Written by Kyle Proffitt
July 7, 2026 | While most research on Alzheimer’s disease (AD) in the past few decades has focused on amyloid-beta plaques and tau tangles — misfolded debris that hinders normal brain function — a group at the University of Florida has identified a new angle of endeavor by conducting an unbiased survey of all the different lipids, sugars, and small-molecule metabolites in the brains of AD patients. The notable finding was an overall increase in sugars stuck to cell surfaces in Alzheimer’s disease samples, and this work led to a surprising, and perhaps very poignant, finding that the popular joint supplement glucosamine appears to accelerate the progression of Alzheimer’s disease. The study was published in June in Normal metabolism (DOI: 10.1038/s42255-026-01538-4).
Hyperglycemia “is actually just a bunch of sugars that have been added to the outside of your cells,” explained corresponding author Ramon Sun, Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida. “When you have too much of it, the hypothesis is that your brain starts to deteriorate, your neurons no longer function properly, and you start showing signs of cognitive decline and eventually dementia.” But what is the cause and what is the effect?
New methods open new avenues of investigation
Sun’s lab is keenly interested in method development, and in this case, the methods they created enabled the new discovery. “We’re trying to take advantage of new technologies and get a fresh, new look at old chronic diseases that no one has been able to completely solve,” he said. Last May, they did Published a report Demonstrate a spatial biomolecule detection technique, applied to the brains of normal mice and model mice. A high-speed laser scans a section of tissue, evaporating the ionized molecules into a mass spectrometer, where the different types are analyzed by mass, shape and size and quantified. “We can collect metabolism, lipids and glycomics at the same time from the same piece of tissue with really high resolution,” Sun said. “Then you can reconstruct all the signals using the vital information.”
In more recent work, they improved sample preparation to enhance the detection of N-glycans (sugar chains attached to proteins), allowing the measurement of “a few hundred different sugars,” and looked specifically at post-mortem human Alzheimer’s disease and normal brain samples. “I think our study is actually one of the previous studies that was not primarily concerned with the cellular or protein aspect of Alzheimer’s disease,” Sun explained. “We just went to the metabolic side.”
They found both upregulated and dysregulated lipid species and metabolites between the AD and normal brain samples, but what really caught their attention was the striking increase in N-glycan content across gray and white matter in the AD samples. After expanding the study sample size, they observed a gradual increase in glycosylation as AD progressed, especially in gray matter.
Sun explained that these sugars in brain cells “play a normal functional and physiological role… and are actually necessary for your brain to function.” Sugar supplements help neurons recognize each other and conduct routine synaptic signals. Its importance is demonstrated in several congenital glycosylation disorders that are strongly associated with neurological defects. But what is their role in AD?
Experiences of job loss and job gain
The researchers returned to mice to study how hyperglycosylation can lead to Alzheimer’s disease. Working with two different mouse models of dementia — one amyloid-beta and one tau-driven — they identified the same patterns of increased hyperglycemia. They also noted that hyperglycemia was evident in the cortex, hippocampus, and thalamus, “regions associated with memory, cognitive processing, and neuroinflammation, consistent with known patterns of neurodegeneration in Alzheimer’s disease,” according to the paper. Isotopic labeling experiments in AD mouse models revealed increased glycan biosynthesis, in contrast to a faulty glycan degrader that accounts for elevated cell surface levels. The group also identified upregulated genes for glycan biosynthetic enzymes in both mouse AD models and human AD samples, and further detailed experiments revealed neurons as the predominant cell population experiencing increased glycan levels. “The basic structural mechanism is overactive,” Sun said.
Next, the researchers tested whether interventions could affect cell glycosylation and pathology. shRNA (short hairpin RNA)-based knockdown of PGM3, an enzyme pivotal for preparing N-glycan building blocks, reduced brain hyperglycemia and improved performance on social interaction memory tests. A drug that targets a different enzyme directly responsible for binding sugar to proteins (which had to be injected directly into the brain because it does not cross the blood-brain barrier) produced similar improvements. Interestingly, these interventions did not affect amyloid beta formation or general inflammation. Improving memory without noticeable changes in these prevalent signs of Alzheimer’s raises important questions about the true causes of the disease.
As further evidence of the functional importance, the researchers were able to exacerbate disease progression by feeding mice glucosamine daily. Glucosamine is able to cross the blood-brain barrier and feed directly into the hexosamine pathway, adding fuel for increased protein glycosylation. This intervention increased global N-glycan levels, and the mice showed memory decline. “Once you give an oral dose of glucosamine to these mouse models, it actually accelerates dementia and memory loss in these mice,” Sun said. Importantly, normal mice do not experience the same effects; Glycosylation levels and memory scores are not affected by glucosamine supplements.
