These results suggest that neighborhood deprivation in urban areas, measured according to IMD score, is associated with cognitive function in older adults independent of their individual socioeconomic circumstances and level of education. This finding is in line with studies that have found a higher risk of depression in older people who live in more-deprived urban areas10,11
and poorer cognitive function in older people living in U.S. census tracts with low mean levels of education.15
Results were robust to adjustment for the effects of systolic blood pressure and of having had a stroke, suggesting that some other mechanism underlies the association between neighborhood deprivation and cognitive function.
This study is the first to use data from a nationally representative survey to assess the effects of neighborhood deprivation in urban areas on cognitive function in older adults. IMD scores, calculated based on national census data, are an objective measure of neighborhood deprivation, and the use of a similar approach has been proposed in the United States.45
IMD scores take into account a range of social factors and capture a broad range of factors about the neighborhoods in which respondents live. These deprivation scores were calculated at the level of the SOA, and SOAs, with a mean population of 1,500 individuals, are smaller than U.S. Census tracts, which have a population of between 2,500 and 8,000. This means that the data provided in relation to UK SOAs relate to smaller areas than those associated with U.S. Census tracts.
This study was not based on specific locales, as similar studies have been,15
but on the overall level of deprivation in the area in which an individual lived, and analysis involving locally specific data would add to what has been done here. SOAs represent administrative rather than natural or community-defined neighborhoods, but they were constructed using national census data with the express purpose of maximizing internal social homogeneity.28
Although deprivation and deprived neighborhoods are features of all societies, replication of these findings in other countries would be useful.
Other methodological issues ought to be borne in mind in assessing these findings. One relates to the problem of differentiating between members of the group of older individuals who have, according to contemporary standards, relatively low levels of education. More than 50% of those in the older age group in this study reported having left school at age 14 or younger. The differences in their levels of wealth and income will have captured some of the socioeconomic difference between them, but in terms of years of education and of highest level of qualification (as in the sensitivity analysis), there is no way to differentiate them.
Another methodological concern is that the sample used here includes only community-dwelling individuals and excludes those residing in institutions, those for whom cognitive function data were missing, and those for whom only proxy responses were available. This will tend to bias the results toward a population with relatively good cognitive function, although raw scores on the summary cognitive measure were normally distributed, indicating that the sample represented the full range of cognitive ability. Controlling for depressive symptoms suggests that depression, although associated with neighborhood deprivation in urban areas,10,11
does not account for the observed association between neighborhood deprivation and cognitive function, although it is not possible to eliminate the possibility that differences in cognitive function scores reflect depression or pseudo-dementia.
The suggestion that cognitive function in older people is lower in those living in deprived areas is consistent with the idea that older people may be particularly susceptible to neighborhood factors because many age in place9
—that is, they are long-term residents in communities that are in decline—and are more directly exposed to neighborhood factors.46
It is possible that older people with impaired cognitive function lack the resources, mentally and otherwise, to move out of neighborhoods in which levels of deprivation are increasing. The sensitivity analysis including duration of residence suggests that length of stay in a particular location is not an important factor in these results, but longitudinal data are necessary to address this directly.
A key unanswered question concerns the mechanisms by which neighborhood deprivation affects cognitive function in older people, mechanisms that are likely to be complex. Only aggregate IMD scores are available for the ELSA data set, and it would be useful to assess the effects of the different dimensions of neighborhood deprivation that make up the IMD; as has been suggested,47
examining specific features of areas would help to assess the relationship between neighborhood deprivation and individual out-comes. The sensitivity analysis reported suggests that access to resources, although of consequence, does not account for the difference in cognitive function associated with neighborhood deprivation. This is consistent with recent findings that socially disadvantaged neighborhoods do not necessarily have poorer access to health-related community resources,48
and similar analyses using geocoded data to assess levels of access to resources will be useful here. Including the effect of spouse’s or partner’s level of education made no difference to the respondent’s cognitive function, although a related factor that may explain the findings of this study relates to “the advantages of advantaged neighbors.”49
Living among people who are well educated and well off, rather than poorly educated and deprived, may affect one’s cognitive function in a way that operates over and above the effects of one’s own household socioeconomic circumstances.
The cross-sectional nature of the data used limits the conclusions that can be drawn. Analysis of longitudinal data might clarify some aspects of these findings. For example, the effect of neighborhood deprivation on cognition in men younger than 70 is less marked than in the other groups, and it is unclear whether, for example, biological factors, such as differing levels of subclinical cerebrovascular disease, or socioeconomic factors, such as the possibility that men in this age group work outside of the immediate neighborhood and thus experience less exposure to neighborhood factors, may account for this difference. In the absence of such data, it impossible to comment on causality; further research is necessary to identify suitable interventions to address the public health issues identified here.
This study has identified a number of aspects of neighborhood deprivation that are, and a number that are not, related to cognitive function in elderly people. Epidemiological work remains to be done in investigating the relationship between the micro- and macro-level factors impinging on health.50
In relation to these results, observing that living in a deprived neighborhood is associated with poor cognitive functioning is the first step toward identifying and confirming the specific aspects of neighborhood deprivation connected with this outcome and designing appropriate interventions to improve public health.