Background: Depression is an important non-motor symptom of Parkinson’s disease (PD) that significantly impacts the daily activities of affected patients. Furthermore, the stooped posture that characterizes patients with PD has also been associated with depression. The purpose of this study was to investigate the relationship between the presence of depressive symptoms and body posture in patients with PD.
Methods: Forty-six patients with mild-to-moderate PD were recruited. The patients were divided into depression and no depression groups based on Beck Depression Inventory scores. All patients underwent kinematic analysis conducted in the upright standing posture with a motion capture system.
Results: There were no differences in clinical characteristics between the depression (n = 22) and no depression groups (n = 24). In the standing position, patients with depression showed anterior tilting of the head from the pelvis and an increased distance between head and pelvis. The severity of depression was correlated with the degree of flexion at the lower trunk level and the degree of anterior tilting of the head, neck, and trunk from the pelvis and base of support.
Conclusions: Patients with PD and depression showed increased flexion at pelvis level, which caused the trunk to tilt anteriorly. In addition, the severity of depression was correlated with the degree of anterior tilting of the head and trunk. These findings suggest that stooped posture, especially from the pelvis level, could be a marker of depression in patients with PD.
Parkinson’s disease (PD) is a slowly progressing neurodegenerative disease accompanied by non-motor symptoms such as psychiatric, cognitive, sensory, gastrointestinal, and autonomic symptoms [1–3]. Depression is an important non-motor symptom of PD, and the proportion of individuals with depression is significantly higher among patients with PD than in the general population . The reported prevalence of depression among patients with PD ranges from 2.7% to more than 90%, and the average reported prevalence is 35% [4,5]. Depression has a significant impact on sleep disorders, fatigue, and activities of daily living in patients with PD [6–8]. Schrag et al.  reported that depression was the factor most closely associated with quality of life in these patients. Posture, defined as the relative arrangement and position of body parts, is related to emotion [10,11]. An upright posture promotes positive thoughts, whereas a stooped or slumped posture promotes negative thoughts [12,13]. A stooped posture is included in the physical and diagnostic characteristics of patients with depression , and these patients exhibit greater cephalic flexure and thoracic kyphosis than healthy controls do . However, identifying depression in patients with PD can be difficult, considering that patients with PD and those with depression exhibit similar characteristics such as dampened facial expressiveness, fatigue, psychomotor retardation, loss of appetite due to a decreased sense of taste and smell, insomnia, a stooped posture, decreased walking speed, and short strides [4,14,15]. We therefore hypothesized that there are postural differences between patients with PD and comorbid depression and those without comorbid depression. This study’s primary objective was to investigate such between-group postural differences, and the secondary objective was to test for correlations between depression severity and body posture in patients with PD.