A groundbreaking new study suggests that Parkinson's disease could be detected nearly nine years before an official diagnosis through a simple movement test that tracks changes in how quickly a person turns while walking. Parkinson's is a devastating neurodegenerative disorder characterized by progressive damage to parts of the brain over time, with the disease often taking hold years before overt symptoms appear, eventually leading to tremors and severe movement problems.

While scientists have long recognized the critical importance of detecting individuals in the earliest stages of the disease, known as the prodromal phase, developing an effective pre-symptom test has proven challenging. However, German neurologists have now made a significant breakthrough, discovering that difficulties in turning during walking could help identify Parkinson's 8.8 years prior to diagnosis. Publishing their findings in the journal Annals of Neurology, the researchers emphasized that 'Turning is a complex part of walking. It requires constant coordination, and modification of the locomotor trajectory while moving.' They added that 'Difficulties turning are common and highly relevant to daily life in Parkinson's,' making turning deficits a crucial area for investigation in the pre-diagnostic phase.

The research specifically found that turning more slowly and at a wider angle whilst walking was consistently associated with an increased risk of Parkinson's. For their study, researchers analyzed the movement patterns of 924 participants over the age of 50, all free from significant hearing or visual impairments, from the Tübingen Evaluation of Risk Factors for Early Detection of Neurodegeneration (TREND) study. Over a 10-year period, participants completed a test five times, which involved walking a 20-meter long hallway for one minute at their preferred pace, equipped with a wearable tracker on their lower back.

The results indicated that slower turning at baseline was linked to a higher risk of Parkinson's diagnosis, with noticeable deviations from control groups emerging almost nine years before an official diagnosis. By the study's conclusion, 23 participants had been diagnosed with the disease, approximately five years after their initial baseline tests. Utilizing machine learning, which accounted for factors such as age, sex, and the participants' top turning speed, the researchers successfully identified 60 percent of patients in the early stages of Parkinson's.

Participants generally exhibited slower turning as they aged, but those who went on to receive a Parkinson's diagnosis began to turn more slowly and at a wider angle up to 8.8 years before their official diagnosis. Experts suggest this might signify a deterioration in overall movement speed or in balance and postural stability, both commonly affected by Parkinson's. The researchers hypothesized that 'A decline in postural stability may subconsciously incentivise patients to turn slower and adopts a safer route, using a larger arc,' implying that pre-diagnostic Parkinson's patients develop compensatory strategies for safer, more stable turning.

Interestingly, the study also revealed specific demographic risk factors: men were found to be at an increased risk, being four times more likely to develop the disease than women. Furthermore, every one-year increase in age was associated with a 15 percent increased risk of Parkinson's. The researchers concluded that 'Our results suggest that turning measures may aid in predicting the clinical Parkinson's diagnosis and enhance a panel of prediagnostic markers for identifying high-risk individuals.' They also noted the practicality of their approach for large-scale screening, as it uses 'a single wearable inertial measurement unit and validated algorithms.'

While this marks the first prospective longitudinal study to evaluate turning measures in Parkinson's, the researchers acknowledged certain limitations, such as the inclusion of only seven turning measures. They suggested that 'Future work can investigate more turning characteristics, also in combination with gait and balance characteristics' and that a larger sample size would yield more generalizable results.

Currently, there is no definitive test for Parkinson's, with diagnosis typically relying on the development of later-stage symptoms like tremors, after other potential health conditions have been ruled out. Parkinson's charities estimate that over one in four patients are misdiagnosed before receiving the correct diagnosis. The condition is thought to affect approximately 153,000 people in the UK and 500,000 Americans, with a recent study suggesting over 20,000 people in Britain might unknowingly be living with it. In the UK, two people are diagnosed every hour, and the disease costs the NHS over £725 million annually.

Early signs of Parkinson's include tremors, stiffness, slowness of movement, and loss of smell. Balance problems, issues with coordination, and muscle cramps are also common indicators. Patients frequently experience mental health challenges such as depression and anxiety as a consequence of the disease. Parkinson's is caused by the death of dopamine-producing nerve cells in the brain, a chemical crucial for movement. Experts continue to investigate the triggers for this nerve cell death, with current thinking pointing to a combination of genetic changes and environmental factors. The risk of developing the condition generally increases with age, with most patients diagnosed after 50.