Abstracts

Ncurocpidemiology 1992; 11:100-110

Annual Meeting of the World Federation of Neurology Research Group on Neuroepidemiology

1

Chronic Symmetric Polyneuropathy in the Elderly: A Field Screening Investigation in Two Italian Communities E. Beghi For the Italian General Practitioner Study Group (1GPSG), Istituto di Ricerche Farmacologiche ‘Mario Negri’, Milan, Italy The prevalence of chronic symmetric polyneurop­ athy (CSP) in the community is virtually unknown. Clinically based studies show that CSP is a common complication of several clinical conditions and envi­ ronmental risk factors. This is even more important in elderly subjects who are at a higher risk of developing the clinical disorders most likely to provoke CSP. For these reasons, a field survey was started in two sepa­ rate geographic areas of Italy (Arcisate and San Gio­ vanni Rotondo) where previous experience with epi­ demiologic investigations had found interested collab­ orators with good scientific background. Two groups of general practitioners (GP) and their affiliates (total population, 48,378) served as monitors and targets, respectively, for a screening investigation of CSP con­ ducted during outpatient visits. A seven-symptom questionnaire, previously tested for validity and interrater agreement, was adopted by the GP to ascertain patients aged 55 years and older with symptoms attributable to CSP among those who were asking for ambulatory medical consultation. Patients who gave two or more positive answers to the screening ques­

tions were then given a neurological exam by a trained neurologist. Based on the results of the neurological exam, CSP was diagnosed through a bilateral impair­ ment of the nerve function (one or more modalities) in the upper and/or lower extremities with symmetri­ cal and predominantly distal distribution. A pilot study was performed on 168 individuals (92 M; 76 F) in one of the study areas (Arcisate). Twenty-seven per­ cent of the cases had one or more pathologic condi­ tions causing CSP (mostly diabetes), 15% were under chronic drug treatment, and 4% report a history of occupational exposure to environmental toxins. For­ ty-three (26%) subjects complained of 2+ symptoms of polyneuropathy and clinical findings compatible with CSP were present in 17. CSP was most common in patients with uremia, diabetes, and exposure to environmental toxins (including alcohol).

2

Twinning Rates and Cerebral Palsy J.M. Scheller, K.B. Nelson Neuroepidemiology Branch, NINDS, NIH, Bethesda, Md., USA Objective: To examine the impact of twinning rates in the US on the rates of cerebral palsy (CP). Background: Twins have a relatively high rate of neurologic morbidity, contributing an excess of cases of CP and mental retardation relative to their fre-

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May 4, 1992 San Diego, Calif., USA

quency in the general population. One reason for this higher rate of morbidity is the twins’ high rate of pre­ mature birth. In a recent population-based prevalence study of CP in California, twins, 2 % of survivors to age 3, contributed 10% of all CP cases. Methods: Figures for total live births, plural births, and birth weights were reviewed for the years 1960— 1988 using data from the 'Vital Statistics of the U nited States’. Until 1985, figures were based on a 50% sam­ ple of birth certificates from all states. After 1985. data was based on 100% of the certificates from all states. Results: In 4.25 million live births in 1960, the twinning rate was 2%. The rate declined from that point through the early 1970s to bottom at 1.8% in 1971. The twinning rate has increased steadily in the late 1970s and 1980s to reach 2.2% in 1988. 27 thou­ sand more twins were born in 1988 than in 1974. Between 1960 and 1988, the percentage of twin live births, who were less than 1.500g, remained between 9.8 and 10.9%. The mortality rate in this group decreased by more than 50% over that time. Conclusion: As the twinning rate increases and as their risk of death decreases, twins will contribute in greater numbers to the overall CP prevalence.

scans and 17 (68%) boxers with abnormal CT scans self-reported a previous TKO/KO. respectively. This was compared to only 89 (37%) of the 238 boxers with normal CT scans (p < 0.01). The presence of a cavum septum pellucidum (CSP) was noted in 45 boxers (13%). Thirty-nine were small and 6 were considered large. Brain atrophy was more frequently noted in those boxers with a large CSP compared to those with small or no CSP (p < 0.5). Boxers with abnormal or boderline CT scans that experienced a TKO/KO were slightly older (mean = 28 years) than boxers with a nor­ mal CT scan and a self-reported history of TKO/KO (mean = 26 years: p < 0.5). Since our data were crosssectional, a causal relationship cannot be established.

