(S (S (NP (BASENP (DT A) (JJ recent) (JJ scientific) (NN review)) (PRN (COMMA ,) (VP (VP (VBG involving) (NP (QP (ADVP (RBR more) (IN than)) (NN 300,000)) (NNS people))) (PP (IN across) (BASENP (JJ several) (JJ previous) (NNS studies)))) (COMMA ,))) (VP (VBZ has) (VP (VBN revealed) (SBAR (IN that) (S (NP (BASENP (JJ inadequate) (JJ social) (NN networking)) (CC and) (BASENP (JJ frequent) (NN isolation))) (VP (MD can) (VP (VB have) (NP (NP (BASENP (JJ negative) (NNS effects)) (PP (IN on) (NP (BASENP (DT a) (NN person) (POS 's)) (NN health)))) (ADJP (JJ equal) (PP (TO to) (NP (BASENP (DT that)) (VP (VBN caused) (PP (IN by) (NP (BASENP (NN smoking)) (CC and) (BASENP (NN alcohol) (NN abuse)))))))))))))))) (PERIOD .))