Vulnerability and Social Functioning in Schizophrenia

This thesis offers a broad approach in elucidating biological risk factors, as well as psychological and social functioning in schizophrenia. The aims are as follows: (I) investigate the association between birth characteristics and schizophrenia, (II) study the association between levels of neurotransmitter neuropeptide Y (NPY) in cerebrospinal fluid (CSF), social function and longitudinal outcome in schizophrenia, (III) compare social functioning of patients with schizophrenia with their biological siblings and (IV) explore how siblings to patients with schizophrenia perceive the sibling relationship and their role. Paper I was a cohort analysis of 11,360 same-sexed twins in which obstetric records were used. Low birth weight and small head circumference were associated with later development of schizophrenia. To some extent the results persisted in the within-pair analyses conducted on 82 pairs discordant for schizophrenia. Fifty-six patients with schizophrenia were included in paper II. Levels of NPY in CSF correlated to social competence at index admission. For each standard deviation increase in baseline NPY, there was a concomitant increased risk of being unemployed, having moderate or severe symptoms or recent hospitalization at the 3-year follow-up. In paper III, social functioning was investigated using the Swedish version of the videotaped test Assessment of Interpersonal Problem Solving Skills (AIPSS) in 70 participants (25 patients with schizophrenia, 20 siblings and 25 randomly selected controls). The patients presented severe deficits in social functioning. The siblings expressed subtle impairments in nonverbal language but did not generally differ from the controls. To explore the siblings’ perspective on schizophrenia a qualitative study was conducted with interviews of 16 siblings in paper IV. A unifying major theme was an emotional sibling bond. Siblings developed several coping patterns, including avoidance, isolation, normalization, care giving and grieving. A third major theme consisted of the fear of inheriting schizophrenia. In conclusion, fetal growth, altered levels of NPY in CSF and subtle impairments in nonverbal social behavior might be important risk factors in schizophrenia. Patients with schizophrenia revealed extensive impaired social functioning, and from the siblings’ perspective, a brother or sister’s diagnosis of schizophrenia seems to have a profound psychological impact on the siblings