Incidence and risk factors of psychotic disorders in older people

Whilst it is known that the first episode of a psychotic disorder usually occurs during adolescence or early adulthood (Kessler et al., 2007), there is a considerable amount of people also experiencing the onset in old age, termed very late-onset of schizophrenic-like psychosis (VLOSLP).Over a year, between 0.1- 0.5% of the population past 65 years old are diagnosed with or have an existing diagnosis of schizophrenia (Howard, Rabins, Seeman & Jeste, 2000).

Robust research in regard to the variance in incidences of VLOSLP and its associated risk factors is important to inform public mental health in hopes of improving interventions for affected individuals. Yet, there is a limited amount of epidemiological research on VLOSLP. The studies that do investigate an onset of a psychotic disorder past 60 or 65 years old, are mostly cross-sectional studies of small samples with limited generalisability. Furthermore, their findings lack in replication. In tackling these limitations, Jean Stafford, one of our PhD students in the PsyLife team has conducted a systematic review on the research there is on incidence rates and different risk factors for VLOSLP. She also conducted a longitudinal cohort study looking into risk factors identified in previous research, including gender, age and sensory impairment as well as unexplored areas such as social economic status, migrant status, social isolation and trauma.

The systematic review and meta-analysis found 41 papers (dated between 1960 and March 2016) that looked at incidence cases of patients diagnosed with a psychotic disorder past 65 years old, not including cases related to dementia, organic and drug-induced psychoses. The majority of these papers were rated of high and average quality, and 25 were included for quantitative analysis. The pooled incidence rate showed that, every year, 7.5 out of 100 000 people over 65 years old were diagnosed with schizophrenia. Moreover, psychoses related to an affective disorder had a yearly rate of 30.9 new cases per 100 000 people. Incidence rates for non-affective psychoses differed largely between studies, and a pooled estimate was not possible. However, the cohort study offers some clarification as it investigated only non-affective psychotic disorders.

The cohort study consisted of over 3 million participants past age 60, all Swedish residents born between 1920 and 1949. Large-scale data collection was possible as every resident in Sweden is given a national identification number that is recorded within a range of health and administrative services. This revealed an incidence rate for non-affective psychotic disorders of 37.66 per 100 000 people every year.

Stafford also investigated the influence of gender and age. The systematic review found reports that women were more likely to be diagnosed than men past age 65 within all branches of psychotic disorders analysed (non-affective, affective psychoses and schizophrenia). The cohort study supported this, with participants diagnosed with a non-affective psychotic disorder past 60 years old being 60% female. In regard to age, the systematic review revealed previous research has been mixed. However, the cohort study revealed a significant increase with age, with differing patterns between men and women. Past 80 years old, women were at risk for VLOSLP at an accelerated rate.

The cohort study also collected data on other possible risk factors, such as migrant status, income, family and sensory impairments. Migrants from Africa, North America and Europe were at elevated risk compared to the rest of the population. This is an association also found in younger populations , possibly explained by the stressors encompassed in migration. Furthermore, low income at age 60 significantly predicted a higher future risk of VLOSLP. In an investigation of family history, it was found that participants with children diagnosed with a psychotic disorder were twice as likely to have VLOSLP. Looking at social isolation; participants with no children and/or no partner 2 years before exiting the study were at elevated risk. Experiencing the death of a partner 2 years before also led to increased risk, whilst the death of a child before age 18 had no association and the death of a child at infancy had weak evidence for elevated risk. These could be indicators of the influence of trauma. Contradictory to previous research (Cooper & Porter, 1976; Cooper et al. 1974), participants with sensory impairments were less likely have VLOSLP compared to the general Swedish population. However, this result could reflect an under-detection of psychiatric disorders in people with physical health issues (Roberts, Roalfe, Wilson & Lester, 2007)

In conclusion, these results indicate that people with VLOSLP were more likely to have social disadvantages, such as lower income and social isolation. This could be interpreted two ways; either there is causal link where the stressors of inequalities lead to increased risk of a psychotic disorder, or that those with premorbid symptoms of a psychotic disorder will subsequently suffer disadvantages due to lower functioning, although VLOSLP patients have been shown to have higher premorbid functioning (Castle et al., 1997). Older women are at particularly prominent risk, indicating this is a group deserving of more clinical recognition.

Full version of the systematic review can be found here, and the cohort study here.

 

PsyLife References:

 

Other references:

  • Castle, D.J., Wessely, S., Howard, R., et al. (1997). Schizophrenia with onset at the extremes of adult life. Int J Geriatr Psychiatry, 12, 712–717.
  • Cooper, A. F., Curry, A. R., Kay, D. W., Garside, R. F. & Roth, M. (1974). Hearing loss in paranoid and affective psychoses of the elderly. Lancet 2, 7885, 851–54.
  • Cooper, A. F. & Porter, R. (1976). Visual acuity and ocular pathology in the paranoid and affective psychoses of later life. Journal of Psychosomatic Research 20, 107–114.
  • Howard, R., Rabins, P. V., Seeman, M. V., & Jeste, D. V. (2000). Late-onset schizophrenia and very-late onset schizophrenia-like psychosis: An international consensus. American Journal of Psychiatry, 157, 172–178.
  • Kessler, R. C., Amminger, G. P., Aguilar-Gaxiola, S., Alonso, J., Lee S., & Utsun, T. B. (2007). A controlled family study of late-onset non-affective psychosis (late paraphrenia). The British Journal of psychiatry, 170, 511-514.
  • Roberts, L., Roalfe, A., Wilson, S., & Lester, H. (2007). Physical health care of patients with schizophrenia in primary care: a comparative study. Fam Pract, 24, 34–40.

 

 

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