Loneliness, sometimes referred to as “perceived social isolation,” is defined as a subjective experience of social isolation. Loneliness has been shown to be related more to the quality of social relationships than to the quantity, and is typically characterized by feelings of social disconnection (e.g., being misunderstood by others). It occurs when there is a discrepancy between desired and actual amounts of social interaction. Humans are a social species and have a fundamental need to belong. Feelings of loneliness have been perceived to be early warning signals of potential threats to psychological health (akin to physical pain in physical health problems). Loneliness is associated with an increased risk of various health conditions (e.g., increased inflammation, decreased immunity) and can occur in transient and chronic forms across the lifespan.
In the last few decades, there has been an increase in scientific studies in loneliness and much of this research stemmed from a social neuroscience approach (see work by Cacioppo). The onset of loneliness is thought to motivate an individual to seek connectedness with others; however, symptoms of mental illness often involve withdrawal from the social world. A growing interest in the relationship between loneliness and mental health disorders is therefore not surprising and was first identified as an important relationship in the late 1950s. Psychoanalyst Frieda Fromm-Reichmann highlighted the devastating impact of loneliness on patients with schizophrenia. In more recent times, researchers have used a neuroscience approach to further clarify the relationship between social withdrawal/isolation and positive symptoms of psychosis (see Hoffman’s social deafferentation hypothesis).
The psychological consequences of loneliness, however, remain under examined by researchers. It is plausible, but remains unclear, that loneliness is a transdiagnostic factor across different mental disorders that raises the risk of mental health problems, increases the severity of symptoms, maintains diagnostic status, or all of the above. Loneliness is associated with various mental disorders, including depression, social anxiety disorder, and obsessive–compulsive disorder (1), and most of the research on loneliness and mental health has focused on its relationship with depression (2).
To date, there has been no published study that has developed an evidence-based loneliness intervention in individuals with psychosis. A meta-analytic review of interventions aimed at reducing loneliness in a range of different populations surprisingly included only five studies with individuals with mental health symptoms, and none of the studies were specific to psychosis (3). There is, however, emerging research that highlights the deleterious effects of loneliness in individuals with psychotic disorders. In the second Australian national survey of psychosis (N = 1825), 80.1% of adults aged between 18 and 34 years, diagnosed with a psychotic disorder endorsed perceived loneliness; 37.2% of these adults identified loneliness as a barrier to recovery (4). While many psychosocial interventions are aimed at introducing new social supports (e.g., befriending) or providing social skills training (SST) for people with psychotic disorders, there has been no known study that specifically targets loneliness.