4

Population Attrition and Use of Surrogate Respondents in the Sicilian IMeuroepidemiologic Study F. Meneghinia, F. Grigolettob. D. W. Andersonc, W.A. Rocca d. L. Morgan le e, A. Reggiof, G. Savettierit, R. DiPerric

Computed Tomography in 338 Active Professional Boxers B. Jordan, C. Jalire, W.A. Hauser, R. Zimmerman, M. Zarrelli, E. Lipsitz, V. Johnson, R. Warren, P. Tsairis, F. Folk Cornell University Medical Center, Ithaca, N.Y.; Columbia University, College of Physicians and Surgeons, New York, N.Y., and New York State Athletic Commission, New York, N.Y.. USA Computed tomography (CT) was conducted on 338 active professional boxers, either licenced or ap­ plying for a license to box in New York State. CT cans were abnormal in 25 boxers (7%). The most common abnormality was brain atrophy (22 cases). Focal hypodense lesions consistent with posttraumatic encephalomalacia were noted in only 3 boxers. Boxers with abnormal CT scans did not differ from those boxers with borderline or normal CT scans with regard to age, win-loss record, number of bouts, or history of an abnormal electroencephalogram (EEG). A prior his­ tory of TKO or KO was self-reported by 143 (42%) boxers. Thirty-seven (49%) boxers with borderline CT

We addressed two major methodological issues in door-to-door, two-phase prevalence surveys of neuro­ logical diseases: (1) impact of nonrespondent, and (2) use of surrogate respondents. The SNES Project, a survey conducted in Sicily in 1987, provided data for the analyses. The screening consisted of a symptom questionnaire and several simple tasks; whenever the subject was unavailable, information was obtained by interviewing a surrogate respondent. For the present study, SNES data were restricted to subjects over 12 years of age (n = 21,658). (1) In the screening phase nonrespondents were classified as refusals, unreachables, and death. Refusals (n = 855) were most com­ mon among subjects aged 60-69 years. Those refusals

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•’ Department of Biostatistics and Epidemiology, Fidia Research Laboratories, Abano Terme, Italy; bDepartment ofStatistical Science, University of Padua, Italy; c Biometry and Field Studies Branch, National Institute of Neurological Disorders and Stroke, Bethesda, Md., USA;dIta!ian Multicentre Study on Dementia, SMID Centre, Florence, Italy; 'Department of Neurology, University of Messina, Italy; d ep artm en t of Neurology, University of Catania, Italy; *Department of Neurology, University of Palermo, Italy

screened indirectly (n = 59) were relatively less edu­ cated. Of the 1,606 eligible subjects who could not be reached, 39% were screened indirectly. Indirect screening was used more frequently for young edu­ cated. and employed men. Death was attributed to 108 subjects (mainly elderly men). Indirect screening infor­ mation suggested that both refusals and unreachablcs tended to be healthier than the general population. By contrast, eligible subjects who died had a higher preva­ lence of neurological diseases (e.g.. 15% had a stroke). In phase 2. we obtained information on 85% of the 123 subjects who could not be clinically examined. With­ out this effort, the impact of phase 2 nonresponse on prevalence estimates would have been noticeable. (2) The screening was administered to surrogate re­ spondents for 958 subjects. More women than men served as surrogates. The ability to answer, as mea­ sured by the do not know rate, varied with the relation­ ship of the surrogate to the index subject and with the nature of the question. Also, surrogate women per­ formed slightly better than surrogate men. Our results may guide identification of subjects more difficult to reach, and indicate the need to minimize the adverse impact of nonresponse on prevalence. In addition, some suggestions to identify the most adequate surro­ gate respondent are given.

5

Sex Ratio of Multiple Sclerosis (MS) Patients' Offspring Compared to Ageand Sex-Matched Controls

The male to female ratios of patients’ and controls’ off­ spring did not differ (1.2 vs. 1.5, respectively). The fol­ lowing table summarizes subgroup comparisons made, none of which showed a significant difference: R a t i o o f m a le t o f e m a le b i r t h s M S fa th e rs B e fo re o n s e t age A fte r o n s e t age

S }« ol } 10 M S m o th e rs

B e fo re o n s e t age A fte r o n s e t ag e

C o n tro l fa th e rs

\i } 12

C o n tro l m o th e r s

M

!«

Male to female ratios of disabled versus nondis­ abled patients’ offspring were also compared but did not differ, either overall (1.1 vs. 1.2) or when male MS patients (1.4 vs. 0.8) and female patients (0.8 vs. 1.3) were considered separately. More of the female MS patients’ children were born before the onset age than female controls’ (63 vs. 47%, p < 0.02), perhaps because patients feared com­ plications related to pregnancy or their disease. Similar numbers of female patients and controls reported mis­ carriages, stillbirths or other pregnancy complications after onset age. Only 10% of patients reported an epi­ sode of MS during a pregnancy following onset, and 18% postpartum. Female patients who gave birth after onset were no more likely than those who did not to become disabled. This study neither confirms an altered sex ratio among MS patients’ offspring, nor suggests that sex ratio variations are associated with disability out­ come.

