Research and development expenses for the three months ended June 30, 2017 were $ 34.2 million compared to $ 20.5 million for the same period last year. For the six months ended June 30, 2017 and 2016, research and development expenses were $ 69.6 million and $ 43.3 million, respectively. The increase in research and development expenses during the 2017 periods compared to 2016 was primarily due to increased clinical costs related to the ACADIA schizophrenia and depression studies initiated in the fourth quarter of 2016. In addition, additional employees and related costs were incurred.