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Diagnostic Criteria Influence Dementia Prevalence

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Objective

The objective of this study was to compare the prevalence of dementia using different diagnostic systems, and to investigate the influence of the different diagnostic components (memory impairment, personality changes, definition of other intellectual functions) on the prevalence.

Methods

A general population sample of 1,019 elderly living in Gothenburg, Sweden was investigated by using the Comprehensive Psychopathological Rating Scale as well as specific assessments relevant for dementia diagnoses. Diagnoses were given according to the 9th and 10th version of the International Classification of Diseases (ICD-9, ICD-10) as well as the 3rd revised and 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM–III–R, DSM–IV). Further, “historical” criteria for dementia were applied as had been used in older studies.

Results

DSM–IV dementia occurred most frequently (9.6%), followed by dementia according to “historical” criteria (7.4%), DSM–III–R (6.3%), ICD-10 (3.1%), and ICD-9 (1.2%). The kappa values for the agreement between the diagnostic systems were between 0.166 and 0.810. The requirement of both long-term and short-term memory impairment in DSM–III–R and personality changes in ICD-10 explained most of the differences. When these requirements were held constant, DSM–III–R, DSM–IV, ICD-10 and “historical” criteria identified predominantly the same persons as demented (kappa: 0.810–1.000).

Conclusion

Prevalence of dementia varied widely depending on diagnostic classification system used. For DSM–III–R, DSM–IV, ICD-10, and “historical” criteria, the definitions of personality changes and combinations of memory impairment lead to differing prevalence rates, whereas the definitions of other intellectual functions have little impact.

Section snippets

Sample

The study sample was derived from the Prospective Population Study of Women (PPSW) and from the H70 Birth Cohort Study in Gothenburg, Sweden. Both samples were obtained from the Swedish Population Register, based on birth date, and included both persons living in private households and in institutions.

The PPSW had its baseline examination in 1968–69 on a representative sample of 1,467 women born in 1908, 1914, 1918, 1922, and 1930.16., 17. The participants were reexamined in 1974–75, 1980–81,

Prevalence of Dementia

The prevalence of symptoms used to make a diagnosis of dementia according to the different criteria is given in Table 1. The most frequent symptoms found were “decline in other cognitive abilities characterized by deterioration in judgment and thinking, such as planning and organizing” as defined by ICD-10 (28.1%), and “disturbance in executive functioning” as defined by DSM–IV. Other symptoms such as “coarsening of social behavior” or “emotional lability” were rare.

A total of 132 participants

DISCUSSION

In this population-based study, the prevalence of dementia varied widely depending on the diagnostic classification system used. These results are in agreement with other studies.5., 6., 7. Overall, there was only a weak overlap between the dementia cases identified by the different classification systems.

Possible sources of error must be taken into consideration. First, the attrition rate was relatively high. Participants had a slightly higher survival rate and were more often women, compared

References (27)

  • M Fichter et al.

    Dementia and cognitive impairment in the oldest old in the community: prevalence and comorbidity

    Br J Psychiatry

    (1995)
  • T Erkinjuntti et al.

    The effect of different diagnostic criteria on the prevalence of dementia

    N Engl J Med

    (1997)
  • S Riedel-Heller et al.

    Prevalence of dementia according to DSM–III–R and ICD-10

    Br J Psychiatry

    (2001)
  • Cited by (0)

    This work was supported by the Alzheimer's Association (Stephanie B. Overstreet Scholars IIRG-00-2159, Zenith Award ZEN-01-3151), the Swedish Research Council (11267), and the Swedish Council for Working Life and Social Research (2835, 0234, 2646).

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