A study by Iowa University neuroscientist John Wemmie, M.D., Ph.D. and published in the Proceedings of the National Academy of Sciences (PNAS) Early Edition reveals that elevated acidity or low pH-levels are associated with panic disorders, anxiety and depression and that changes in the brain’s acidity are significant for normal brain activity.
Wemmie, a UI associate professor of psychiatry says:
“We are interested in the idea that pH might be changing in the functional brain because we’ve been hot on the trail of receptors that are activated by low pH. The presence of these receptors implies the possibility that low pH might be playing a signaling role in normal brain function.”
According to his study findings, the brain requires acid-sensing proteins to produce normal fear responses, as well as for learning and memory in mice. He states that although it is easy to obtain a kit to measure the pH-level (acidity) for garden soil for instance, there are currently no simple tests that can measure pH changes in the brain.
In collaboration with Vincent Magnotta, Ph.D., UI associate professor of radiology, psychiatry, and biomedical engineering, the team developed and assessed a novel, non-invasive approach to identify and monitor pH-changes in living brains.
Their novel MRI-based imaging technique currently provides the best evidence that pH changes do indeed occur with normal intact human brain function, in particular in detecting global changes in the brain pH-level in mice. They discovered that the signal increased during the inhalation of carbon dioxide, lowering the brain’s ph-level, making it more acidic, whilst bicarbonate injections decreased the MRI signal, increasing the brain’s pH-level. The relationship between the signal and the pH was linear over the tested range.
Significantly, the test also appears to detect localized brain activity. The team conducted a classic experiment that activates the particular region in the brain associated with vision, by asking human participants to view a flashing checkerboard. They observed, that the MRI method identified a drop in pH-level in that particular region.
Magnotta, an expert in developing MRI (magnetic resonance imaging)-based brain imaging techniques says: “Our study tells us, first, we have a technique that we believe can measure pH changes in the brain, and second, this MRI-based technique suggests that pH changes do occur with brain function.”
Wemmie adds: “The results support our original idea that brain activity can change local pH in human brains during normal activity, meaning that pH change in conjunction with the pH-sensitive receptors could be part of a signaling system that affects brain activity and cognitive function.”
The new technique may also offer a new alternative of brain I’maging. The functional MRI (fMRI) currently measures the brain’s activity by detecting a signal caused by oxygen levels in the blood flowing to active brain regions, whereby the new method responds to changes in pH-levels without being influenced by changes in blood oxygenation, yet fMRI is unable to respond to changes in pH-levels.
Wemmie states: “What we show is our method of detecting brain activity probably depends on pH changes and, more than that, it is distinct from the signal that fMRI measures. This gives us another tool to study brain activity.”
His earlier studies indicated that pH-changes were likely to play a role in certain psychiatric diseases, such as anxiety and depression. The new technique may enable Wemmie and his team to investigate further into what impact pH-changes play in these conditions.
He concludes saying:
“Brain activity is likely different in people with brain disorders, such as bipolar or depression and that might be reflected in this measure. And perhaps most important, at the end of the day; could this signal be abnormal or perturbed in human psychiatric disease? And if so, it might be a target for manipulation and treatment?”
Written By Christine Kearney