Psychiatric symptoms and disorders in old age: prevalence, course and diagnostic thresholds

Abstract

The aim of this thesis was to study the epidemiology of some psychiatric disorders, as well as their corresponding subthreshold symptoms, in order to explore the border between psychopathology and normality in the general population of older people. Data came from population studies of older people in Gothenburg. Participants completed a semi-structured psychiatric interview and cognitive tests conducted by psychiatric research nurses. A key informant interview was also conducted. Psychiatric diagnoses were made using DSM-IV criteria. Dementia was an exclusion criterion for all studies. Study I examined the one-year prevalence of psychotic symptoms (delusions and hallucinations) in 70-82-year olds. The one-year prevalence of psychotic symptoms, as determined by expert review of available information, was 1.0% with no age or sex differences. Subthreshold symptoms (paranoid ideation and illusions) had a similar prevalence. A lower prevalence than in most previous studies may reflect methodological differences, age differences or secular changes in the prevalence of these symptoms. Study II and Study III examined the prevalence, correlates and course of specific phobia and subthreshold fears in 70-year olds followed-up at age 75 and 79 years. At age 70, specific phobia and subthreshold fears were present in 10% and 47%, respectively. Both were more common in women than in men. Specific phobia, but not subthreshold fears, was associated with other mental disorders. Specific phobia was associated with global functional impairment, but markedly less so than depression. The prevalence of specific phobia declined with age. Most individuals with specific phobia at age 70 did not have specific phobia during follow-up, but most had subthreshold fears, suggesting that these symptoms have a chronic course but with fluctuating severity and improvement with age. Study IV examined the prevalence and course of depression in 70-year olds who were followed-up at age 75 and/or age 79. At baseline and follow-up, participants were placed in one of four categories of depression (no depression, subsyndromal depressive symptoms, minor depression and major depression). The majority of baseline cases of major and minor depression were chronic or recurrent. Subsyndromal depressive symptoms at age 70 differed from no depression with respect to mental health correlates and prognosis. About half of individuals with major depression at follow-up had minor or subsyndromal depressive symptoms at age 70. These symptomatic risk groups could be suitable targets for prevention of major depression in older people.