In a bid to revolutionize Alzheimer’s detection, scientists have examined the brain’s neurovascular unit. The research revealed not only how this system is altered by the disease, but also found distinctive breathing patterns in affected individuals.
Testing for Alzheimer's disease was once possible only in post-mortem examinations but thanks to years of research, detecting the condition in living patients is becoming more and more possible. While we've seen approaches that look for the disease using eye scans, earbuds, and even a smartphone speech app, the current standard for finding the condition is to look for the markers of amyloid proteins in cerebrospinal fluid (CSF), or to use a positron emission tomography (PET) scan. But obtaining CSF is an invasive procedure and PET scans can be quite costly.
Plus, while there's no doubt that the development of plaques caused by amyloid proteins is a hallmark of Alzheimer's, thanks to the failure of several drugs that treat them, it's becoming clear that they are likely not the cause of the disease.
Wondering if there were other identifying markers scientists could use to identify and potentially treat Alzheimer's disease, a research team from the University of Lancaster (UL) in the UK and the University of Ljubljana Medical Centre in Slovenia turned to examining the brain's neurovascular unit (NVU), a network of brain cells connected to blood vessels. The team theorized that Alzheimer's disease might be characterized as a result of the brain not getting enough nourishment from the blood vessels.
“With disappointing results from protein-focused drug trials, the vasculature and neurovascular unit are promising targets for future treatments of Alzheimer’s disease” said study co-author Bernard Meglič.
Out of sync
To analyze the NVU and see how Alzheimer's might affect it, the team applied a trio of monitoring devices to a group of patients diagnosed with the condition, and to a control group unaffected by it. They used electrical and optical probes applied to the scalp to monitor the brain's electrical activity and oxygenation, an electrocardiogram (ECG) to measure heart rate, and a strap around the torso to measure breathing.
This triple approach allowed them to see how all of the systems were working in concert, and observe how cycles of oxygenation and blood flow (oscillations) were disrupted in Alzheimer's patients. They found that in non-affected patients, the oscillations occur in the 0.1 Hz frequency, a cycle of activity that happens about once every 10 seconds. In Alzheimer's patients, however, these oscillations were disrupted and out of phase.
In other words, in patients with Alzheimer's, the rising and falling of blood oxygen levels was fairly out of sync with the pulsing of the blood vessels that are supposed to deliver that blood to the brain. The finding backed up the theory that oxygenation of the brain might be implicated in the disease.
Interestingly, the team also discovered a disruption to breathing patterns in Alzheimer's patients. Those without the condition took approximately 13 breaths per minute, while those with the disease took about 17 breaths per minute.
“Quite unexpectedly, we also detected that the respiratory frequency at rest is significantly higher in subjects with Alzheimer's disease," said UL's Aneta Stefanovska, the study's lead author. "This is an interesting discovery – in my opinion a revolutionary one – that may open a whole new world in the study of Alzheimer's disease. It most likely reflects an inflammation, maybe in the brain, that once detected can probably be treated and severe states of Alzheimer's might be prevented in the future.”
Stefanovska says that she and her team are considering launching a spin-off company to further develop the technique, as they believe it can be a brand-new way to detect Alzheimer's affordably, non-invasively, and relatively simply.
The study has been published in the journal, Brain Communications.
Source: Lancaster University