Consistency of clinical diagnosis of dementia in NEDICES: A population-based longitudinal study in Spain

J Geriatr Psychiatry Neurol. 2009 Dec;22(4):246-55. doi: 10.1177/0891988709335794. Epub 2009 May 5.


Background: Few longitudinal studies have verified the clinical diagnosis of dementia based on clinical examinations. We evaluated the consistency of the clinical diagnosis of dementia over a period of 3 years of follow-up in a population-based, cohort study of older people in central Spain.

Methods: Individuals (N = 5278) were evaluated at baseline (1994-1995) and at follow-up (1997-1998). The evaluation included a screening questionnaire for dementia and a neurological assessment.

Results: Dementia screening consisted of a 37-item version of the Mini-Mental State Examination (MMSE) and the Pfeffer Functional Activities Questionnaire (FAQ). Study neurologists investigated those participants who screened positively (N = 713) as well as 843 who had screened negatively to test the sensitivity of the screening instruments or because they had a positive screening for other chronic neurological diseases. We detected 295 patients among those who screened positive and 13 among those who screened negatively. Three years follow-up evaluation demonstrated 14 diagnostic errors at baseline (4.5%) leading to a final number of 306 patients with dementia. The corrected prevalence of dementia was 5.8% (95% confidence interval [CI] 5.2-6.5).

Conclusions: The diagnosis of dementia was highly accurate in this population-based, Spanish cohort study, and our prevalence figures agree with other European surveys. Given the high cost and difficulties of population rescreening and its relatively low yield, we conclude that a single 2-phase investigation (screening followed by clinical examination) provides accurate information for most population-based prevalence studies of dementia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Cross-Sectional Studies
  • Dementia / diagnosis*
  • Dementia / epidemiology*
  • Diagnostic Errors*
  • Female
  • Follow-Up Studies
  • Humans
  • Longitudinal Studies
  • Male
  • Neurologic Examination
  • Neuropsychological Tests
  • Prevalence
  • Sensitivity and Specificity
  • Spain / epidemiology
  • Surveys and Questionnaires
  • Time Factors