 This is a single center study and the UC Davis MIND Institute for Autism Spectrum Disorder ASD patients aged between 2 years and 5 years old inclusive funded by the Health Resources and Services Administration HRSA. It is a double-blind control trial of sertraline Zoloft, an anti-depressant typically used in the treatment of depression, obsessive-compulsive disorder, panic disorder, and other conditions. The researchers are investigating the use of this selective serotonin reuptake inhibitor SSRI in ASD because a retrospective study has shown significant improvements in language and social deficits. There is also emerging evidence regarding the stimulation of brain-derived neurotrophic factor BDNF and the stimulation of neurogenesis when an SSRI is given early on in the development of animal models of Down syndrome. The researchers hope to see improvements in language stimulation, social gaze and social reciprocity, spatial attention, and a decrease in autistic behaviors. 