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Strong link between socioeconomic status across the life course and cognitive impairment, new study shows
By: Julie Frances Wilton
Last updated: Wednesday, 31 January 2024
Dr Dorina Cadar
There is a significant association between socioeconomic status (SEP) throughout life and the onset of mild cognitive impairment (MCI) in middle-aged adults, according to a pioneering study by Brighton and Sussex Medical School (BSMS) and published in theJournal of Epidemiology and Global Health.
The study's findings reveal that individuals who experienced upward, downward, or sustained lower socioeconomic status throughout their lives were significantly more prone to cognitive impairment compared with those who maintained a consistently higher socioeconomic status.
Individuals whose socioeconomic status remained low throughout their lives have an 85% higher risk of MCI compared to those whose socioeconomic status remained high. Those who moved from a higher to a lower socioeconomic group had a 70% higher risk of MCI, and even those who moved into a higher socioeconomic group were affected, with a 25% higher risk of MCI compared to those with always high socioeconomic status.
Senior author Dr Dorina Cadar, senior author and Senior Lecturer in Cognitive Epidemiology and Dementia at BSMS, said: "Our results highlighted an inverse association between life-course socioeconomic status and mild cognitive impairment, particularly emphasising the unique impact of socioeconomic mobility across one's life. Individuals with higher socioeconomic status often have better access to quality education, influencing cognitive development positively. Conversely, adverse childhood experiences associated with lower socioeconomic status, including limited access to resources and educational opportunities, may have enduring effects on cognitive function.
“This research highlights an underexplored aspect of cognitive health and emphasises the urgent need for comprehensive strategies to address socioeconomic disparities in cognitive wellbeing.”
Dementia has been the UK's leading cause of death since 2015, propelling a surge in research endeavours to comprehend its root causes. MCI is a condition characterised by noticeable cognitive decline that is greater than expected for a person's age and level of education but not severe enough to interfere significantly with daily life. It is often considered an intermediate stage between normal age-related cognitive decline and more serious conditions like Alzheimer's disease.
Around 10 to 15% of people who experience MCI with memory loss tend to develop dementia, most often Alzheimer’s disease; therefore, earlier case identification could offer more effective interventions in dementia prevention.
This latest study, drawing upon data from the National Child Development Study (NCDS), scrutinises the relationship between life-course SEP and MCI among 6,590 individuals aged 50 in Great Britain. Lower socioeconomic status persisting across one's life appears to be associated with heightened levels of stress and inflammation, potentially adversely impacting mental and cerebrovascular health, ultimately leading to cognitive impairment and, in some cases, dementia. The human brain possesses innate resilience, but the intricate relationship between socioeconomic status and cognitive impairment involves multifaceted dynamics.
Utilising data from the National Child Development Study (NCDS), also known as the 1958 British Birth Cohort, researchers traced the lives of 17,415 newborns born in England, Scotland, and Wales in a specific week of March 1958. The study aimed to investigate various topics, including social mobility, health, education and employment.
To construct life-course socioeconomic position measures, researchers utilised information on socioeconomic factors from different stages of birth, childhood and adulthood. The participants' fathers' social class at birth predominantly informed the assessment of socioeconomic position during childhood. The study delineated four distinct categories: ‘always high’, ‘upward’, ‘downward’, and ‘always low’, based on socioeconomic trajectories across their lives.
The study tracked people across 65 years of their lives and benefits from a life course investigation of cognitive assessments, education and lifestyle behaviours, as well as mental health, high blood pressure and other health conditions such as diabetes.
Socioeconomic status can also influence health behaviours such as smoking, diet and physical activity, potentially contributing to cardiovascular and metabolic conditions that elevate the risk of cognitive impairment.
Dr Cadar added: “This study underscores the pivotal role of socioeconomic factors in cognitive health and urges a life-course approach in public health policies targeting cognitive impairment. Understanding these mechanisms throughout life can spotlight the importance of addressing social determinants of health and advocating policies that mitigate health disparities.”
The study presents a substantial leap forward in unravelling the complex interplay between socioeconomic status and cognitive health, shedding light on pivotal factors that can influence cognitive impairment across the lifespan.