In findings that support what many animal owners already know, Washington State University researchers conclude that spending time with dogs is good for people. So good, in fact, that canine companions can help address mental health disorders among humans. The study looked at teens in residential treatment centers for substance abuse. The participants' mood and attentiveness improved after the teens spent time with dogs, and symptoms of depression, attention-deficit/hyperactivity disorder and post-traumatic stress disorder dropped dramatically. Researcher Lindsay Ellsworth said canine companionship may stimulate the release of opioids.