Researchers from the Hong Kong University of Science and Technology analysed data from nearly 65,000 participants in the UK Biobank.
According to the BBC, the team compared people who were infants before and after Britain's sugar rationing ended in 1953.
Following the end of rationing, average daily sugar consumption almost doubled, rising from about 41 grams to 80 grams.
The BBC also reported that earlier research has linked this increase in sugar consumption to a higher risk of type 2 diabetes and high blood pressure later in life.
Also read: Researchers identify a possible cause of muscle pain linked to statins
Results require caution
The study was published in the journal Nature.
The researchers stressed that it was an observational study, meaning it can identify associations but cannot prove that sugar directly caused the differences seen between the groups.
According to the BBC, independent experts said many other factors could have affected participants' health over their lifetimes. The researchers also did not have precise records of each person's individual sugar intake.
Possible link
The study found that people who were younger than two years old while sugar rationing was still in place had a 23 percent lower risk of developing dementia later in life.
Also read: The 90-minute warm bath rule, and 6 other research-backed ways to fall asleep faster
According to the BBC, dementia was also diagnosed an average of two and a half years later in this group than in people who were born after rationing had ended.
Dr. Sara Rodrigues of Alzheimer's Research UK said, according to the BBC, that maintaining a healthy, balanced diet remains one of the best ways to support brain health. She added that it is never too late to improve eating habits.