Health and Fitness News and Notes

The more years of schooling you have, the higher your risk for nearsightedness.

Observational studies have suggested a link between education and myopia. But a new study used a genetic technique called Mendelian randomization to minimize the effect of several variables and provide stronger evidence of cause and effect.

Using eye examinations and questionnaires on education level, researchers used publicly available genetic data on 67,798 men and women in England, Scotland and Wales. They examined the many specific genetic variants linked to myopia and to the genetic predisposition to time spent in school, including higher IQ and other factors.

The researchers found that although genetic predisposition was a more powerful predictor of nearsightedness, years of education were strongly and causally linked to the condition. They acknowledge that the people in their database were generally healthier than the general population, which could lead to bias. The report is in BMJ.

The lead author, Dr. Denize Atan, a consultant senior lecturer in ophthalmology at the University of Bristol, said the mechanism is unknown but may have something to do with reduced exposure to natural daylight.

“Clues from other studies suggest that children who spend more time outside are protected from the onset and progression of myopia,” she said. “One recent study found that just 11 hours a week of daylight exposure seemed to be enough to slow onset and progression.”

More than 530,000 children have their tonsils or adenoids removed in the United States each year to prevent recurrent infections and sleep or breathing disorders. But a new study suggests the surgery may have long-term risks that in some cases outweigh any short-time benefits.

The report, in JAMA Otolaryngology — Head and Neck Surgery, compared 60,667 Danish children under 9 who had tonsillectomies, adenoidectomies or both with 1.1 million who had not had the surgeries. They were born between 1979 and 1999, and researchers followed their health for up to 30 years.

After controlling for many health factors, they found that tonsillectomy was associated with almost triple the relative risk of diseases of the upper respiratory tract. Adenoidectomy was associated with about double the relative risk of obstructive pulmonary disorder, upper respiratory tract diseases and conjunctivitis.

The surgery has some short-term benefits in cases of abnormal breathing, sinusitis and ear infections, but the long-term risks for those conditions were either significantly higher after surgery or not significantly different.

“This is the first study to look at long-term risks,” said the lead author, Sean G. Byars, a research fellow at the University of Melbourne. “With some kids, knowing that there are future risks may cause people to hold off, use pain medication and so on. Watchful waiting may be a good strategy when the condition is not too severe.”

Depression in older people tends to be more severe, last longer and be less likely to remit than the same disease in younger people, a new study concludes. The reason remains unknown, but it is apparently unconnected to known risk factors like social isolation or the chronic diseases of old age.

In a study published in Lancet Psychiatry, Dutch researchers followed 1,042 people ages 18 to 88 with diagnoses of major depression. They tracked four indicators of disease over two years: the likelihood of still having the diagnosis at the end of the study, how persistent symptoms were over time, the likelihood of reaching remission and the degree of improvement in depression severity.

By all four measures, depression worsened steadily with age, and people over 70 had worse outcomes than any other age group.

Factors other than age — loneliness, social support and network size, pain, number of chronic diseases, functional impairment, antidepressant use — explained only part of the effect. Old age by itself remained a significant risk factor.

“I think it’s important to note that depression is not the same across a lifetime,” said the lead author, Roxanne Schaakxs, a researcher at VU University Medical Center in Amsterdam. “It’s important to note the context in which it is happening. Old age really matters in the course of depression, and it really has to be investigated in more detail.”