Social mobility extends years lived without dementia, Japanese study reveals

Upward social mobility may ward off dementia, according to a new study. Dementia, a collective term for conditions marked by memory loss and diminished cognitive functioning, strains health care systems and devastates quality of life for patients and their families.

Research thus far has found correlations between socioeconomic status (SES)—parent’s assets, education level, income, and work status—and susceptibility to dementia, and SES changes throughout a person’s life, known as social mobility, seem to influence this risk; however, scientific evidence is lacking.

The new study, led by Osaka University researchers and published in JAMA Network Open, provides data-backed evidence that upward social mobility is associated with a lower dementia risk. Specifically, a downward SES transition was associated with the highest loss of healthy longevity from age 75 onward in their lifetime. Yet, an upward transition was linked with the longest period of healthy longevity. Interestingly, these results from an upward transition are more favorable than those with stable high SES since childhood.

“Thanks to a large and robust dataset, our findings solidify the association between socioeconomic mobility and dementia risk,” the study’s lead author Ryoto Sakaniwa says.

“Our finding that upward social mobility throughout a person’s life correlates with a prolonged period of dementia-free aging means that improving socioeconomic conditions could be a key to dementia prevention and healthier longevity.”

The researchers used data from the Japan Gerontological Evaluation Study, which followed 9,186 participants aged 65 and over from 2010 to 2016.

The study employed unsupervised clustering analysis and data-driven classification to analyze changes in participants’ SES throughout their lives. The analysis identified six distinct SES transition patterns. The researchers used a national registry of long-term nursing care services to determine dementia incidence, which enabled a detailed examination of the relationship between these transitions and dementia risk.

The analysis found that upward SES transitions were associated with a notably lower risk of dementia incidence compared with stable SES patterns. Conversely, downward SES transitions had a significantly increased risk.

The study also explored the mediating effects of lifestyle behaviors, comorbidities, and social factors on the association of SES transitions and dementia risk. These factors were found to play significant roles in mediating that risk, particularly physical characteristics and lifestyle behaviors in upward transitions and social factors in downward transitions.

“Future research should delve deeper into the mechanisms by which SES influences cognitive health, including potential interventions for mitigating dementia risk,” senior author Hiroyasu Iso says.

“Understanding the nuances of how SES and its transitions impact dementia is vital for developing targeted strategies addressing underlying socioeconomic factors throughout one’s life.”