In the Stirling County Study of the prevalence of depression and anxiety, the questions used to diagnose depression in 1952 were modified in 1992.
Which of the following best explains why this was done?
C. The Stirling County Study is one of the foremost psychiatric epidemiological studies. It was conducted on cross-sectional samples of the population living in Stirling County, Canada, in 1952, 1970, and 1992. The epidemiological data was revisited in 2000 and it showed that vernacular changes in semantic use of terms such as dysphoria could affect results of epidemiological surveys. Using the same diagnostic system (called DPAX-1) in 1952 and 1970, no increases in point prevalence of depression were noted, but when the same criteria were employed in 1992 a drop in prevalence was noted. This was due to a change in use of the term dysphoria in the studied population; this term went out of use by 1992, leading to a drop in the sensitivity of the diagnostic instrument DPAX-1. By increasing the number of questions exploring the mood state and changing the diagnostic system (to DPAX-2), similar prevalence rates were detected in 1992. Note that though the diagnostic categories changed between 1952 and 1992 this did not have a direct influence on the Stirling County Survey, which used a purpose-built instrument to measure the prevalence.
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Which of the following epidemiological studies suggested that lifetime prevalence of depression has remained unchanged over recent decades?
C. Various studies, including NCS and its replication NCS-R, NESARC (National epidemiological Survey on Alcohol and Related Conditions) and ECA (Epidemiological Catchment Area Study), have implicated that lifetime prevalence of depression is changing. The Stirling County Study did not reveal such a significant change in rates of depression. This apparent change in prevalence could be attributed to the use of different diagnostic instruments. DIS (Diagnostic Interview Schedule), used in the ECA, and its modified improvised versions used in other studies relied on recall of lifetime prevalence. Significant recall bias is expected for a progressively older cohort who will deny or could not recall their depressive episodes. This might have resulted in a spurious effect. NCS used DSM IIIR (10.1% depression 12-month period prevalence) while its replication used DSM IV (8.7% depression prevalence), with its clinical impairment and distress criteria making it possible that less patients will be diagnosed with DSM IV. In fact, it was later shown that if DSM IV criteria were reapplied then prevalence of depression drops from 10.1% to 6.4% in the NCS 1994. In addition, NCS excluded all those above age 54 but included a 15 to 17 age group (in contrast to NCS-R), inadvertently choosing the most prevalent population that might have inflated the prevalence value. These flaws were absent in NESARC, which showed nearly doubled point prevalence estimate of depression from 3.3 to 7% from 1992 to 2002.
The prevalence of hallucinatory experiences in healthy British respondents from community samples is estimated to be around:
A. A nationally representative sample of nearly 8500 adults aged 16–74 years living in private households in Great Britain were interviewed by lay interviewers and were classified according to their score on the Clinical Interview Schedule–Revised (Psychiatric morbidity survey, Office of National Statistics). The Psychosis Screening questionnaire was used to collect selfreported symptoms of psychosis. In the sample, 4.2% said that there had been times when they heard or saw things that other people could not, but only 0.7% reported hearing voices saying quite a few words or sentences when there was no-one around that might account for it.
A sample of healthy British community respondents was surveyed for self-reported psychiatric symptoms. Most respondents would rate themselves to have had which of the following symptoms?
B. In the Office of National Statistics–Psychiatric Morbidity Survey in the UK, a selfreported instrument, called the Psychosis Screening Questionnaire, was used to detect selfreported psychotic symptoms. The questionnaire measured symptoms in fi ve domains, namely, hallucinations, hypomania, strange experiences, paranoia, and thought insertion. Nearly half of the respondents thought that they experienced at least one hypomanic symptom when questioned, but, when explored further, more than half of the respondents had valid reasons for feeling very happy for many days without a break. Only 0.6% reported their friends or relatives commenting on such a prolonged ‘happy’ state.
In epidemiological surveys of preschool children, which of the following factors observed around age 3 of a child predicts behavioural difficulties by age 8?
C. Surveys of preschool children have recorded a high prevalence of problem behaviours. The most commonly reported problem is that of bedwetting, seen in around 37% of a sample. Boys and girls show equal prevalence of these problems while those with expressive language disorders show more behavioural difficulties. Maternal depression and family discord at 3 years strongly predict behavioural disorder by the age of 8.
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