In 2017, David Nichols, a 29-year-old mechanical engineer from the USA, fell while rock climbing on the Enchantments Mountain range in Washington, suffering a brain injury.
After the incident, he experienced difficulty with coordinated movements such as balance, posture, walking, and sitting, along with tremors in his legs and right arm. Moreover, he could barely talk.
Speaking to Happiest Health from his Portland, Oregon home, Nichols explained that he was diagnosed with a rare movement disorder named spinocerebellar ataxia type 6 (SCA-6) soon after. According to a 2021 study, SCA-6 is a rare condition that progresses with age, affecting 2.7 in 1,00,000 people.
“SCA-6 happens when there is damage in the cerebellum [brain region that controls the muscle movement in the body]. Hence, it is not associated with neurological symptoms [like dementia or cognitive impairment],” says Dr Syed Moed Zafer, consultant neurologist and movement disorder specialist based in Bengaluru.
SCA-6 is characterized by gait unsteadiness, stumbling, imbalance in coordination in both upper limbs, tremors, and speech difficulties, adds Dr Zafer.
The many avatars of SCA
Spinocerebellar ataxia is a hereditary neurological condition characterized by degeneration of the cerebellum, spinal cord and other nerve connections in the brain.
So far, studies have identified 40 types of SCA that are classified based on the mutation and location of the mutation on the DNA.
“It is a rare genetic autosomal dominant degenerative condition, and SCA-6 is one of the subtypes of SCA”, says Dr Zafer. It means either or both parents can pass the faulty gene to their offspring.
Read more: Know your brain regions
The gene link
Studies have shown a mutation in the CACNA1A gene causes damage to the primary cells in the cerebellum region called Purkinje cells. This damage leads to SCA-6, the condition triggered in Nichols by a traumatic brain injury.
Purkinje cells receive information from other parts of the nervous system and integrate them to coordinate movements and behaviours.
In a healthy individual, the CACNA1A gene produces glutamate, a neurotransmitter that facilitates certain brain and movement functions. However, in SCA-6 condition, a mutation in this gene produces poly Q, a toxin that impairs the delivery of glutamate to Purkinje cells. Poly Q forms clumps in the Purkinje cells hampering their activity in the cerebellum.
In a recent study published in Science Advances, researchers from McGill University, Canada, experimented with ways to revive the activity of Purkinje cells. They used a combination strategy: specific medicine and exercise to achieve the results.
“When Purkinje cells don’t work properly or eventually die, such as in SCA-6, affected individuals often have problems with motor coordination,” says Dr Alana Watt, study author and associate professor at McGill University, Canada.
Read more: Unlocking the mysteries of ataxia
Looking into the future, in hope
According to this study, SCA-6 reduces the activity of brain-derived neurotrophic factor (BDNF) in the brain. BDNF is essential for strengthening neurons, neurotransmitters, and neuron plasticity during adult brain development.
Prof Watt’s team hypothesised that increasing the activity of the BDNF molecule could slow disease progression. A combination of medication and exercise was found to be effective in the early stages of SCA-6.
The researchers tested three groups of mice with the SCA-6 condition: one was given a specific drug (7,8-DHF); one was on an exercise regimen for one month; and one given both.
They observed that:
- The mice treated with only the medicine saw an improvement in BDNF activity, but it did not affect the healthy cerebellum cells.
- Exercise-only treatment in the second group improved the BDNF activity marginally, while also activating healthy cells.
- The third group, treated with both medicine and exercise, showed remarkable results with increased BDNF activity and healthy cerebellum cell activity.
Prof Watt concludes that early diagnosis and intervention are crucial for the combination treatment to be effective, as it was ineffective when the motor coordination problem had advanced before treatment began.
“We only tested the drug in an animal model, so we don’t know whether this will work the same way in people with SCA-6. But, of course, we always hope that our work will translate to humans, but careful clinical trials will be needed to check that the drug is effective and safe,” says Prof Watt.
While there is no cure yet, symptoms like tremors, seizures, depression, and eye discomfort can be managed by rehabilitation, says Dr Zafer. “Some medication will control the symptoms, but it does not halt the progression of the disease,” he adds.
Studies have shown that physiotherapy, occupational therapy, and exercise help regain motor function in affected individuals.
Nichols says he has been engaging in exercise and physiotherapy for over five years. “I can see improvement in my condition as I can walk slowly and independently now. My speech has also improved,” he says.
Read more: More than just clumsiness: understanding developmental coordination disorder