A systematic review in ‘Circulation,’ a journal of the American Heart Association, found that dog ownership is "protective against dying of any cause.". Dog ownership was associated with a 24% reduction in all cause mortality. , Mount Sinai endocrinologist Dr. Caroline Kramer. The review spanned over 70 years of research and included over almost 4 million people from several major countries. A separate study also found that people who owned dogs had better health outcomes after major cardiovascular events like heart attacks or stroke. Though both studies are observational and would require a clinical trial to be proven, the AHA marks the findings as significant. While these non-randomized studies cannot 'prove' that adopting or owning a dog directly leads to reduced mortality, these robust findings are certainly at least suggestive of this. , Dr. Glenn Levine, via AHA's scientific statement on pet ownership.