While I'm not aware of any study that ties intake of excess sugar to a decline in cognitive function, there was a study that linked diets with a high glycemic i

While I'm not aware of any study that ties intake of excess sugar to a decline in cognitive function, there was a study that linked diets with a high glycemic index to higher rates of depression, specifically post menopausal as the participants were new mothers: http://m.ajcn.nutrition.org/content/early/2015/06/24/ajcn.114.103846.abstract?papetoc#aff-1 http://m.ajcn.nutrition.org/content/early/2015/06/24/ajcn.11...