5. Warren, K.G. Warren University of Alberta, Edmonton, Alta., Canada

102

Abstracts

6

Epidemiology of Internal Carotid Artery Disease: A Population-Based Study Si. Kiechl, F. Oberhollenzer, G. Egger, F. Spogler, J. Willeib The prevalence of asymptomatic carotid artery ath­ erosclerosis was examined in 909 subjects from the Bruneck Heart/Stroke Study. 1,000 men and women, aged 40-80 years (125 in each decade), were randomly selected from the age/sex register of Bruneck. 93.6%

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Relationships have been observed between paren­ tal diseases and alteration in the sex ratios of offspring. Several researchers have compared the sex ratios of male and female MS patients’ offspring, or compared patients’ offspring to births in the general population, with conflicting results. No studies have compared MS patients’ offspring to those of matched controls. At the University of Alberta MS Clinic, 150 MS patients who had consecutive appointments were matched to friends and non-blood relatives on age and sex. There were 103 pairs in which both the patient and the control had had at least 1 live birth (25 male and 78 female pairs). The average number of children among MS patients was 2.3 and among controls 2.2.

participated, 27 patients were excluded because of his­ tory of transient ischemic attack or stroke or missing data. High resolution duplex scanning was used to assess the extent of internal carotid atherosclerosis. No significant disease was found in 273 men (59%) and in 316 women (70%). Moderate and severe carotid artery stenosis (>40% ) was absent in subjects younger than 50 years. The highest prevalence rates of relevant ste­ nosis (>40% ) were detected for men aged 60-69 (13%) and 70-80 (15%), whereas women in the same decades presented with 6 and 9%. The presence and extent of mild internal carotid disease were signifi­ cantly higher in men. For the general population (considering the age/sex distribution in Bruneck, South Tirol), we assessed the following prevalence rates for mild stenosis ( 80%) and occlusion: 25.3, 3.3, 1.2 and 0.5% for men. and 21.5, 2.2, 1.3 and 0.2% for women. The relevance of well-established and suspected cardiovascular risk fac­ tors for carotid artery disease are discussed.

7

Risk of Hemorrhagic Transformation following Thrombolytic Therapy in Experimental Stroke: A Meta-Analysis

boembolic model. Eight papers were excluded from the meta-analysis as they did not meet the following criteria: (1) correct randomization within each experi­ ment (4 papers), and (2) objective assessment of intra­ cranial bleeding (i.e. CT scan or neuropathologic ex­ amination, 4 papers). In the remaining 5 studies, in 7 experiments i.v. t-PA infusion was given (n = 77), in 2 an i.v. t-PA analogue (n = 21) and in 1 intracarotid urokinase (n = 18). Overall, we found an odds ratio (OR) of 2.05 for intracerebral bleeding in the treat­ ment group (95% confidence intervals 1.09-3.85). ORs were also calculated for size of hemorrhagic lesions and for interval between treatment and isch­ emic insult, but the result was not statistically signifi­ cant in either case. In conclusion, although the risk of intracerebral haemorrhage following thrombolytic treatment in ani­ mal stroke models seems increased, a larger number of cases is required to confirm the significance of this finding. Indeed, the exclusion of many papers with incorrect experimental conditions and lack of detailed information prevented subgroup analysis on the type of animal model, hemorrhage size, type of thrombo­ lytic agent given, dosage, interval between ischemic insult and hemorrhagic transformation, and rccanalization. However, we recommend that meta-analysis of experimental studies should be performed for at least two reasons: (1) this approach could be of help to stan­ dardize methodology of these studies, and (2) it would increase the sample size and give statistically signifi­ cant results, thus avoiding further wastage of animal lives.

A. Ciccone, E. Aritzu, L. Candelise Istituto di Ricerche Farmacologiche 'Mario Negri’, Istituto di Clinica Neurologica, Universita degli Studi, Milano, Italy

8

Cardiac Arrhythmias: A Predictor of Recurrent Stroke and Death after Initial Stroke N. Pickeringa. M. Alter3. S-M. Lai3, R. Haberman3, E. SobeP\ G. Fridaya a Medical College of Pennsylvania, Philadelphia, Pa., and bUnivcrsity of Southern California, Los Angeles, Calif., USA We investigated the frequency of recurrent stroke and death in 664 patients enrolled within 2 weeks of initial stroke. The study population consisted of 344 men and 320 women with a mean age of 72 years. Of