Glucosamine: Consult your doctor
Glucosamine was a convenient agent to directly supply the hexosamine pathway to attach N-glycan to proteins, but of course it is a well-known supplement for joint pain. It was perfectly reasonable for researchers to wonder whether glucosamine supplements might affect or accelerate Alzheimer’s disease. They accessed records from the University of Florida Health System covering more than 50,000 patients with Alzheimer’s disease-related dementia (ADRD), a group that includes Alzheimer’s disease but also vascular dementia, Lewy body dementia, and frontotemporal dementia. The researchers compared the data of these patients with those with mild cognitive impairment (MCI) and found that in both groups, about 8% used glucosamine regularly. By analyzing 10-year survival, they identified an approximately 25% increase in mortality for glucosamine users in the ADRD group, while mortality was not significantly affected in the MCI group. However, as a general rule, about 5% of patients with mild cognitive impairment (MCI) annually convert to ADRD. Interestingly, for glucosamine users in the MCI group, there was a 25% increased probability of transitioning to ADRD at the 10-year follow-up; The total number of individuals transitioning from MCI to ADRD in this time period increased from about 48% to about 60% when taking glucosamine.
Sun’s theory here is that the early stage of Alzheimer’s is difficult to diagnose, and in patients who have been diagnosed with MCI but already have Alzheimer’s, “for those who take glucosamine, it gets much worse” and the disease becomes more apparent more quickly. The main conclusion from these results is that there is an Alzheimer’s disease-specific vulnerability to glycan overload. “The good news is that glucosamine doesn’t really affect anything if you don’t already have the disease; it’s a disease-specific factor,” Sun said.
Sun’s recommendation, for now, is a bit cautious: A future trial is warranted, but until one is done, he would “use caution for people with Alzheimer’s who are also taking glucosamine; I would say talk to your neurologist or primary care doctor to evaluate whether you really need it.” If glucosamine were a truly effective treatment, it would be difficult to give this advice, however Analytics He owns constantly to fail To determine whether glucosamine/chondroitin sulfate supplements are more effective than placebo. The impact of this advice can be enormous. Based on the number of individuals with Alzheimer’s disease in the United States and the 8% likely to use glucosamine, this could mean that “more than 1 million patients may inadvertently worsen the progression of their disease through glucosamine supplementation,” according to the paper.
Pending questions
Several questions remain. The team has not determined why the glycosylation machinery is overactive in the brains of Alzheimer’s patients in the first place, nor how excess surface sugar translates into neurological dysfunction. There’s at least a theory about the effects: “If you have a lot of sugar on the outside of your cell, you can totally imagine that it will start to aggregate and disrupt all cellular processes,” Sun said.
They also did not directly test the relationship between dietary or circulating glucose and glycosylation in the brain, although the same biosynthetic pathway could be fueled by glucose as well as glucosamine – a plausible biochemical bridge to the long-observed epidemiological link between diabetes and Alzheimer’s disease risk. There is an interesting wrinkle to this idea though. Other studies have shown that glucose uptake in the brains of people with Alzheimer’s disease does not increase, but rather decreases, even years before clinical symptoms appear. Because these processes occur in brain cells with low glucose levels, there is a suggestion that increased glycosylation and upregulated glycan synthetic enzymes are compensatory mechanisms.
the Complete metabolomics dataset The basic paper has been issued; “All of this data is publicly available,” Sun noted. “People can download the data and start playing with it for themselves… There are a lot of different pathways that are dysregulated in Alzheimer’s disease, and we chose just one to validate our findings.”
What happens next
A prospective trial of glucosamine in Alzheimer’s patients is the obvious next step. Even then, human data remain correlative, and mouse data carry causal weight, a limitation that Sun acknowledged while claiming that the convergence between human screening, the mouse mechanism, and the results of clinical records is sufficient to warrant clinical caution and real-world experimentation.
In terms of treatment, the most immediately actionable step is to stop adding glucosamine to a brain that is already hyperglycemic. The harder and longer route is a drug that penetrates the brain to stifle the glycosylation pathway, but the blood-brain barrier “is usually the biggest challenge to finding drugs that reach the brain,” Sun said. Gene therapy and siRNA approaches are also on the table. The laboratory itself does not seek to discover drugs. “We are currently working on something different that can also modify brain metabolism,” he said. This includes lifestyle changes – diet, exercise, sleep apnea, oxygenation – and how these factors shape the course of the disease. There is a dividing line where Sun is interested in why some individuals with a disease deteriorate rapidly while others do much better. As the glucosamine story shows, “anything you do on a daily basis affects—either inversely or accelerating—how quickly or slowly your disease progresses.”
