There has so far not been enough formal research into combination therapy to have it accepted as a standard approach. One of the most recent studies conducted by UCLA involved observation of brain activity directly with EEGs. Over 200 children between the ages of seven and fourteen were treated either with the regular monotherapies, or with combinations of guanfacine and d-methylphenidate, over a period of eight weeks. The study found that those taking the combination got the most significant improvements in attention with improvements in brain activity related to better thinking skills. Improvements in ADHD symptoms were observed only in the combo therapy group. The researchers say combining stimulants with medicines like guanfacine could have long-term benefits for children and teenagers with ADHD – including those already showing improvement with one medication.