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Intracranial hemorrhage is the most feared compli­ cation in ischemic stroke treated with thrombolytic agents. Data in man are unclear and most available information comes from experimental studies. To assess the risk of hemorrhagic transformations following thrombolytic therapy in animal models of focal ischemia, we set out to review the available stud­ ies using a quantitative approach. We performed a search of the Cumulative Index Medicus and of the bibliographies of all relevant papers, and identified 13 papers which included 528 animals. Two hundred had intracranial bleeding complications (43% allocated to the thrombolytic group and 34% to the control group). All the studies used rabbit embolic stroke models except 2 of a baboon model with temporary occlusion of the middle cerebral artery and 1 of a dog throm­

these, 590 patients were followed until stroke recur­ rence or death. Only arrhythmias recorded at enroll­ ment with a standard 12-lead ECG and rhythm strip were analyzed and used to predict clinical outcome. The diagnosis of stroke was made utilizing clinical assessment and CAT scans. 106 (16 %) had atrial fibril­ lation (AF) and 68 (10%) had ventricular premature contractions (VPC). During follow-up, 66 patients (11 %) had a second stroke and 137 (23%) died of other causes. AF was significantly increased with second stroke (p = 0.01) and death (p = 0.04). but only in those over the age of 75 at enrollment. VPC were signifi­ cantly associated with death (p < 0.001) in those less than 65 years of age. VPC were not associated with second stroke (p = 0.06). Using multivariate analysis, the associations of these arrhythmias and recurrent stroke or death were independent of gender, myocar­ dial infarction and hypertension. The detection of VPC and AF within 2 weeks of initial stroke may jus­ tify intensive cardiac evaluation and closer monitoring of the cardiac status as these arrhythmias appear to portend a poorer prognosis after stroke.

a reduced risk of subarachnoid hemorrhage (OR = 0.60. 95% Cl 0.4-1.0). Binge drinking, defined as con­ suming 5 or more drinks during a 24-hour period, was more common among SAH cases (OR = 2.7, 95% Cl 1.3-5.7). A dose response with increasing frequency of binge drinking was observed (p < 0.001), with those binging one or more times per week having a smokingadjusted odds ratio of 3.8 (95% Cl 1.3-11.2). After controlling for the time since the last cigarette, no clear pattern emerged for the relation between the time since the last drink and the risk of subarachnoid hem­ orrhage. Potential confounders other than cigarette smoking (e.g. hypertensive status, use of stimulated drugs, race, education) had little effect on relative risk estimates. The effect of alcohol on risk of subarach­ noid hemorrhage could be mediated through increases in blood pressure or impaired coagulation.

10

Hypertension in the Parsis of Bombay, India N.E. Bharuchai h. A.E. Bharacha*•c, D. W. Andersond. E.P. Bharuchaa b

Alcohol Consumption and Subarachnoid Hemorrhage: A Population-Based Case-Control Study W.T. Longsiretli Jr, L.M. Nelson, T.D. Koepsell. G. van Belle University of Washington, Seattle, Wash., USA A population-based case-control study of subarach­ noid hemorrhage (SAH) was conducted in King Coun­ ty. Wash., with cases being identified by physicians and hospital discharge diagnoses. Over a 2-year study period, 149 SAH cases were enrolled in the study. Ran­ dom-digit telephone dialing was used to identify two age- and gender-matched controls for each case. Struc­ tured interviews were conducted with all SAH cases who were cognitively intact, all controls, and proxy respondents for all cases and controls. Analyses in­ volved conditional logistic regression taking into ac­ count matching on age, gender and respondent type. For alcohol consumption, using non-drinkers as the reference group, heavy drinkers (> 2 drinks/day) were at increased risk for subarachnoid hemorrhage (OR = 2.2,95 % Cl 0.9-5.1, having adjusted for current and past smoking). Light drinkers (< 1 drink/day) had

104

Abstracts

a Neuroepidemiology Department, Medical Research Centre, Bombay Hospital. Bombay, India; bK.E.M. Hospital and Seth G.S. Medical College, Bombay, India;c Department of Internal Medicine, Mayo Clinic, Rochester, Minn., USA; d Biometry and Field Studies Branch, National Institute of Neurological Disorders and Stroke, Bcthesda, Md„ USA A community-based survey of stroke among the Parsis of Bombay. India, has revealed a prevalence of 842.3 cases/100.000 inhabitants. A case-control study in that population showed hypertension to be a potent risk factor. We have subsequently surveyed a 1:4 ran­ dom sample of the adult population (> 2 0 years) for hypertension (BP > 140 mm Hg systolic or > 90 mm Hg diastolic). Within the sample, the frequency of hypertension was found to be 27.6% (793/2,877). The frequency in men was lower than that in women; 24.8% (333/1,343) versus 30.0% (460/1,534). Isolated systolic hypertension (systolic > 160 mm Hg and dia­ stolic < 90 mm Hg) was present in 6.3 % ( 180/2,877) of sample members. Other statistics of interest include the following: 78.9% (2,269/2,877) of sample members had ever had their blood pressure measured; a history

