The Promise of Transcranial Stimulation
Along with its pioneering work in neurofeedback for the treatment of eating disorders and co-occurring conditions, Mirasol has been offering trans-cranial electrical stimulation to clients in its PHP partial hospitalization program.
Trans-cranial electrical stimulation applies very low levels of electric current to areas of the brain associated with depression, anxiety, OCD and ADHD. These low levels of current can affect the plasticity of the brain, allowing more functional brain behaviors to be learned quicker and easier, supporting therapy for these conditions.
Dr. Sanjay Manchanda coordinates the program, and he recently conducted training for Mirasol staff on how it works and its potential health effects, including an update on current research.
How It Works
The basic idea is very simple. You place a positive electrode and a negative electrode on the brain, and the current flows from positive to negative [conventional current]. So why would this small amount of current affect our behavior, activity, thinking and mood? The brain has cells in it called "neurons" with terminals that connect to other neurons. Think of it as a chemical-electrical organ, with these neurons acting as circuits. The membrane of the neuron is charged — positively on the outside and negatively on the inside. At some point the positive outside charge increases until it short-circuits across the membrane, and we say the neuron "fires" and provides information to the next neuron. When you place a battery terminal across the brain, depending on how it's oriented, it affects this charge. So what DC current does is affect the resting membrane potential of neurons. You can either increase the potential or decrease the potential.
So it turns out that that has a strong effect, because when the neurons fire together, the brain is plastic. It actually improves the efficiency of firing. This is a general principle in brain training. We have noticed that whenever you repeat a particular type of thinking or task, the brain gets better at it. That's because the hard wiring in the brain changes the ways the synapses operate to make them more efficient; the firing happens more quickly and easily. That's called "synaptic plasticity".
For a long time the conventional wisdom was that the brain wiring did not change. Only in the last few decades did we realize that the brain actually physically changes as you learn new things. A basic psychological and yogic principle is that when you repeat some kind of behavior or thinking, it creates something like a "groove" in the consciousness. So what the DC stimulation is doing is affecting the ability of that groove to form or not form.
One way of using DC stimulation is to improve learning. How that works is you identify the area of the brain associated with expert task recall. What parts of the brain become more active when you become really good at that task? And then we apply current to that part of the brain in such a way that we help the brain to wire itself more quickly. We find the task-significant area of the brain and we stimulate it while you are doing the task.
This has been tested in several ways. A study was done for the Air Force, which is trying to teach drone pilots to detect targets quickly. They took functional MRIs of the brains of people who were novices and experts at that task. What a functional MRI does is tell you how much glucose is being used in a particular region of the brain while you are doing — or not doing — that task. The Air Force found that by stimulating those regions while training someone to detect threats, they could reduce their training time by 50%.
There's an article by Sally Adee, an editor at New Scientist, who went to a lab in San Diego and learned how to fire a rifle. They hooked her up to an electrode on her right temple and turned on the current, and suddenly her mind was quieter, and she could focus, and she did much better. Many people do report that this protocol can quiet the mind. Part of the purpose of the right frontal lobe is to predict negative future consequences. So when it's overactive, as it is in a lot of us, it can do too much of that.
Transcranial Stimulation and Depression
There are a lot of studies on direct current stimulation and depression. Typically you place a positive electrode on the left pre-frontal lobe, and a negative electrode on the right. People who have generally have a more positive, enthusiastic attitude have more activity in the left frontal lobe of their brain. And people who tend to be depressive have the opposite. Can tDCS be used to increase activity in the left frontal lobe and decrease activity on the right side? The answer is "yes". We have studies that show that tDCS can be used to improve mood, reduce pain, help with stroke recovery, improve motor function as well as accelerate learning and improve memory and attention.
Safety and Ease of Use
Among the advantages of tDCS are its ease of use and relative safety. The devices are inexpensive and small in size, and you can use them at home and even do other things while using it. The current used is at a very low level, so brain tissue is not endangered.
