The results show that age was the most important determinant of memory level and speed of decline. From the age of 75 onwards, scores began to fall more rapidly. After 85 the decline became more pronounced. Depression and chronic diseases such as diabetes also reduced the initial score. Loneliness, while influencing the starting point, did not accelerate the slope of cognitive decline.

The study also found that physical activity was associated with better initial memory scores. People who engaged in moderate or vigorous physical activity at least once a month recalled more words on immediate and delayed recall tests. This effect did not change the speed of decline, but it did raise the baseline level, which functions as a kind of “cognitive buffer.”

Although the study does not explore the causes of the link between loneliness and cognition, previous research has proposed plausible mechanisms. Loneliness is often associated with less social interaction, a factor that influences cognitive performance. It is also associated with increased risk of depression, which does directly affect memory tests. In addition, lonely people tend to have more health problems, such as hypertension or diabetes, which also affect cognitive function.

By 2050, according to United Nations projections, one in six people in the world will be over the age of 65. Societies are entering a stage where old age will no longer be the exception but will become the norm. Dementia, as well as other neurodegenerative diseases that appear with age, will be a major challenge for health care institutions.

This story originally appeared on wired.com.