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9

of diabetes was obtained in 17.4% (138/793) of hyper­ tensives and in 5.9% (122/2,084) of non-hyperten­ sives; a history of ischemic heart disease was obtained in 14.2% (113/793) of hypertensives and in 6.0% (126/2,084) of non-hypertensives; a history of focal neurological deficit was obtained in 4.4% (35/793) of hypertensives and in 1.0% (20/2,084) of non-hyperten­ sives. To our knowledge, this is the first time in a developing country that a prevalence study, a casecontrol study, and a risk factor analysis of a neurologi­ cal condition have been accomplished as a sequence of steps within the same community. The next step is an intervention study.

to 100% of the follow-ups to determine the effect of quality of control. If diastolic blood pressure was under 95 mm Hg on at least 75% of follow-ups, the stroke recurrence frequency was significantly reduced (p < 0.0005). Stroke recurrence frequency also ap­ peared to be linearly increased at the 6% significance level among those whose blood pressure was controlled on less than 75 % of the follow-ups. Similar results were not obtained for systolic measurements using 160 mm Hg as the criterion for control of blood pressure. Our study offers proof for the importance of diastolic blood pressure control in the prevention of recurrent stroke in hypertensives provided such control is present at least 75% of the time.

11 12

M. Altera, G. Fridaya, E. Sobelb, II. Saranadasaa, J. Mauia, E. Gracely3

Intervention Trial of Stroke Risk Factors in 7 Cities of the People's Republic of China. II. Preliminary Results

“Medical College of Pennsylvania, Philadelphia, Pa.; bUniversity of Southern California School of Medicine, Los Angeles, Calif., USA

China Neuroepidemiology Research Group: X.M. Cheng. S.C. Li, G.X. Jiang, O S. Dai, X.F. Lu, M.L. Rao, J.R. Song, F.Z. Su

Hypertension is a well-recognized risk factor in ini­ tial stroke but its effect on stroke recurrence has not been well studied. Moreover, it is unclear whether con­ trol of hypertension decreases risk of recurrent stroke. We examined risk of recurrent stroke among 661 patients with an initial stroke of whom 93% were enrolled within 2 weeks of onset. The diagnosis was verified as a first-ever stroke both clinically and by CT using standardized criteria similar to those of the Stroke Data Bank. The presence of hypertension was determined by patient interview, chart review, exami­ nation of medication and blood pressure measurement at rest. A total of 60% of the cohort was hypertensive at enrollment. The patients were re-evaluated at home about every 6 months. If any history of possible recur­ rent stroke was obtained or the patient showed new neurologic deficits, the patient was re-examined by the study neurologist to determine whether a new stroke had occurred. 59 (15%) of the hypertensives and 21 (8%) of the non-hypertensives had a recurrent stroke after an average follow-up of 24 months (range < 1 month to 48 months; p < 0.006). Stroke recurrence frequency was determined for hypertensive individu­ als whose diastolic blood pressure, when measured, was under 95 mm Hg for varying proportions from 50

Beijing Neurosurgical Institute, Beijing, Republic of China A program on the intervention of stroke risk factors and multicenter monitoring of trends in cerebrovascu­ lar disease has been carried out in 7 cities of China as a primary prevention study to test the effect of multifac­ tor intervention on the incidence and mortality of stroke. The study was designed to lower high blood pressure and enhance self-health care of the test popu­ lation through intensive health education. Over a 4year follow-up, according to the design of the project (described in a separate paper), the results of the inci­ dence and mortality study between community A and B, cohort population CA and CB, subgroups CAa and CBa are as follows: (l) the incidence and mortality rates declined year by year for community A, the aver­ age incidence declined by 20% per year, the average mortality declined by 17% per year, in contrast, there was no obvious change in community B; (2) compari­ son between CA and CB, the person-year incidence was 309 for CA and 441 for CB, the person-year mor­ tality was 122 for CA and 184 for CB, the differences between CA and CB were statistically significant (p < 0.01 and 0.05 < 0.1). The preliminary' results were encouraging. How­ ever. the investigation should be extended. The differ­ ences in incidence and mortality between CAa and CAb. CBa and CBb will also be discussed.

tests were the Boston Naming Test, the Similarities Test, and Drawing Tasks. The three identified sub­ groups have differing degrees of dementia severity and differ on some ADL activities. Future work is required to determine whether the subgroups differ on clinical and neuropathologic variables.

