Understanding the Ascent of Subjective Vertical Position on Parkinson’s Disease Patients’ Posture

A groundbreaking study published in the esteemed journal, Parkinson’s Dis, has cast light on the predictive value of the subjective vertical (SV) position in assessing the progression of postural impairment, specifically forward flexion of the trunk (FFT), in individuals living with Parkinson’s disease (PD). The potential impact of these findings could be far-reaching, considering the prevalence and the incapacitating nature of PD, which affects more than 10 million people worldwide.

The Study at A Glance

The research, conducted by Mikami et al. from various medical institutions in Japan, including the Department of Rehabilitation, Noborito Neurology Clinic, and the Department of Neurology, St. Marianna University School of Medicine, presents intriguing evidence that an anterior shift in the subjective vertical position correlates with a worsening of forward trunk flexion. The longitudinal study’s completeness over a year provided substantial insights into disease progression and possible predictive markers for therapeutic interventions.

The cohort comprised 39 patients with Parkinson’s disease. Parametric evaluations, conducted at baseline and one year later, measured several clinical aspects such as the Unified Parkinson’s Disease Rating Scale scores, Mini-Mental State Examination (MMSE) scores, modified Hoehn & Yahr (mH&Y) scores, SV angle, FFT angle, and levodopa-equivalent dose (LED).

Despite the statistical attrition, with only 46% of patients completing the study, the results were statistically significant. Increases in SV angle correlated with a similarly marked increase in FFT angle, demonstrating a potential link between perceived posture and actual physical manifestation.

The Meaning Behind the Metrics

Before delving into the intricacies of the study, it is critical to understand what is meant by FFT and SV within the context of Parkinson’s disease. FFT, a motor symptom of PD, is characterized by an involuntary forward bending of the trunk, which impacts balance and mobility. The SV angle is a subjective measure indicating how patients perceive their upright posture.

In the study, researchers meticulously analyzed the difference in SV and FFT angles from baseline to the follow-up period. It was revealed that patients with an increased SV angle – indicating a loss of accurate vertical alignment perception – were more likely to exhibit a significant increase in FFT angle. Their bodies seemed to adjust according to the perceived, inaccurate vertical position, worsening their postural deformities.

The Importance and Potential Applications

The significance of these findings lies in their utility for long-term care management in PD. Anticipating which patients may suffer from greater postural decline could allow clinicians to implement early and tailored therapeutic strategies, targeting this symptom more effectively.

Furthermore, the study proposes mechanisms underpinning these observations, citing the body’s natural alignment system. Age and neurodegeneration can impair this system, leading the body to compensate in ways that can unfortunately exacerbate motor symptoms such as FFT.

Limitations, Opportunities, and Future Directions

While the study’s design was robust, it was not without limitations, particularly regarding its sample size. A larger participant group would enhance the power of the findings and help account for the high dropout rate – a common challenge in longitudinal research on progressive diseases.

The study’s conclusions also open doors for future research, with the potential for interventions focused on correcting patients’ subjective vertical positioning. This could take the form of physical therapy or the use of technologies such as virtual reality to recalibrate patients’ spatial orientation.


1. Mikami K., Shiraishi M., Kamo T., et al. (2019). Subjective Vertical Position Allows Prediction of Postural Deterioration in Patients with Parkinson’s Disease. Parkinsons Dis, 2019;2019:1875435. doi: 10.1155/2019/1875435.
2. Margraf N. G., et al. (2010). Camptocormia in idiopathic Parkinson’s disease: a focal myopathy of the paravertebral muscles. Movement Disorders. doi: 10.1002/mds.22780.
3. Bloch F., et al. (2006). Parkinson’s disease with camptocormia. Journal of Neurology, Neurosurgery, and Psychiatry. doi: 10.1136/jnnp.2006.087908.
4. Ashour R., Jankovic J. (2006). Joint and skeletal deformities in Parkinson’s disease, multiple system atrophy, and progressive supranuclear palsy. Movement Disorders. doi: 10.1002/mds.21058.
5. Bertram K. L., Colosimo C. (2016). Treatment of camptocormia with botulinum toxin. Toxicon. doi: 10.1016/j.toxicon.2015.06.004.


1. Parkinson’s Disease Posture Prediction
2. Forward Trunk Flexion Parkinson’s
3. Subjective Vertical Parkinson’s Study
4. Postural Decline in Parkinson’s
5. Anticipating Motor Symptoms in PD

Final Word

In conclusion, the noble pursuit to comprehend and combat the intricacies of Parkinson’s disease is undoubtedly interdisciplinary, seeking contributions from clinical research, neurology, rehabilitation, and more. The study carried out by Mikami and colleagues sheds light on a specific aspect of this complex puzzle – painting a clearer picture of the trajectory of postural impairment in Parkinson’s disease and potentially bolstering the repertoire of interventions for the betterment of patient care. As the SV angle rises, so does the clarion call for further investigations into this profound finding.