You can cause some skin tingling, burning and itching if you're not careful. You can definitely have adverse effects, because you have effects. Any treatment that has effects will have adverse effects if those effects are not what you want. But the effects are not long-lasting for one treatment. It's only if you keep repeating that treatment over time that you could begin to have problems.
TDCS is getting more popular for consumer use. There are a lot of websites. There's Do-it-yourself tDCS.com has a lot of information. There's a huge Reddit group. And there's a company called Foc.us that is promoting consumer-level units with electrodes in a baseball cap that they recommend you try while doing sports.
However, there are questions about the consumer products, because this is a fairly strong treatment. The FDA is taking a look at whether these devices should be regulated in some way. For example, if you do positive stimulation of the left pre-frontal cortex, it reduces your perception of pain while training. This may or not be a good thing, because your pain has a purpose.
Individualized treatment can be used to minimize side effects. One of the things we do as neurofeedback clinicians is to conduct a 19-channel EEG recording of the brain, and we analyze it according to the spans — alpha, beta, gamma and delta. Our brains have different frequencies, and each frequency is like a note. So the brain is like a symphony, playing all these different notes. Once we get a recording, we can analyze it and produce a map, and compare the activity in different parts of the brain to the average. Then we choose the placements of the electrode based on the map.
Certain patterns are associated with OCD or ADHD. When the left central cortex has low activity, that's one of the correlations with ADD. What happens in ADD and ADHD is that certain parts of the brain are going too slow. That's why when you give the person Ritalin or some other type of amphetamine, the person feels better. So what we would do there is place the positive electrode on the left C3 site, and the negative on the right shoulder.
Transcranial Alternating Current Stimulation (tACS)
Let's talk a little about alternating current stimulation. In alternating current, you are using AC current instead of DC current. The current is very low and is applied to various locations on the scalp, such as the mastoids behind the ear. There is only one current, and it travels in both directions. You can have different waveforms when you use DC current. The frequency can also change. So one thing that happens in AC stimulation is that we quickly get confused by the possibilities.
The research is still quite limited. Early research in Russia by Limoge and Lebedev included something they called "electroanesthesia". They developed a form of AC stimulation that would stimulate the brain in such a way that you wouldn't need anesthesia. They used a frequency of 77.5 Hz plus a DC current simultaneously, and they showed that this frequency caused the maximum release of positive neurotransmitters. There's a device on the market called "Nexalin" that uses this principle and that has shown good results in treating anxiety and depression. Some consumer devices also now available and have been shown to be useful for reducing anxiety, depression, insomnia and pain.
I've been working with Dr. Robert Crago and Dr. Andrea Russell here in Tucson on different ways to use AC stimulation, and we just started a research project on a tune-up protocol. We use electrodes on the mastoids, behind the ear. The basic plan is to start at very low frequencies and stimulate up the band to very high frequencies. And the reason this works is because you are teaching your system to get comfortable at different levels of arousal. One of the things we discovered is that the low frequency training has to be two to five times longer than the high frequency training. And why is that? Because we're creating a base of rest for the person.
Our rationale is that if we stimulate across a range of frequencies, it will help increase the depth, breadth and flexibility of access to mind states, and also create a base of rest and relaxation for higher more excited cognitive functioning to ride on. The way I think about it now is that each frequency is like an index, and if you stimulate across a wide range, it increases your ability to be in different states. Should you always be in a mid-range, neutral state? No, it just depends on what's needed. When you want to go to sleep, you need to really ramp down. When you have a demanding task, you need to ramp up. Most of our problems with self-regulation are when we get stuck in certain states.
Transcranial Stimulation and Mindfulness
What we want to achieve is a high mindfulness state. For this I'm going to invoke a list of seven factors of enlightenment that Buddha came up with in his teachings thousands of years ago. And he said that people who really want to achieve more freedom from suffering and knowledge of self are more likely to succeed if they develop these seven factors:
- Relaxation or tranquility
- Joy or rapture
So you can think of mindfulness as a balance between calming factors and activity. If you balance these factors, you achieve mindfulness. That's what the tune-up is helping us to do.