Friendship can be defined as a “distinctively personal relationship that is grounded in a concern on the part of each friend for the welfare of the other, for the other’s sake, and that involves some degree of intimacy” 
. The definition of friendship can vary significantly in different geographical and cultural contexts but also due to personal factors, (attachment style, gender, previous experiences) 
. Yet, the role of friends as a source of social support is becoming increasingly important in contemporary society 
, as a consequence of changes in family structure and of the increased number of people living alone 
. It has been widely recognized that having friends provides patients with a mental disorder with emotional and practical support and helps them to cope with life stressors 
. Relationships with friends may also positively affect physical and mental health by improving health behaviours and help seeking and confer psychological benefits for depression, self efficacy, self esteem, coping, and morale 
People with psychotic disorders tend to have fewer friends and social relationships compared to the general population and to patients with other mental and physical disorders 
While many factors, such as deficits in neurocognition and social cognition, unemployment, financial difficulties and stigma are likely to reduce patients’ social functioning 
, different symptoms of psychotic disorders have been linked to patients’ difficulties in establishing and maintaining social contacts. Social withdrawal of patients with psychotic disorders has been suggested to be an attempt at avoiding excessive stimulation and subsequently relapse. Hansen and colleagues 
proposed a distinction between passive social withdrawal, which may be mostly related to negative symptoms, and active social avoidance, which has been linked to positive symptoms. The lack of motivation which is part of the negative symptoms dimension may play a significant role in reducing contact with friends 
. As regards the other symptom domains of psychosis, depressive and anxiety symptoms may reduce patients’ drive towards social activities and contacts 
; thought disorders may influence patients’ language and ability to share their thoughts and feelings with others 
; high levels of excitement and activation may make patients appear unpredictable and dangerous so that others avoid contact and longer relationships with them 
; high levels of hostility have been found to predict worse social integration, defined as number of contacts and significant relationships 
However, although many studies have assessed the relationship between psychotic symptoms and patients’ global social networks, few data are available on the associations of symptoms specifically with friendship, with its characteristics of an intimate and supportive relationship.
To our knowledge, only one mixed-methods study, carried out on 151 patients with schizophrenia in south England, has specifically focused on relationships with friends of patients with schizophrenia 
finding an association between levels of both positive and negative symptoms and contacts with a friend. Other studies 
found a moderate correlation of negative symptoms and hostility with social functioning and involvement in leisure activities in the community that were correlated with friendships in relatively small samples (n
56 and n
Evidence from larger samples is necessary to further understand how different symptoms are specifically associated with contacts with friends. Given the protective effects of friendship, interventions to improve patients’ friendships and, as a consequence, social support, clinical outcomes, and quality of life may need to consider specific symptom dimensions.
This study assessed, through a pooled analysis of individual patient data from four Europe-wide multicentre studies, the association of five symptom dimensions of psychotic disorders (negative symptoms, thought disorders, depression/anxiety symptoms, activation and hostility) with having a close friend and contacts with friends in the community. As age and gender have been found to be associated with patients’ social contacts in previous studies 
, we also investigated whether the associations between symptoms and having a friend and contacts with friends were similar for males and females and in different age groups. Initially, our analysis included all patients with psychotic disorders, diagnosed according to ICD-10 criteria (F20–29). In a second phase, we performed a sensitivity analysis including only patients with schizophrenia (F20).