P4-124 IS DEMENTIA UNDERDIAGNOSED? ANATIONWIDE POPULATION-BASED STUDYUSING NATIONAL REGISTERS

Kieu T. T. Phung1, Berit L. Waltoft2, Lars V. Kessing1,Preben B. Mortensen2, Gunhild Waldemar1, 1Copenhagen UniversityHospital Rigshospitalet, Copenhagen, Denmark; 2National Center forRegister-Bases Research, Aarhus, Denmark. Contact e-mail:kieu.phung@rh.regionh.dk

Background: Today, dementia is believed to be significantly underdi-agnosed and undertreated. To evaluate the extent to which dementia hadbeen diagnosed in the secondary health-care sector, we conducted anationwide longitudinal study of incidence and prevalence of dementiaover 34 years using the Danish national registers. Methods: Linking theDanish Civil Registration System with the Danish hospital registers, thewhole Danish population was followed from their 40th birthday orJanuary 1, 1970, whichever came later, to date of dementia diagnosesregistered for the first time in the hospital registers both as in- andoutpatients, date of emigration, date of death, or December 31, 2004,whichever came first. Age-, gender-, and period-specific incidence ratesand prevalence of dementia were calculated and compared to estimatesfrom large community-based cohort studies in Europe. Results: Thestudy population consisted of 4,723,838 persons with 81,090,583 per-son-years of follow-up. From 1970 to 2004, 154,152 dementia caseswere identified. The average age at diagnosis was 78.5 (SD 9.8).Following the global phenomenon, incidence of dementia was very lowbefore the age of 65 but started to double thereafter for every 5-yearincrement in age. Taking the 2003 as the year with the most completeregistration, the age-standardized incidence rate for the populationolder than 65 in 2003 was 10.46 per 1000 person-years. Compared tothe age-standardized incidence rate of 15.79 per 1000 person-yearsfrom large European community-based cohort studies, a standardizedincidence rate ratio of 0.66 was obtained. Conclusions: A surprisinglyhigh number of the expected dementia cases in the population, abouttwo-thirds of them, were diagnosed in the secondary health-care sector.This finding challenges the belief that dementia is significantly under-diagnosed. Additionally, being able to capture two-thirds of the nation-wide dementia cases, the Danish hospital registers prove to be valuableand valid resources for studies in dementia epidemiology.

P4-125 HYSTERECTOMY IN PREMENOPAUSAL WOMENIS ASSOCIATED WITH INCREASED RISK FOREARLY ONSET DEMENTIA: A NATIONWIDEREGISTER-BASED STUDY

Kieu T. T. Phung1, Thomas M. Laursen2, Annette Settnes3,Lars V. Kessing1, Preben B. Mortensen2, Gunhild Waldemar1,1Copenhagen University Hospital Rigshospitalet, Copenhagen,Denmark; 2National Center for Register-Bases Research, Aarhus,Denmark; 3Hillerød University Hospital, Copenhagen, Denmark.Contact e-mail: kieu.phung@rh.regionh.dk

Background: Globally, hysterectomy is a very common surgical pro-cedure among women and approximately 80% of hysterectomies aredone on benign indications to increase quality of life. Recent studieshave indicated that hysterectomy could be associated with increasedrisk for dementia. To determine whether hysterectomy is a risk factorfor dementia, we conducted a nationwide historical cohort study usingthe Danish national registers. Methods: From the Danish Civil Regis-tration System, a cohort was selected consisting of all female Danishresidents born before 1966 (at least 40 years old in 2006). By linkingdata with the Danish hospital registers, this cohort was followed fromJanuary 1st, 1977 or the age of 40, whichever came later, until date ofdementia diagnosis registered for the first time in the hospital registers,

date of death, date of immigration, or December 31st, 2006, whichevercame first. Women diagnosed with dementia before 1977 and womenwho have undergone oophorectomies were excluded. The relative risksfor developing dementia were stratified by age at hysterectomies (20-30, 30-40, 40-45, 45-49, 50-55, 55-59, 60-69, 70-79, 80-89, 90 andabove). All the relative risks were controlled for age at dementiadiagnosis (one-year strata) and calendar year (one-year strata) at de-mentia diagnosis. Results: The cohort consisted of 2,313,388 femaleswith 37,186,116 person-years of follow-up. From 1977 to 2006, therewere 95,257 dementia cases and 1,309 hysterectomies. Compared toreferent women of the same age group who had never had hysterecto-mies, women who had undergone hysterectomies had an increased riskof dementia, but only with early-onset dementia (dementia onset be-tween 40-50 years old) (1.37, CI: 1.06, 1.77). Within this group ofearly-onset dementia, the younger was the age at hysterectomy, thegreater was the risk. Conclusions: Premenopausal hysterectomy wasassociated with early-onset dementia, regardless of ovarian status. Theeffect of hysterectomy on early-onset dementia was age-dependent.Further studies are needed to confirm this association and to clarify themechanisms underlying this association. As hysterectomy is such acommon operation among women worldwide, this is an area where riskmodification may have a great public health impact.

P4-126 METABOLIC SYNDROME, SUCCESSFUL ANDPATHOLOGICAL NEUROAGING IN A STROKE-FREE ELDERLY POPULATION

Matheus Roriz-Cruz1, Idiane Rosset1, Teiji Sakagami2,Jarbas S. Roriz-Filho3, Eliane P. Morais1, Rosalina A. P. Rodrigues3,Kozo Matsubayashi2, 1Federal University of Rio Grande do Sul State,Brazil, Porto Alegre, Brazil; 2Kyoto University, Kyoto, Japan;3University of Sao Paulo, Sao Paulo, Brazil. Contact e-mail:matheusroriz@hotmail.com

Background: Large part of the age-related neurofunctional decline isassociated with stroke and cerebral microangiopathy. Metabolic Syn-drome (Met.S) is a risk factor for both of these cerebrovascular disor-ders. It is unknown if Met.S is associated with neurofunctional declinein a stroke-free population. Methods: We evaluated 422 healthy com-munity-dwelling elderly (� 60) in Brazil. Mini-Mental State Examina-tion (MMSE), Geriatric Depression Scale (GDS), ‘Up&Go’ and Func-tional Reach tests, Executive Function and Activities of Daily Livingwere assessed. All reported values have P � 0.05. Results: Met.S waspresent in 39.3% of the subjects. Neurofunctional scores were signifi-cantly lower in the Met.S than in the control group (F: 2.7-5.9). Agealone explained 47% of all MMSE variance in the Met.S group, but just12.8% among controls (P � 0.001 for difference). Age accounted for18.7% of the variance on GDS in the Met.S group, whereas GDS scorewas not related to age in the control group. Analogously, the controlgroup tended to have a more homogeneous score through all ages forevery variable, whereas the Met.S group tended to have lower perfor-mances with increasing age (P � 0.05 for all differences). Adjusting forindividual Met.S components reduced the power of the correlationsbetween the number of Met.S components and evaluated neurofunc-tional scores (from R: 0.130-0.227 to R: 0.101-0.183), but did noteliminate their statistical significances, evidencing a synergism. Thestrong inverse correlation between the MMSE and GDS scales wasrestricted to the Met.S group (B: 0.38; P � 0.001). Conclusions: Met.Swas independently associated with lower cognitive, executive, neuro-motor and functional scores, and with more depressive symptoms.Association between cognitive dysfunction and depressive symptomswere explained in terms of Met.S-associated cerebrovascular risk.Met.S might be a major determinant of ‘successful’ or ‘pathological’neuroaging in western societies.

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