Associations Between Striatal Dopaminergic Integrity and Gait Quality

Gait quality aspects beyond pace like walking smoothness (harmonic ratio), regularity (entropy rate), and complexity (Lempel-Ziv complexity) may be useful in capturing the motor control strategies important in successful everyday walking. Dopaminergic (DA) integrity in the central nervous system plays a crucial role in motor function. Age-related declines in dopamine within the striatum may contribute to concurrent declines in gait quality in older adults without Parkinson’s. We investigated the relationship between striatal DA integrity and gait quality in an exploratory analysis. In 199 participants (Age: 75.00 years (4.63), Sex: 123 Females (61.81%) BMI: 28.22 (5.41)), DA integrity was measured using [11C]DTBZ PET imaging estimating the striatal binding site density of the type 2 Vesicular Monoamine Transporter (VMAT2). Accelerometers on the L3 segment of the lumbar spine during walking over 15 meters measured entropy rate, Lempel-Ziv complexity, wavelet entropy, and harmonic ratio of the signal in the medio-lateral (ML), anterior-posterior (AP), and vertical anatomical directions. Multiple linear regression estimated the cross-sectional association between the striatal region of interest [11C]DTBZ binding density and each gait measure, adjusted for age, sex, BMI, race, education, and hours walked per week. Before correction for multiple comparisons, higher [11C]DBTZ binding density in the precommissural dorsal caudate was associated with higher entropy rate in the AP anatomical plane (β: 0.033, 95% CI [0.001, 0.066]). Higher [11C]DBTZ binding density in the anterior ventral striatum was associated with lower gait speed (β: -0.112, 95% CI [-0.213, -0.012]). Additionally, before correction, higher [11C]DBTZ binding density in the postcommissural putamen was significantly associated with lower wavelet entropy in the vertical anatomical plane (β: -0.084, 95%CI [-0.153, -0.015]). After Bonferroni correction no relationships between dopaminergic integrity in the striatum and gait quality characteristics were significant. Novel accelerometry gait characteristics and PET imaging are powerful tools for understanding mechanisms of age-related neurological decline. Mitigation of mobility limitations remains an important public health focus.