When the British government abruptly ended sugar rationing in September 1953, national sugar consumption jumped by more than 50 percent, even as total calorie intake rose by only about 5 percent and other food groups remained relatively stable.

Researchers have used this sudden dietary shift to examine how early sugar limits relate to adult health, starting with a 2024 study by another team that linked rationing exposure during the first 1,000 days to lower adult rates of type 2 diabetes and high blood pressure. Extending this approach to respiratory health, a study covered by PsyPost in 2025 found that rationing exposure during pregnancy and infancy was tied to better adult lung capacity and lower rates of asthma. In the realm of mental health, a 2026 cohort study of British adults found that experiencing sugar rationing across the first 1,000 days of life was associated with a reduced preference for sweet foods and a lower risk of adult depression and anxiety.

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Building on this line of inquiry, the new study was led by Jiazhen Zheng, an assistant professor at the School of Life and Health Sciences at Shenzhen University of Advanced Technology in China, who also led the 2025 lung-health study. Zheng conducted the research at The Hong Kong University of Science and Technology (Guangzhou) alongside co-corresponding author S. W. Ricky Lee of the same institution and their colleagues, examining whether early sugar restriction also relates to long-term dementia risk, brain structure, and cognitive ability in older age.

“While growing evidence suggests that early-life nutrition can shape long-term health, remarkably little is known about whether sugar exposure during this period is associated with dementia many decades later,” Zheng told PsyPost. “We were particularly interested in addressing this knowledge gap because most dementia prevention research focuses on risk factors in middle and older age. The end of sugar rationing in the United Kingdom in September 1953 provided a unique natural experiment to investigate this question.”

The researchers analyzed data from the UK Biobank, a large health study that recruited middle-aged and older British adults between 2006 and 2010. Starting with 74,213 participants born between 1951 and 1956, the team excluded 6,582 people born outside the United Kingdom, 2,424 from multiple births such as twins or triplets, 79 adoptees, 208 people already diagnosed with dementia at recruitment, and 108 who withdrew from the project. This left a final sample of 64,737 adults who were an average of 54.6 years old at enrollment, 56.4 percent of whom were women.

Using each person’s birth date relative to the September 1953 policy change, the authors sorted participants into groups reflecting how long they experienced sugar rationing during their first 1,000 days from conception. In total, 40,963 participants experienced rationing: 10,682 were exposed in the womb only, 15,025 were exposed in the womb plus up to one year after birth, and 15,256 were exposed in the womb plus one to two years after birth. The remaining 23,774 participants were born after July 1, 1954, meaning they were conceived after rationing ended and grew up in an environment of unrestricted sugar.

The team tracked hospital admissions and death registries through July 1, 2023, to identify new diagnoses of all-cause dementia, Alzheimer’s disease, and vascular dementia. To account for other differences between the groups, the statistical models controlled for age, sex, race, birthplace, birth month, inflation-adjusted food prices, average national fat intake at birth, maternal smoking, breastfeeding, and parental dementia history. The researchers also adjusted for adult household income, neighborhood socioeconomic status, smoking, alcohol consumption, physical activity, and chronic illnesses such as heart, kidney, and liver disease.

In addition to tracking dementia diagnoses, the authors examined a subset of more than 7,500 participants who underwent magnetic resonance imaging (MRI) brain scans at an average age of 61.8 years, alongside roughly 6,400 to 20,600 participants who completed computerized cognitive assessments. These brain scans measured total brain volume, gray matter (the outer layer of brain tissue rich in nerve cell bodies), white matter (the deeper nerve fibers that connect different brain regions), the hippocampus, and white matter hyperintensities, which are bright spots on a scan that indicate small blood vessel damage and tissue wear.

Building on the 2024 research linking rationing to metabolic and vascular health, the team also tested whether adult type 2 diabetes and high blood pressure explained the link between early sugar restriction and dementia, and they checked two conditions considered unlikely to be affected by early sugar intake, type 1 diabetes and melanoma (a form of skin cancer), as negative controls.

Over the follow-up period, 504 out of 23,774 unexposed participants (about 2.1 percent) were diagnosed with all-cause dementia, including 227 cases of Alzheimer’s disease (about 1.0 percent) and 178 cases of vascular dementia (about 0.75 percent). In raw numbers, the rationed groups had slightly higher dementia rates, largely because they were born earlier and were more than two years older on average than the unexposed group, with 251 dementia cases among the 10,682 people rationed only in the womb (about 2.3 percent), 388 cases among the 15,025 people rationed through age one (about 2.6 percent), and 456 cases among the 15,256 people rationed for one to two years (about 3.0 percent). Once the researchers adjusted for age and other background variables, the rationed groups showed a lower risk of developing dementia at any given age, though the association for those exposed only in the womb was smaller and not statistically significant.

Compared with adults who never experienced rationing, those exposed to sugar rationing in the womb plus their first year of life had a 21 percent lower hazard (the rate at which new cases appear at a given age) of developing all-cause dementia and a 23 percent lower hazard of developing Alzheimer’s disease. The association was slightly stronger for those exposed in the womb plus one to two years after birth, who showed a 23 percent lower hazard of all-cause dementia and a 28 percent lower hazard of Alzheimer’s disease.

For vascular dementia, the estimates pointed in a similar direction, though the results were not statistically significant. Looking at the timing of diagnoses, experiencing rationing from conception through ages one to two was associated with delaying the onset of all-cause dementia by 2.55 years, Alzheimer’s disease by 2.87 years, and vascular dementia by 2.49 years.

“The magnitude of the associations was particularly noteworthy,” Zheng said. “These are population-level estimates rather than predictions for any individual, but even modest shifts in dementia occurrence could have meaningful public health implications given the growing global burden of the disease.”

