A close family member was recently diagnosed with Alzheimer’s disease. For years, she’s had unusually strong changes in mood associated with her diet – we’d always joke that if she was out and about, we always needed to make time for her afternoon chocolate cake fix or she’d get cranky. But what if these sugar-associated mood swings were an early indication that she was at risk for Alzheimer’s?
In medical school, we learn that there are only really two sources of energy for the brain – one is glucose (which is well-known to damage other parts of the body). The other is ketone bodies, something that is made by the liver specifically to cross the blood-brain barrier and feed the brain in times where blood glucose has dipped too low.
Given that glucose can wreak such havoc on the body, our brains depend on glucose for fuel more than our bodies do, and insulin receptors in the brain control neuron function, it seems logical to link poor diet and damage to the brain. And it turns out that there is a evidence building around this hypothesis. This opinion piece from the New York Times provides a summary of research indicating that Alzheimer’s is caused by diet. This disease has significant social and economic implications, since one in eight older Americans has Alzheimer’s, and this diseases is associated with over $200 billion in spending on care and medication. And this is a worldwide problem that will only get worse in time – Alzheimer’s Disease International estimates that the prevalence of Alzheimer’s will double every twenty years, from 36 million people worldwide in 2010 to a predicted 115 million in 2050.
A significant focus of Alzheimer’s research has focused on genetic determinants of the disease, yet genetics seem to be responsible for only 1-2% of cases – in the rest of patients, the cause of the disease is unknown. These findings from Brown University indicate that there is need for additional research around prevention. Initial questions may include the following –
- What is the biochemical pathway that leads to plaque formation?
- Is it caused by insulin or glucose or the body’s slow response to low blood glucose in forming ketone bodies?
- Are there early warning signs that the brain might be developing Alzheimer’s, like changes in blood glucose or insulin levels do for diabetes?
- In type 1 and 2 diabetes, high blood glucose levels indicate that the insulin is not working well, either because its receptors are damaged or it is not being produced. But while diabetes is a significant risk factor for Alzheimer’s, the two diseases do not always occur in the same patient populations. Why would this be the case?
Need for significant additional research around long-term chronic diseases is one of the reasons that I find this new movement towards improved health IT to be so exciting. this movement has the potential to link real-time data on patient biochemistry with long-term health outcomes to provide information about the causes and correlates of disease. Companies like glooko and Scanadu will soon be generating a rich dataset of constant data on blood pressure and blood glucose levels that can be linked to information about the onset of chronic and preventable diseases.
Maybe these 4pm chocolate cravings were prompted by an easily-anticipated dip in blood sugar (and a corresponding dip in insulin) that caused the brain to go without fuel. Maybe this was a sign of a larger issue of metabolism or an inability to generate enough glucose during lean times that science just didn’t have the tools to recognize yet. Could we have changed something in her diet to prevent plaques from developing? In the future, innovations in data collection improves the chance that we can answer these questions. Furthermore, data about direct biochemical outcomes from lifestyle choices might serve as a great tool for promoting prevention. I often can’t resist that 4pm cookie. But if I had hard data that it was slowly causing my brain to lose function, I’d sure as hell pick another guilty pleasure.
Regardless, there is a huge potential for learning here – it will be a great day if we can collect concrete data that points to methods of reversing the rise of Alzheimer’s worldwide.