Essential Tremor Brain Signals: Like Off-Balance Pairs Skaters

Many fans of the winter Olympics most enjoy the pairs figure skating events. A man and woman perform dance-like routines. Their moves express the music’s mood, whether dramatically energizing or poetically serene. When their athletic talents are synchronized flawlessly with each other and their choreography, the effect is breathtaking. To see what I mean, take a few minutes to enjoy the gold medal winners from the 2018 Olympics, Savchenko and Massot.

Maintaining balanced harmony

When harmony exists, the skaters’ routine moves smoothly and correctly. Each member of the pair trusts the other’s practiced technical skills to contribute to a seamless and expressive performance. We may not perceive how much give and take is occurring, but they are completely reciprocal. Thus, if either makes a mistake, both of them are thrown off balance. These examples reveal how quickly the bubble of harmony bursts—though it’s practically impossible to identify the precise nanosecond that sets off a chain reaction culminating in an all-too-obvious collapse.

Essential tremor: is something out of balance?

For our bodies to move as we need them to, the signals that originate in the brain’s neurons (nerve cells) depend on correct transfer from one neuron to the next (or sometimes to several neurons at the same time). The trail of neurons is a kind of pathway composed of “senders” and “receptors.” A signal is sent either biochemically (neurotransmitter) or electrically; the receptor has to receive and interpret it correctly, making each neuronal transmission a reciprocal process. Just as with a pair of figure skaters, when the transmissions are in synch, the resulting movement is a seamless and expressive performance.

However, it only takes a nanosecond for something to start the chain reaction of abnormal transmissions that result in all-too-obvious essential tremor (ET). While we think that the dysfunctional signal originates in the part of the brain called the cerebellum, we don’t yet know exactly what causes it. However, we do know that once it begins, it travels along what is called the tremor pathway.

One theory of essential tremor (ET) is that it has to do with an imbalance. As the signal moves from one neuron to another, the receptor must “decide” to what degree it should rev it up (excitatory response) and/or calm it down (inhibitory response). In normal situations, the neurons maintain a proper balance between excitatory and inhibitory responses. However, in the case of ET, the theory is that somewhere early along the line in the cerebellum, the balance between excitatory and inhibitory responses is thrown off, setting up an abnormal chain reaction leading to tremors. While we aren’t sure if the imbalance theory is correct, or even if it’s universal for all cases of ET, here is simple evidence:

  • Stimulants such as caffeine lead to a biochemical excitatory response, so tremors can worsen.
  • Depressants such as alcohol lead to an inhibitory response, so tremors can calm down.

This raises an interesting question: Could we regulate tremors by getting the responses back in balance?

Can we restore the balance?

If the imbalance theory is on target, restoring the balance would require toning down the excitatory response and/or ramping up the inhibitory response. An interesting study done with lab rats found that a natural compound from certain plants appeared to have the desired effect.

The compound is called berberine. It’s found in several different plants including goldenseal, tree turmeric and barberry. It has a strong yellow color and has been long used in folk medicine. In fact, its potential medicinal properties have been tested for treating heart arrhythmia, high cholesterol, diabetes, inflammation, Parkinson’s disease and Alzheimer’s disease.

Since rats in nature don’t get ET, it has to be chemically induced by injecting the rats with a chemical that causes tremor signals in the brain, with the result of limb and postural tremors. In this study, groups of tremor-induced rats were given different doses of berberine before being injected. The researchers found that at a low-to-moderate berberine dose, tremors and gait disturbances were reduced; however, at a high dose, there was either no effect or there was a negative effect on certain movements. The research team believes that berberine’s properties block certain excitatory receptors (or the neurotransmitters that activate them), with the effect of calming down the excitatory response.i If so, then berberine appeared to help restore the balance between the two responses.

NOTE: Berberine is commercially available as a supplement but is NOT proven to control ET. It can have toxic effects or interfere with certain medications. Sperling Neurology Associates strongly advises against experimenting with berberine. ALWAYS consult a doctor about taking any new product or supplement.

A reason to hope

The scientific world is constantly exploring clues like berberine to create new ET treatments. Until we know ET’s root cause and find a way to prevent it, today’s therapies are aimed at controlling tremors. A great source of hope for those with ET is MRI-guided Focused Ultrasound (MRgFUS) which stops tremors by interrupting the pathway. MRgFUS destroys a very small signal “relay station” in the thalamus of the brain. Whether or not the signal is the result of a neuron response imbalance, MRgFUS cuts it off before it can go further on the pathway, without causing harm to other brain functions. The affected hand can once again move normally, like the figure skaters who corrected their imbalance and went on to achieve a beautiful and complete routine.

i Vaziri Z, Abbassian H, Sheibani V, Haghani M et al. The therapeutic potential of Berberine chloride hydrate against harmaline-induced motor impairments in a rat model of tremor. Neurosci Lett. 2015 Mar 17;590:84-90.

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