Bovine spongiform encephalopathy and Creutzfeldt-Jakob disease: facts and uncertainties underlying the causal link between animal and human diseases

Following an outbreak of bovine spongiform encephalopathy (BSE) in dairy cows in the United Kingdom (UK), 153 definite and probable human cases of new variant Creutzfeldt-Jakob disease (nvCJD) have been reported, almost exclusively in the UK. Although exposure to the BSE agent is the most plausible interpretation for the occurrence of nvCJD, the causal link between the BSE prion and nvCJD is still debated. This review discusses the pros and cons of nvCJD as a separate nosographic entity, the scientific basis for a correlation between BSE and nvCJD, the validity of the current diagnostic criteria for CJD and nvCJD, the contribution of epidemiology to the detection of a causal relation between BSE and nvCJD, and the present and future directions of the epidemiological research on BSE, CJD and nvCJD.

The relapse rate of multiple sclerosis changes during pregnancy: a cohort study

OBJECTIVE

To evaluate the influence of pregnancy and puerperium on the relapse rate of multiple sclerosis (MS).

METHODS

We determined retrospectively the yearly mean relapse rate (MRR) during pregnancies occurring in the course of relapsing-remitting MS. We compared the MRR of pregnancy-time with that of non-pregnancy time by paired t-test. Relative risk (RR) of relapses during the pregnancy-time was also compared with that of non-pregnancy time by chi(2) analysis and 95% confidence intervals.

RESULTS

From a population of 351 women affected by clinically definite MS, only 70 reported pregnancies during their relapsing-remitting phase of MS for a total of 98 pregnancies. Both MRR (P = 0.006) and RR (RR = 0.63, 95% CI = 0.40-0.94) decreased during the three trimesters of pregnancy. RR increased in the first 3 months of puerperium, although this was not statistically significant (RR = 1.36, 95% CI = 0.79-2.20).

CONCLUSION

Our study confirms that in MS the relapse rate decreases throughout pregnancy and increases during puerperium. This suggests a complex interplay between hormonal and immune factors.

Risk of Parkinson disease in women: Effect of reproductive characteristics

OBJECTIVE

To investigate the association between some fertile life characteristics and Parkinson disease (PD) in women.

METHODS

Women affected by PD and control subjects were matched one to one by age (+/-2 years). One hundred thirty-one women with idiopathic PD and 131 matched control subjects were interviewed. Controls were randomly selected from the resident list of the same municipality of residence of cases. All subjects had a Mini-Mental State Examination score of > or =24. Cumulative length of pregnancies, age at menarche, age and type of menopause, and estrogen use before and after menopause were investigated in cases and controls through a structured questionnaire. Models of matched pair univariate analysis and conditional logistic regression analyses were used to calculate adjusted odds ratio (OR), 95% CI, and two-tailed p values for the investigated variables.

RESULTS

PD was significantly associated with a fertile life length shorter than 36 years (OR 2.07; 95% CI 1.00 to 4.30) and a cumulative length of pregnancies longer than 30 months (OR 2.19; 95% CI 1.22 to 3.91). An inverse association between PD and surgical menopause (adjusted OR 0.30; 95% CI 0.13 to 0.77) was also found.

CONCLUSIONS

An association between factors reducing estrogen stimulation during life and PD was found. These results support the hypothesis that endogenous estrogens play a role in the development of PD.

