The science of what added sugars do to your body and your mind just gets more and more bleak. While going cold turkey on added sugars might be too big of a challenge (and could even backfire), you can focus on cutting back on your biggest sources. Pay close attention to drinks like soda, tea, and juice and check labels for "hidden" sources in products like yoghurt and ketchup.
Try the experiment: cutting out soda or added sugar.