The results were less robust in one additional analysis. When the researchers accounted for the possibility that participants would die of other causes before developing dementia, rationing exposure was still linked to a roughly 15 percent lower likelihood of all-cause dementia, but the associations with Alzheimer’s disease and vascular dementia were no longer statistically significant.

The link between early sugar rationing and dementia was stronger in women than in men, which the authors noted might relate to biological differences in how female neural circuits respond to early nutritional environments. The results held steady regardless of whether participants carried genetic variants of the apolipoprotein E gene that heighten Alzheimer’s risk. Mediation analyses indicated that lower rates of adult type 2 diabetes and high blood pressure accounted for 18.0 percent and 11.6 percent of the association, respectively, or 25.5 percent when combined, while birth weight accounted for just 2.7 percent. As expected, rationing exposure showed no association with type 1 diabetes or melanoma, and the primary dementia patterns were supported by a validation analysis in an independent British aging study, with an American cohort serving as a comparison group.

The brain imaging and cognitive test results aligned with the clinical dementia findings. Compared with the unexposed group, participants who experienced early-life sugar rationing had larger total gray matter volumes, averaging 618.9 cubic centimeters versus 618.5 cubic centimeters (an adjusted increase of 3.27 cubic centimeters), and smaller volumes of white matter hyperintensities, averaging 3.72 cubic centimeters versus 3.84 cubic centimeters (an adjusted reduction of 0.64 cubic centimeters).

Rationed participants also performed better on tests of complex processing speed, verbal and numerical reasoning, nonverbal pattern reasoning, and a timed test of visual attention that involves connecting numbered circles in order. Differences in total brain volume, white matter volume, hippocampal size, working memory, verbal memory, and a harder version of the connect-the-dots test that requires switching between numbers and letters were not statistically significant. These differences were modest: the gray matter difference amounted to about half a percent of total gray matter volume, and the cognitive differences were similarly small.

“What struck us most was how strongly early-life nutritional exposure appeared to be associated with brain health more than half a century later,” Zheng explained. “Beyond dementia diagnoses, we also observed favorable differences in brain MRI measurements, including greater gray matter volume and fewer white matter hyperintensities, alongside better performance on certain cognitive tests. The convergence of these findings across clinical, structural, and cognitive outcomes was especially interesting and suggested that the associations might reflect broader processes of brain aging.”

These results are consistent with research covered by PsyPost in December 2025, which tracked broad diet quality across the lifespan starting at age four rather than isolating sugar restriction during the first 1,000 days of life, and similarly found that healthier early nutritional habits were associated with better cognitive performance and a lower risk of late-life dementia. They also align with another study covered by PsyPost in November 2025, which examined how chronic sugar consumption caused memory impairment and Alzheimer’s-related brain pathology in adult rats rather than how early-life sugar restriction affects long-term dementia risk in humans, yet similarly linked high sugar exposure to neurodegenerative decline.

“Our findings suggest that the nutritional environment during pregnancy and early childhood may have consequences for brain health that extend across an entire lifetime,” Zheng told PsyPost. “The key message is not that people should eliminate sugar entirely, but rather that limiting excessive added sugar during these sensitive developmental periods may be beneficial. Importantly, our findings demonstrate associations, not definitive causation.”

As with all research, there are some caveats to consider when interpreting these findings. Because this was an observational study that relied on birth dates during a historical policy change, the researchers did not have direct measurements of how much sugar individual pregnant mothers or infants actually consumed. Although national surveys confirm that household sugar purchases surged right after September 1953, personal eating habits within both the rationed and unrationed groups likely varied from family to family. Because exposure was determined entirely by birth date, the rationed participants were also older, so the findings depend on statistical adjustments for age; the authors checked this by confirming that dementia risk did not drift among never-rationed participants born at different times after the policy ended.

“One important distinction is that our study does not prove that reducing sugar intake in infancy directly prevents dementia,” Zheng noted. “Other dietary, social, or environmental differences associated with the rationing period may also have influenced the results. Furthermore, our findings should not be interpreted as advocating extremely restrictive diets during pregnancy or infancy; adequate and balanced nutrition remains essential for healthy development.”

Another consideration is the age and makeup of the study population. Because participants were born in the early to mid-1950s, they were only in their late 60s and early 70s by the end of the tracking period in 2023, meaning the study primarily captured relatively early cases of dementia rather than diagnoses occurring in the 80s and 90s.

In addition, the UK Biobank consists of volunteers who survived into middle age and tend to be healthier, wealthier, and predominantly white (over 96 percent of this sample), which may limit how well the findings apply to more diverse or disadvantaged populations. The authors suggest that future randomized trials testing practical nutritional counseling to limit added sugars during pregnancy and infancy could help establish how early dietary habits shape brain development and long-term cognitive resilience.

“We hope to better understand the biological mechanisms linking early-life nutrition with brain aging and neurodegenerative diseases,” Zheng said. “In this study, type 2 diabetes and hypertension together statistically accounted for approximately one-quarter of the observed association, suggesting that metabolic and vascular health may play a role. Future research should examine additional biological pathways, clarify the most sensitive developmental windows, and determine whether these findings can be replicated in other populations with more detailed dietary information. Ultimately, we hope this work will help inform evidence-based nutritional recommendations across the life course.”

“I believe one of the broader implications of our work is that dementia prevention may need to be considered from a much earlier life-course perspective,” Zheng added. “We often think of dementia as a disease of old age, but some of the factors associated with vulnerability or resilience may originate decades before symptoms appear. Understanding these early influences could open new opportunities for preventive research and public health strategies.”

The study, “Association of Sugar Restriction in Utero Through Age 2 Years on Dementia Risk Later in Life,” was authored by Jiazhen Zheng, Gregory Y.H. Lip, Zhuoni Zhang, and S. W. Ricky Lee.