Tumor diagnosis preceding Parkinson's disease: A case-control study

Lower cancer risk in Parkinson's disease (PD) patients compared to the general population has been reported. However, most of the studies were based on death certificates. We designed a case-control study to estimate the association of tumor preceding PD onset and PD. PD patients were matched by age and gender to PD-free individuals, randomly selected from the municipalities of residence of cases. Occurrence of tumors preceding PD onset was assessed through a structured questionnaire. Neoplasms were categorized as benign, malignant, or of uncertain classification, and endocrine-related or not. Odds ratios (OR) were calculated using conditional logistic regression and adjusted for tumor categories and risk factors. We included 222 PD patients. Frequency of cancer was 6.8% for cases, 12.6% for controls. PD patients had a decreased risk for neoplasms (adjusted OR, 0.4; 95% confidence interval [CI], 0.2-0.7). Risk was reduced only for women (adjusted OR, 0.3; 95% CI, 0.1-0.7). PD patients had a decreased risk both for malignant (adjusted OR, 0.6; 95% CI, 0.1-2.5) and nonmalignant neoplasms (adjusted OR, 0.3; 95% CI, 0.1-0.7). Still, risk was decreased for endocrine-related tumors (adjusted OR, 0.3; 95% CI, 0.1-0.9) and non-endocrine-related tumors (adjusted OR, 0.4; 95% CI, 0.1-0.9). Our study confirms the inverse association between PD and neoplasms reported in previous epidemiologic studies.

Accuracy of Death Certificates for Amyotrophic Lateral Sclerosis Varies Significantly from North to South of Italy: Implications for Mortality Studies

OBJECTIVE

To evaluate the accuracy of death certificates (DCs) for amyotrophic lateral sclerosis (ALS) in different parts of Italy. Studies based on DC diagnosis for ALS have shown a reduced mortality comparing northern with southern Italy. These data are in contrast with results from other surveys on the incidence of ALS performed in Italy and other countries.

METHODS

Archives of neurological clinics from northern (Milano, Monza, Pavia, and Bologna) and southern Italy including islands (Napoli, Sassari, Palermo, and Messina) were searched for patients discharged with a diagnosis of ALS in the period 1970-1995. Subjects affected by definite/probable ALS according to the Scottish Motor Neuron Disease Research Group diagnostic criteria were included. DCs were obtained from the vital statistic bureau. True positive rates (TPRs) and 95% confidence intervals (CIs) for proportions were calculated for northern and southern Italy separately. Multiple logistic regression analysis was performed according to gender, age at onset, age and year of death, and interval between onset and death.

RESULTS

We found 651 patients affected by definite/probable ALS; 573 of them had died by December 31, 1996. DCs were available for 566 subjects (411 from northern Italy and 155 from southern Italy). TPR was 66.7% (95% CI 61.9-71.2) for northern Italy and 51.6% (95% CI 43.5-59.7) for southern Italy (chi(2) = 10.9, p = 0.001). Logistic regression analysis showed an association between a lower accuracy of DCs and the interval between onset of symptoms and death. TPR calculations considering different death periods (1970-1982 and 1983-1996) showed comparable rates of accuracy over time.

CONCLUSIONS

Mortality statistics based on official death records do not accurately reflect interregional mortality for ALS in Italy.

A screening instrument for a Sicilian neuroepidemiological survey in the elderly

We evaluated the sensitivity and specificity of a screening instrument developed for use in a two-phase neuroepidemiological survey in Sicily. The Sicilian Epidemiological Dementia Study (SEDES) project will evaluate the prevalence and incidence of dementia, parkinsonisms and essential tremor in four Sicilian municipalities. It is a two-phase door-to-door survey. To identify subjects with possible neurological disorders, in this study, we developed a screening instrument including a symptoms questionnaire and simple physical tasks for parkinsonisms and essential tremor. The Mini-Mental State Examination (MMSE) was chosen for screening dementia. The symptoms questionnaire and simple tasks developed to identify possible patients with parkinsonism and essential tremor, was tested in a hospital setting. To evaluate sensitivity, we selected 20 patients with essential tremor and 40 with Parkinson's disease (20 with Stages I-II and 20 with Stages III-V) [Neurology 17 (1967) 427]. To evaluate specificity we also selected 20 healthy subjects. The screening instrument was administered in a hospital setting by trained interviewers. Sensitivity of the screening instrument (questionnaire plus simple tasks) was 100% for essential tremor and parkinsonisms regardless of the stage. Specificity of the instrument was 90% (95% CI 66.9-98.2); the predictive positive value was 90.9%, while the negative predictive value was 100%. Even if validity was assessed in a hospital setting, the high sensitivity and specificity obtained suggest that the instrument could be an appropriate screening tool for parkinsonisms and essential tremor in a two-phase neuroepidemiological survey.

