Long-term shift work ages the brain, a new study claims today. Researchers found that working shifts leads to a loss of memory and an impaired ability to think. A decade or more working rotating shifts was associated with a loss of brain function equivalent to six and a half years of the normal decline in thinking and memory associated with ageing, they showed.Stopping shift work led to gradual recovery - but one that took at least five years, said scientists. Disruption of the body clock, which is based on natural day and night cycles, may cause stresses that may affect brain functioning, the researchers believe.Other studies have linked vitamin D deficiency due to reduced exposure to sunlight to poorer mental ability. Writing in the study, lead researcher Dr Jean-Claude Marquie, from the University of Toulouse, France, concluded: 'Shift work chronically impairs cognition, with potentially important safety consequences not only for the individuals concerned, but also for society.' The scientists assessed more than 3,000 workers from southern France who had their mental abilities tested on three occasions over a 10-year period.Participants were aged 32, 42, 52 and 62 at the time of the first test in 1996.Around a fifth had worked a shift pattern that switched between mornings, afternoons and nights.Shift workers had lower average scores for memory, processing speed and overall brain function than those working normal office hours. Stopping shift work led to gradual recovery - but one that took at least five years, scientists said Compared with people who had never worked rotating shifts, participants employed this way for 10 or more years had lower overall thinking and memory scores.The level of impairment was equivalent to six and a half years of age-related cognitive decline, said the researchers.The international team of scientists, who included British researchers from the University of Swansea, said the problems increased with the length of time people worked shifts. After 10 years of rotating shift work the association became 'highly significant'. However, there was evidence that the deficits were reversible. People who stopped working shifts recovered their lost mental function after at least five years.The researchers wrote: 'Measures should be considered that mitigate the impact that prolonged exposure to shift work has on cognitive abilities, including switching to normal day work.' The study was published in the journal Occupational and Environmental Medicine.The findings add to a body of research about how shift work damages health.Studies have shown night shifts triple the risk of heart disease while mental health problems, cancer, depression, diabetes, obesity and strokes have also been linked to poor sleeping habits. In January, British researchers found working shifts could damage almost 1,500 genes - explaining why it has been linked to such a wide range of health problems. They found disrupting the body’s natural 24 hour cycle disturbed the rhythm of genes. The UK’s Health and Safety Executive has now commissioned researchers in Oxford to explore the relationship between chronic disease and shift work, which is expected to be completed in December 2015. source
