Very late-onset schizophrenia-like psychosis: incidence, risk factors and subsequent dementia

Introduction People aged 65 years and above are frequently excluded from research on the epidemiology of non-affective psychotic disorders; consequently, little is known about the incidence of psychotic disorders in older people. In this thesis, I characterised the incidence of very late-onset schizophrenia-like psychosis (VLOSLP) in relation to socio-demographic factors, and I investigated the association between VLOSLP and subsequent dementia. Methods In Chapter 2, I conducted a systematic review and meta-analysis to synthesise published data on VLOSLP incidence. In Chapter 4, I investigated the incidence of VLOSLP in a Swedish population-based cohort. I conducted a matched cohort study to examine the rate of subsequent dementia in VLOSLP in Chapter 5. In Chapter 6, I assessed the feasibility of a case-control study examining social isolation, loneliness and social cognition in VLOSLP. Results In Chapters 2 and 4, I demonstrated a substantial burden of VLOSLP incidence, with a higher rate in women and migrants. Additionally, in Chapter 4, I found a higher rate of VLOSLP in those with a lower disposable income and those with no partner or children. The rate of subsequent dementia was higher in those with VLOSLP relative to age and calendar-period matched comparisons in Chapter 5. In Chapter 6, I found that the feasibility of the case-control study was limited due to challenges in recruiting patients with VLOSLP. Discussion In this thesis, I characterised the incidence of VLOSLP and identified several potential socio-demographic risk factors and outcomes associated with VLOSLP. My findings indicate that VLOSLP may be more common than was previously realised and suggest that the association between the environment and psychosis may persist into late life, opening up new areas for future investigation. Findings of a higher rate of dementia following VLOSLP may be relevant to clinicians in considering monitoring and treatment options.