Apolipoprotein E genotype does not influence the progression of multiple sclerosis

OBJECTIVE

To investigate the association between apolipoprotein E (APOE) polymorphisms and the progression of MS.

METHODS

We investigated 428 subjects affected by clinically defined MS, with a disease duration of at least three years. We collected data concerning the age at onset of MS, clinical type, disease duration and disability according to the expanded disability status scale (EDSS). We also calculated the progression index (PI) to evaluate disease progression. APOE genotyping and the -491 A/T polymorphism of the APOE promoter were determined.

RESULTS

No association was observed between the APOE epsilon4 allele and clinical characteristics of our study population. We also investigated the -491 A/T APOE promoter polymorphism in 236 MS subjects and did not find any association between the -491 A/T polymorphism and the selected clinical variables.

CONCLUSIONS

In our population the APOE epsilon4 allele and the -491 A/T APOE promoter polymorphism are not associated with a more rapid course of MS.

A whole genome screen for linkage disequilibrium in multiple sclerosis performed in a continental Italian population

We have systematically screened the genome for evidence of linkage disequilibrium (LD) with multiple sclerosis (MS) by typing 6000 microsatellite markers in case-control and family based (AFBAC) cohorts from the Italian population. DNA pooling was used to reduce the genotyping effort involved. Four DNA pools were considered: cases (224 Italian MS patients), controls (231 healthy Italians), index (185 index cases from trio families) and parents (the 370 parents of the patient included in the Index pool), respectively. After refining analysis of the most promising 14 markers to emerge from this screening process, only marker D2S367 retained evidence for association.

A case-control study on cigarette, alcohol, and coffee consumption preceding Parkinson's disease

OBJECTIVE

To investigate the association between cigarette smoking, alcohol drinking, coffee consumption and Parkinson's disease (PD).

METHODS

We selected subjects affected by idiopathic PD, with a Mini-Mental State Examination of > or =24, and controls matched 1 to 1 with cases by age (+/- 2 years) and sex. Controls were randomly selected from the resident list of the same municipality of residence of the cases. We assessed cigarette smoking, alcohol drinking, and coffee consumption preceding the onset of PD or the corresponding time for controls using a structured questionnaire, which also evaluated the duration and dose of exposure. Using conditional logistic regression analysis, we calculated adjusted OR and 95% CI.

RESULTS

We interviewed 150 PD patients and 150 matched controls. Cigarette smoking (ever vs. never smokers OR = 0.66, 95% CI = 0.41-1.05, p = 0.08) did not show a statistically significant association with PD. We observed an inverse association between alcohol drinking (ever vs. never OR = 0.61, 95% CI = 0.39-0.97, p = 0.037) and coffee consumption (ever vs. never OR = 0.16, 95% CI 0.05-0.46, p = 0.0001) and PD. These associations remained significant after adjustment for other covariates: OR for ever vs. never alcohol consumption was 0.62 (95% CI = 0.43-0.89, p = 0.009) and that for coffee drinking 0.19 (95% CI = 0.07-0.52, p = 0.001). Heavy coffee consumption confirmed the inverse association between coffee and PD (more than 81 cup/year vs. none: OR = 0.20, 95% CI = 0.08-0.47, p < or = 0.0001).

CONCLUSIONS

Consistent with previous studies, our results suggest an inverse association between coffee drinking, alcohol consumption and PD. The multiple inverse association observed may indicate a complex interaction between genetic and environmental factors.

