Mental disease treatment update

Mental disease diagnoses and treatments are, for the most part, primitive, messy and often only mildly effective and rather toxic. Some real mental conditions appear to not even be considered mental diseases, so people just live with it as best they can. Deep depression is one of the stinkers for which drugs can be ineffective to mildly effective, often with unpleasant side-effects. 

One area of treatment employs pulses of electrical and/or magnetic fields to increase or decrease the activity of specific regions and circuits in the brain. The pulses are used as a non-invasive way to stimulate neural pathways deep in the brain. Such treatments have been shown to be somewhat effective in treating some Parkinson’s symptoms, depression, OCD, migraines, etc. 

A new variant of this kind of non-invasive deep wave brain stimulation has recently been described in a proof of concept research paper in Nature. It is ingenious in its simplicity. The technique was used to influence a motor learning task in a small group of volunteers (n = 24). Science writer Steve Novella describes how this works: 

Researchers have now published a proof of concept study looking at what they call transcranial temporal interference stimulation (tTIS). The idea of tTIS is actually rather simple – it exploits the phenomenon of interference. Waves, regardless of what kind of waves they are, display certain core behaviors, one of which is interference. Wave are basically additive. If a peak hits a peak you get a bigger peak. If the peak of one wave coincides with the trough of another wave, the two waves will cancel each other out. This is how noise cancelling headphones work, for example.

Brain activity has a rather low frequency, and hence responds to low frequency modulation. Much higher frequencies will not coincide with brain waves and therefore have little net effect on brain activity. With tTIS, therefore, you can use two electrical stimulations that are both high frequency but off by a small amount. In the current study they used one frequency of 2000 hz and one of 2080 hz. These are both too high to directly affect brain function, so they can pass through brain tissue harmlessly. You can then aim these beams so that they intersect on the desired deep brain tissue. There the 2000 hz will essentially be subtracted from the 2080 hz, leaving an 80 hz electrical frequency. And that is a frequency which does cause neuromodulation. Voila – non-invasive deep brain stimulation. [see the simplicity here?]

tTIS is also a good example of the power of different technologies working in tandem. Here we use functional MRI scanning to see what’s happening in the brain, tTIS to modulate brain activity, and computers to model what is happening and which parts of the brain are doing what. Increasingly this computer modeling is incorporating AI to help make sense of lots of noisy data. The result is a dramatic increase in the pace of the kinds of research that can benefit from such technologies.

Think about how useful this is for neuroscience research. I wonder what that part of the brain does. Well, let’s turn it off or stimulate it and find out. The goal is to achieve not just a map of the brain or a map of all the connections in the brain, but a functional map of the brain – what are all the modules and circuits and what do they do? How does their function work as part of the whole, and what effect do they have on other circuits in the brain. This research will still take a long time, because the brain is horrifically complex, and there is a lot of neurodiversity out there. But the pace is accelerating.

This has the feel of an important new way to do deep brain stimulation. No doubt, medical researchers will try this on patients with various mental conditions. There my not be major advances in treating mental diseases, but there could be significant improvements over what exists today. Anything better would be helpful.

By Germaine: Scientist with his research assistant