Residents of noisy and high-crime neighbourhoods are over a decade older biologically compared with those who live in low-crime areas, according to recent research.
The team from the Pittsburgh School of Health Sciences investigated how perceived neighbourhood quality affected the cells of residents, and concluded that those living in poor-quality areas had accelerated cellular ageing.
Lead author of the paper, Assistant Professor Mijung Park, said: 'Our team examined whether these environments also have a direct impact on cellular health. We found that, indeed, biological ageing processes could be influenced by socioeconomic conditions.'
Biological age, as opposed to chronological age, is determined by the length of the telomeres - protective pieces of folded DNA found at the ends of chromosomes. Each time a cell divides and copies its genetic information, the telomeres shorten, and this is thought to be one of the main mechanisms underlying ageing. Telomeres naturally shorten as we grow older, but the pace can also be accelerated by physical and psychological stresses.
It was already known that living in disadvantaged areas can damage physical and mental health, but the biological mechanism for this was not known. The research team analysed telomere length in the white blood cells of 2,902 Dutch people participating in the Netherlands Study of Depression and Anxiety, and they determined neighbourhood quality using measures of perceived neighbourhood disorder such as noise levels and fear of crime. The team adjusted for a suite of potential confounding factors, such as age, gender, weight and psychiatric indicators. They found that the telomere length of residents in high-crime areas were on average 174 base-pairs shorter than those of residents in low-crime areas.
Professor Park explained: 'The differences in telomere length between the two groups were comparable to 12 years in chronological age. It's possible that their cells are chronically activated in response to psychological and physiological stresses created by disadvantaged socioeconomic, political and emotional circumstances.'
The authors acknowledge that their study has some limitations, including being unable 'to make causal inferences'. But they say their work has 'established that certain neighbourhood characteristics matter for cellular ageing, over and above a range of individual attributes.'