“…The mean age range of individuals varied from 21.5 years (Chamberlain et al, 2012) to 76.8 years old (Galanis et al, 1997). Several studies compared individuals within particular age groups, such as young adults (Chamberlain et al, 2012;Deary et al, 2003;Paelecke-Habermann et al, 2013;Smolka et al 2004;Yakir et al, 2006) middle aged adults (Carim-Todd et al, 2015;Durazzo et al, 2012;Friend et al, 2005;Hatta et al, 2006;Kalmijn et al, 2002;Luhar et al, 2013;Sabia et al, 2012, Schinka et al, 2002, and elderly (Chen et al, 2003;Galanis et al, 1997;Hill et al, 1989;Launer et al, 1996;Razani et al, 2004). Average years of education varied from 2.9 years (Chen et al, 2003) to 16 years (Carim-Todd et al, 2015).…”