15

Education in Cross-Cultural Dementia Screening: Applications to a New Instrument

multivariate logistic regression using two outcomes: CASI, dichotomized at 86 from the overall ROC anal­ ysis, and diagnostic classification. The odds ratios for age and gender were not significantly different from 1.0 in both analyses. When comparing 12 years of edu­ cation with 13+ years, a significant association was found only for the CASI analysis (adjusted OR = 2.37. 95% Cl 1.04-5.42) but not for the analysis of case sta­ tus (adjusted OR = 1.44, 95% Cl 0.64-3.27). When comparing 0-11 years of education with 13+ years, a statistically significant risk was present in both analy­ ses (OR = 7.84, 95% Cl 2.72-22.58 for CASI analysis and OR = 4.85. 95% Cl 1.83-12.82 for case status analysis). We conclude that education is an important factor in cognitive testing, and may also be so in diag­ nostic classification in those with less than high school education.

A.B. Gravesa, E.L. Tengb. E.B. Larsonc, L.R. Whited

In order to analyze the performance characteristics of a new dementia screening instrument designed for use in cross-cultural epidemiologic studies, we per­ formed pilot testing in 57 probable AD cases and 88 controls who had been followed for a year or longer as part of the Alzheimer’s Disease Patient Registry in Seattle, Wash. Cases (65% female) were on the average 78.9 years old with 12.3 years of education. Controls (63% female) were on the average 77.6 years old with 13.8 years of education. The Cognitive Abilities Screening Instrument (CASI) [Teng EL, Hasegawa K, Homma A, Imai Y, Larson EB, Sasaki H. White LR: Cognitive testing in crosscultural epidemiological studies of dementia: The Cognitive Abilities Screening Instrument, in press] merges the Mini-Mental State Examination (MMSE) with the Hasegawa Dementia Scale for the Aged, and has a total score of 100. An optimal cut-off score of 86 (sensitivity = 96.5, specific­ ity = 92.0) was computed from construction of a receiver-operator curve (ROC). Using three educa­ tional levels (13+, 12 and 0-11 years), optimal stra­ tum-specific cut scores were 89 (sensitivity/specificity = 100/92.5), 84 (sensitivity/specificity = 100/92) and 80 (sensitivity/specificity = 94/100), respectively. Al­ though it is well known that education is highly associ­ ated with cognitive test scores, it is more controversial whether education (or related variables) is a risk factor for Alzheimer diagnosis. Therefore, we conducted

16

Incidence of Dementia in Gironde (France): Results of the Paquid Program J.F. Darligues, D. Commenges. P. Barberger-Gateau, L. Letenneur, H. Jacqmin, L. Dequae Unité INSERM 330, Université de Bordeaux II, Bordeaux, France The Paquid Research Program was undertaken in 1988 to study prospectively a representative random sample of 4,134 people aged 65 and older living at home and in institutions in the community of Gironde and Dordogne, two areas of south-western France. During the follow-up, people living in Gironde were seen at 1 year and will then be seen every 2 years with a 2-stage design study. The first stage consisted of a psy­ chometric screening made by psychologists on the basis of the DSM-IIIR criteria for dementia. In the sec­ ond stage, subjects who met the DSM-IIIR criteria for dementia were seen by a senior neurologist who filled in the NINCDS-ADRDA criteria for Alzheimer’s Dis­ ease (AD) and the Hachinski score the etiology of dementia. After 1 year of follow-up, the estimated numbers of new cases per 100,000 person-years were 599 for AD, 183 for multi-infarct dementia and 307 for other dementia. The results of the 3rd year of follow-up will be presented and discussed.

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a Battelle and University of Washington. Seattle, Wash.; bUniversity of Southern California, Los Angeles, Calif.; 'University of Washington, Seattle. Wash., and dNational Institute on Aging, Bethesda, Md., USA

17

18

Issues Related to the Selection of Controls when Exposure Is Related to Diagnosis

Validation of the Mini-Mental State Examination (MMSE) as a Screening Instrument for Dementia in an Italian Population

