Sense of Coherence (SOC) and the incidence of Dementia among Japanese elderly men and women: The AGES Study

Background: Associations between levels of sense of coherence (SOC) and health related outcomes such as mortality from and incidence of cancer and CVD have been well documented. However, little is known about the association between SOC and risks of dementia. This prospective cohort study attempted to examine the effects of SOC on risks of dementia incidence among older Japanese men and women living in the community setting.

Methods: Study subjects were 8,793 Japanese men and women aged 65+ years free from dementia at baseline 2003. Information about SOC evaluated by 13 items consisted of 3 subscales and other confounding variables were obtained through self-administered questionnaire, included in the Aichi Gerontological Evaluation Study (AGES), Japan. Three-year incidence of dementia was assessed through public long-term care insurance data bases and resident registry.

Results: A total of 298 newly diagnosed dementia cases (128 of male and 170 of female) were identified between follow-up period. The multivariable hazard ratios (HRs) of dementia incidence in the highest versus low SOC group were 0.41 (95%CI: 0.27-0.62) for total population. In addition, analysis on three SOC subscales showed significant association with incidence of dementia with dose responses, respectively. Furthermore, the inverse association between SOC and dementia onset did not change substantially when excluding incidences occurred after 0.5year, 1 year, and 1.5 years from baseline.

Conclusions: The higher level of SOC was associated with the lower risk of dementia incidence among Japanese elderly population, suggesting a protective role of positive psychological ability, specifically SOC on dementia onset.