herpes, and influenza, but either slower or no change to the progression of AIDS. Based on the ELSA, a study found that loneliness increased the risk of dementia by one-third. Not having a partner (being single, divorced, or widowed) doubled the risk of dementia. However, having two or three closer relationships reduced the risk by three-fifths. Death A 2010 systematic review and meta- analyses found a significant association between loneliness and increased mortality. People with good social relationships were found to have a 50% greater chance of survival compared to lonely people ( odds ratio = 1.5). In other words, chronic loneliness seems to be a risk factor for death comparable to smoking, and greater than obesity or lack of exercise. A 2017 overview of systematic reviews found other meta-studies with similar findings. However, clear causative links between loneliness and early death have not been firmly established. Mental health Loneliness has been linked with depression, and is thus a risk factor for suicide. A study based on more than 4,000 adults aged over 50 in the English Longitudinal Study of Ageing (ELSA), looked at loneliness. Nearly one in five of those who reported being lonely had developed signs of depression within a year. Émile Durkheim has described loneliness, specifically the inability or unwillingness to live for others, i.e. for friendships or altruistic ideas, as the main reason for what he called egoistic suicide. In adults, loneliness is a major precipitant of depression and alcoholism. People who are socially isolated may report poor sleep quality, and thus have diminished restorative processes. Loneliness has also been linked with a schizoid character type in which one may see the world differently and experience social alienation, described as the self in exile. While the long-term effects of extended periods of loneliness are little understood, it has been noted that people who are isolated or experience loneliness for a long period of time fall into a "ontological crisis" or "ontological insecurity," where they are not sure if they or their surroundings exist, and if they do, exactly who or what they are, creating torment, suffering, and despair to the point of palpability within the thoughts of the person. In children, a lack of social connections is directly linked to several forms of antisocial and self-destructive behavior, most notably hostile and delinquent behavior. In both children and adults, loneliness often has a negative impact on learning