Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Schizoid personality disorder is a personality disorder characterized by a lack of interest in social relationships, a tendency towards a solitary lifestyle, secretiveness, emotional coldness, and apathy. Affected individuals may also demonstrate a simultaneous rich, elaborate, and exclusively internal fantasy world. Learn more about Schizoid personality disorder, its causes, symptoms and treatments in the following pages.