Abstract
Perceived social isolation (PSI) is a deficit in normal human social interaction, which has been associated with negative health outcomes. However, the precise mechanisms through which PSI influences human health are not fully known. This review aims at bringing out what is known about these pathways through which social isolation affects human health. We searched PubMed, Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica dataBASE (EMBASE), Psychological Information Database (PsycINFO), and Cochrane Library in addition to secondary references from primary journal articles for the most relevant and recent information concerning the research topic. The keywords used were perceived social isolation, loneliness, health outcomes, cardiovascular effects, neuroendocrine effects, depression, and cognitive decline, in animal and human populations. There are clear linkages between PSI and the cardiovascular system, neuroendocrine system, and cognitive functioning. PSI also leads to depression, cognitive decline, and sleep problems. The mechanisms through which PSI causes these effects are neural, hormonal, genetic, emotional, and behavioral. The effects of PSI on health are both direct and indirect. There is a complex interconnected network of pathways through which PSI negatively influences health. These hypothetical pathways using which the effects of PSI have been explained form the base on which further analyses can be carried out.