Case Western Reserve University, Cleveland, Ohio. USA Demented patients are diagnosed with Alzheimer’s Disease (AD) only when conditions that may lead to other dementias are not present. Among them are alco­ holism, severe emphysema and certain cardiovascular diseases. Cigarette smoking, and exposure postulated as having a protective effect for the development of AD, is positively associated with these conditions [Graves AB, ct al: Alcohol and tobacco consumption as risk factors for Alzheimer’s disease: A collaborative re-analysis of case-control studies. Int J Epidemiol 1991;20(suppl):48-57]. Thus, those patients diagnosed with probable AD may have a different pattern of smoking from the gen­ eral population and also from hospitalized patients, a typical source of controls in case-control studies. Par­ ticular care must be exercised, then, in the selection of controls in case-control studies that seek to further explore the relationship of AD and cigarette smoking. Since some of the reasons for excluding individuals from a diagnosis of AD may be related to smoking, it is necessary to consider whether specific restrictions af­ fect potential cases and controls evenly. For example, age matching seems quite reasonable, yet may be a source of some bias if it is indeed true that cigarette smoking both shortens some lives and delays the onset of AD during some individuals’ life times. Clearly, if no restrictions apply to controls, there will be more smokers among controls; however, if all restrictions that are applied to cases are applied to controls, the proportion exposed may be inappropriately small, thus weakening power. Some general guidelines will be offered: issues of generalizability will also be addressed.

108

Abstracts

F. Cavarzerana. W.A. Roccah, P. Maionec, C. Valentec, A. Lippib, P. Taitic, A. Bavazzanoc, L. Amaditcci6 a Department of Biostatistics and Epidemiology, Fidia Research Laboratories, Abano Terme, Italy; bItalian Multicentre Study on Dementia, SMID Centre, Florence, Italy; cUnita Operativa Geriatria, Ospedale di Prato, Italy;d Department of Neurology and Psychiatry, University of Florence, Italy We investigated the validity of the MMSE as a screening instrument for dementia in an Italian popu­ lation. A probability sample of 158 subjects over the age of 59 years was drawn from the list of residents kept by the registry' office of Carmignano municipality (Florence Province, Italy). The sample was stratified by age and sex, with overrepresentation of the age class 80-89 years. The MMSE was administered by one of two geriatricians at home or at the institution of resi­ dence. All subjects also underwent a standardized diagnostic protocol for dementia according to DSMIII criteria (standard for comparison). Diagnoses of dementia were made by a geriatrician and were re­ viewed by an experienced neurologist. Screening and examination visits were conducted between Septem­ ber 1988 and February 1990. Ten of the 158 subjects were found to be affected by dementia. Scores at the MMSE were compared to the corresponding clinical diagnosis to calculate sensitivity and specificity at dif­ ferent cut-off levels. A score of 17 or less showed the best combination of sensitivity (100.0%) and specific­ ity (97.3 %). The traditional screening level of 23 or less yielded a sensitivity of 100.0% and a specificity of 84.5%. At all screening levels, the specificity was higher for younger and for more educated subjects. Specificity was not different for men and women. Results of our study suggest that the MMSE may be used to screen for dementia in the Italian population. The traditional cut-off score of 23 or less may be con­ venient: it increases the likelihood of detecting mild or recent onset cases of dementia without a major loss in specificity.

Annual Meeting of the World Federation of Neurology

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S.M. Debanne, D. Y. Rowland, A. Sclmell, P. Hederá. E. Koss. A. Lerner, K. Smyth, P.J. Whitehouse. R. Friedkmd

An Update on the Epidemiologic Status of ALS/PDC on Guam John C. Steele, David B. Williams, Ulla-Katrina Craig, Kwang-Ming Chen, Stephen C. Waring, Leonard T. Kurland Guam Research Station and Mayo Clinic, Rochester, Minn., USA To update the epidemiology of amyotrophic later­ al sclerosis and parkinsonism-dementia complex (ALS/PDC) on Guam, community surveys were com­ pleted between March 1990 and February 1991. As part of an ongoing epidemiologic effort, new patients with ALS or PDC have been identified by intensive village surveys on Guam in recent years, and the results compared with those of surveys nearly 40 years ago. We found a relatively high prevalence of ALS and PDC in Yigo, a village in the northern part of Guam; a high prevalence of PDC and Marianas dementia on the island of Rota; and no definite cases of ALS or PDC in Tinian - suggesting that the distribution of these diseases had not changed appreciably in four decades. The current prevalence case registry identi­ fied 47 Chamorro residents with definite and 30 with suspected ALS/PDC, and 22 with dementia alone. Olfactory studies reveal that odor identification is seri­ ously impaired in early PDC. A unique retinopathy has been discovered on Guam and is occurring in about 15% of the adult Chamorro population; among ALS/PDC patients, the rate approaches 50%. The prevalence of ALS alone is decreasing on Guam and Rota; the age at onset of both ALS and PDC is increas­ ing, and PDC prevalence remains high, with the pre­ dominant manifestation of dementia, especially in older women.

