Parkinson's disease, a condition that affects the brain and causes uncontrollable movements such as shaking, tremors, and stiffness, is the fastest growing neurological condition globally.
It is caused by a loss of nerve cells in part of the brain, and currently, there is no cure. According to Parkinson's UK, an estimated 153,000 people are living with a Parkinson's diagnosis in the UK as of 2023.
While tremors and slow movement are the main symptoms of Parkinson's disease, studies have shown a symptom that could present long before a person is diagnosed.
Researchers have previously reported a link between a Parkinson's disease gene and vocal issues, leading to a soft monotonous voice.
These vocal symptoms often appear much earlier - sometimes decades - before movement-related issues, according to a study conducted on songbirds by neuroscientists in the lab of Julie E Miller, assistant professor at the University of Arizona.
Studying the zebra finch, whose brain that deals with speech and language is also organised very similarly to humans, scientists found the gene did affect song production.
The birds with the gene sang less after two months, and they sang less at the start of a song session three months after receiving the gene. Their vocalisations were also softer and shorter - findings similar to what is seen in Parkinson's disease.
Recent advancements in Parkinson's research have led to the development of an automated screening method that can distinguish between the voices of Parkinson's patients and those of healthy individuals.
Scientists at Providence Saint John's Health Center in Santa Monica, California, discovered their model could accurately predict 80 to 90 per cent of cases among those with Parkinson's Disease.
The American Parkinson Disease Association (APDA) highlights four primary motor symptoms of the condition, including bradykinesia, which is slow movement. Bradykinesia can impact a person's voice, potentially causing it to become softer or start strong before fading away.
There may also be a loss of normal variation in volume and emotion, leading to a monotone sound. In advanced stages, speech may become rapid and crowded, or stuttering may occur.
Additionally, bradykinesia can result in a "mask-like" facial expression, making it difficult to interpret emotions. Speech problems vary among individuals with Parkinson's, with some experiencing frustration in finding the right words.
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