A study by Dr. Leana Wen, an emergency physician and clinical associate professor at George Washington University, found that watching television and other “mentally passive” sedentary activities can increase your risk of developing dementia. The study followed over 20,000 adults in Sweden over nearly two decades to find out how different types of sedentary behavior were associated with the risk of dementia. It found that individuals who spent more time in mentally passive activities had a significantly higher risk of development dementia, while time spent in mentally engaging activities while sitting was associated with a lower risk. The findings suggest that cognitive activity is important alongside physical activity. However, the study cannot prove cause and effect, as it's possible that people with better cognitive function are more likely to choose mentally engaging.