INTRODUCTION
Musculoskeletal disorders, including spinal diseases, are risk factors for dementia. The patient with adult spinal deformity shows impairment in standing and walking, possibly leading to dementia. However, the relationship between adult spinal deformity and dementia is unclear. This study aimed to clarify whether a sagittal imbalance of the spine is a risk factor for the development of dementia.
METHODS
This study was a prospective cohort study. The subjects were aged 65 or older and had undergone specific health examinations in the community in 2010. Standing whole-spine lateral radiographs were taken to measure sagittal vertical axis (SVA), pelvic tilt (PT), pelvic incidence (PI), and lumbar lordosis (LL). The primary endpoint was a new occurrence of dementia over five years. Dementia development between 2010 and 2015 was investigated using official long-term care insurance certification data. The subjects were divided into groups by SVA using the SRS-Schwab classification (SVA<40, 40-95, 95<), and the incidence of new dementia was compared over five years. Statistical analyses were performed using the chi-square test, Wilcoxon test, and multiple logistic regression analysis. A significance level of less than 5% was considered significant.
RESULTS
Among 593 subjects (230 males and 363 females, mean age 73 years), dementia occurred in 8 (2.2%) in the SVA <40 group, 12 (6.2%) patients in the SVA 40-95 group, and 5 (14.7%) in the SVA >95 group. The incidence of new dementia was significantly higher in the 40-95 and >95 groups than in the <40 group (p<0.05). Multivariate analysis with age, gender, depression, daily exercise, diabetes, knee osteoarthritis, and smoking as adjustment factors showed that the odds ratio [95% confidence interval] of SVA40-95mm to SVA40mm was 3.0 [1.2-7.8] and that of SVA >95mm was 10.0 [2.7-36.6]. These results indicated that spinal sagittal imbalance with SVA>40mm was independently associated with the new onset of dementia (p<0.05).
DISCUSSION
The results of this study indicate that sagittal imbalance is an independent risk factor for dementia in the general population. Adult spinal deformity with sagittal imbalance may be associated with the development of dementia through the decrease of activity due to the deformity itself, as well as impaired standing and gait. Prevention and treatment of adult spinal deformities may lead to a decrease in dementia.