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Rural Residence, Occupation, Food Habits, and Parkinson's Disease B. V. Manyam, J.A. Colliver, S.B. Manyam Southern Illinois University School of Medicine, Springfield, 111., USA With the hypothesis that the environment may contribute to the etiology of Parkinson’s disease, we evaluated the impact of rural residence, occupation,

and life-time food habits in patients with established Parkinson’s disease. The patients’ spouses were uti­ lized as controls. Data were collected through a ques­ tionnaire mailed to 169 pairs (patients and controls) with a return of 154 pairs, giving a 9 1% rate of return. Of these, 32 pairs were excluded because one of the spouses was not alive, 20 pairs had incomplete an­ swers, with a final eligible number of 102 patients with Parkinson’s disease and their spouses as controls suit­ able for a case-control study. The mean age of the patients was 66 ± 10 years, and that of the unaffected spouses, 65 ± 10 years, and their difference was not statistically significant. Current and previous occupa­ tion, residence from the time of birth, and food habits from the time of birth until the current study were evaluated for differences between patients and spouses. The results showed no significant effect of residence, occupation, or dietary habits between the patients and normal control spouses. The data sug­ gested that life-time dietary habits, occupation, and residence have neither a protective effect nor risk asso­ ciated with onset of Parkinson’s disease.

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Epidemiological Studies of Parkinsonism at a Movement Disorder Clinic A.H. Rajput. R.J. Uitty, M. Ho, K. Offord, P. Basran, Alex Rajput University of Saskatchewan. Saskatoon, Sask., Canada, and Mayo Clinic, Rochester, Minn., USA Considerable ‘epidemiological’ information is now generated at the institutions which concentrate on movement disorders. Because of the highly specialized expertise and restricted interests, such clinics often attract unusual and difficult patients. The data thus generated may have a case selection bias and the results should be evaluated carefully. We report our experience at the University of Sas­ katchewan where a movement disorder clinic serves as the primary neurological referral centre. During 23 years (1968-1991) a regular clinic with special interest in movement disorders has been held at Royal University Hospital, Saskatoon serving 0.5 million provincial population. The universal health care and drug plan make the neurologists’ services and treatment equally accessible to all residents. This anal­ ysis includes 934 Parkinson syndrome (PS) cases seen

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Abstracts

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Stroke Incidence and Geographic Location in China Collaborative Study Group, General Logistics Department of the PLA, Zhen-xin Zhang,

Bao-Zun Zhang Department of Neurology, PUMC Hospital, Chinese Academy of Medical Sciences, Beijing, China A nation-wide door-to-door survey in 199 districts and counties of 3 municipalities and 27 provinces of China was conducted on the basis of the WHO proto­ col for stroke. Among 5,790,864 screened individuals, 6,355 incidence cases of first completed stroke were observed in 1986. The significantly highest age-adjusted incidence rates (to the Segi’s world population) were generally found in north-western China (488.8 in Tibet and 234.4 in Jiling) and the lowest rates in south­ eastern China (53.2 in Guangdong), although the ma­ jority of the rates did not differ significantly from the overall rate for China (115.6 per 100,000 population). The underlying causes of geographic variations were sought by relating annual age-adjusted stroke incidence rates for both sexes to geographic data, demographic index, climate, and socioeconomic status at the municipality and province levels for the year 1986. The stroke incidence in China was associated with latitude, longitude, average yearly ambient tem­ perature, yearly sunshine time, and the number of beds and physicians per 1,000 population; not associated with topography, yearly precipitation, population den­ sity, percentage of population living in urban areas, the gross value of industrial and agricultural output per person, the number of persons supported by employ­ ment, average yearly income per person, deposit amount per person in the end of the year, or the num­ ber of students in colleges per 1,000 population.

Annual Meeting of the World Federation of Neurology

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between 1968 and 1990. The severity and the type of PS were comparable to that reported in a prevalence study from Finland in 1976. All patients were seen per­ sonally and the diagnosis was pathologically verified in 30% of deaths: 76% of all and 85% of the deceased cases were treated with levodopa (LD) at some time. The survival when measured from the onset date was normal but was significantly reduced when estimated from the first clinic visit. In 35% of cases the initial diagnosis of idiopathic Parkinson's disease (IPD) and in 24% the final IPD diagnosis were incorrect [Rajput et al: Can J Neurol Sci 1991;18:275-278). In the majority, the correct diagnosis of the other PS variants was possible within 5 years after the motor onset. Because the majority of cases was treated with LD the survival difference between ever versus never treated cases could not be assessed, but early versus late initia­ tion of LD was assessed. It did not significantly influence the survival. Survival has improved in cases with onset after 1973 compared to those with prior onset. Our data indicate that some forms of epidemio­ logical studies can be successfully conducted at spe­ cialty clinics, provided that the profile of the cases is similar to that in the general population and there is no major treatment bias.