title: Prevalence of idiopathic normal-pressure hydrocephalus.
abstract: OBJECTIVE
  The aim of this study was to determine the prevalence of idiopathic normal-pressure hydrocephalus (iNPH) in elderly persons in a large population-based sample using radiologic and clinical examinations.
  
  
  METHODS
  We examined representative elderly populations aged 70 years and older that had undergone neuropsychiatric evaluations and CT of the brain between 1986 and 2000 (n = 1,238). Gait was evaluated by clinical examination and history of walking difficulty. Cognitive function was evaluated with the Mini-Mental State Examination and urinary incontinence by self-report. iNPH was diagnosed in concordance with the American-European iNPH guidelines. Exclusion criteria were history of meningitis, severe head trauma, and subarachnoid hemorrhage.
  
  
  RESULTS
  The prevalence of probable iNPH was 0.2% in those aged 70-79 years (n = 2) and 5.9% (n = 24) in those aged 80 years and older, with no difference between men and women. Only 2 of these persons had been treated for iNPH. Hydrocephalic ventricular enlargement, i.e., a CT image consistent with NPH, was found in 56 persons (4.5%). An Evans Index >0.3 was found in 256 (20.7%) and occluded sulci at the high convexity in 67 persons (5.4%). All of these findings were more common in the older age groups.
  
  
  CONCLUSIONS
  Many elderly possess clinical and imaging features of iNPH, especially those older than 80 years. The number of persons with iNPH is probably much higher than the number of persons currently treated.
authors.affiliation: From the Neuropsychiatric Epidemiology Unit, Department of Psychiatry and Neurochemistry (D.J., T.M., I.S.), Hydrocephalus research unit, Department of Clinical Neuroscience and Rehabilitation (K.R., C.W.), Institute of Neuroscience and Physiology, Department of Radiology, Institute of Clinical Sciences (C.J.), Sahlgrenska Academy, University of Gothenburg, Sweden University of Gothenburg, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Jaraj
authors.forename: Katrin
authors.initials: K
authors.lastname: Rabiei
authors.forename: Thomas
authors.initials: T
authors.lastname: Marlow
authors.forename: Christer
authors.initials: C
authors.lastname: Jensen
authors.forename: Ingmar
authors.initials: I
authors.lastname: Skoog
authors.forename: Carsten
authors.initials: C
authors.lastname: Wikkelsø
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D009483:Neuropsychological Tests; D013548:Sweden; D014057:Tomography, X-Ray Computed