Accuracy of death certificates for motor neuron disease and multiple sclerosis in the province of Palermo in southern Italy

Mortality studies based on death certificates (DCs) are relatively inexpensive and easy to conduct. Therefore, they are frequently used to evaluate variations of geographical and temporal patterns, particularly in uncommon diseases. Recent surveys of motor neuron disease (MND) and multiple sclerosis (MS) based on official mortality statistics in Italy showed a decreasing trend of mortality from northern to southern Italy. To evaluate if DCs are homogeneously recorded in Italy and whether or not they can be considered a good instrument for mortality studies, we assessed the accuracy of DCs for MND and MS in the province of Palermo, Italy, and compared our results with those reported in other studies. We searched the archives of the neurological clinic of the University of Palermo for patients affected by one of the two diseases who were residents and were diagnosed in Palermo province. We found 157 patients with definite MND and 360 with clinically definite MS. Seventy-eight out of the 157 MND patients and 43 out of the 360 MS patients had died. Considering the underlying cause of death, the true-positive rate was 48% [95% confidence interval (CI) 36-60%] for MND and 46% (95% Cl 30-62%) for MS. The rates we found for MND were lower than those reported either in Italy or worldwide. This result suggests caution in formulating gradient hypotheses for MND. Concerning MS, the rate we found was low, but similar to that found by others. This indicates that a mortality survey of MS based on DCs is unlikely to be contributory.

A transcranial magnetic stimulation study evaluating methylprednisolone treatment in multiple sclerosis

OBJECTIVE

To investigate the efficacy of two different high doses of intravenous methylprednisolone (IVMP) during Multiple Sclerosis (MS) relapses.

BACKGROUND

Transcranial Magnetic Stimulation (TMS) is the most sensitive neurophysiological ascertainment to quantify motor disability, to follow the recovery from an MS relapse, and to detect the response to treatment.

DESIGN AND METHOD

Twenty-four clinically definite relapsing - remitting MS patients presenting a relapse were randomly assigned to a treatment for 5 days with IVMP 1 or 2 g/day. The response to treatment of each patient was evaluated through Expanded Disability Status Scale (EDSS), Medical Research Council (MRC) score, and TMS by means of motor evoked potential (MEP) parameters.

RESULTS

Motor threshold (MT), central motor conduction time (CMCT) and MRC showed a higher improvement with the highest dose of IVMP. Silent period and EDSS improved with both treatments.

CONCLUSION

The dose of 2 g/day of IVMP is more effective in MS relapse.

Impact of sociodemographic characteristics on cognitive performance in an elderly Sicilian population

OBJECTIVE

To assess cognitive levels in an elderly Sicilian population and to evaluate the role of education and other sociodemographic characteristics in cognitive performance.

BACKGROUND

The pattern of cognitive performance in the elderly has not been investigated extensively in well-defined Italian populations. This study was conducted as part of a door-to-door survey of common neurologic disorders (the Sicilian Neuro-Epidemiologic Study project).

METHODS

Thirteen physicians administered an Italian version of the Short Portable Mental Status Questionnaire (SPMSQ) to all subjects aged 50 years or older who, on November 1, 1987, resided in either of two Sicilian municipalities (Terrasini, Palermo province, and Riposto, Catania province; n = 3,999). Performance was scored as the number of errors on the SMPSQ. To define cognitive impairment we corrected the score for education as suggested by Pfeiffer [J Am Geriatr Soc 1975;23:433-441].

RESULTS

The median SPMSQ score was equal to 2, and cognitive impairment was present in 4.6% of the subjects. In a bivariate analysis, age, sex, education, employment status at interview and principal lifetime occupation were all significantly associated with cognitive impairment. In a multivariate analysis, the same pattern was seen, except that principal lifetime occupation lost its significance.

CONCLUSION

Our findings suggest that age, sex, education and employment status are the sociodemographic characteristics associated with cognitive impairment in the elderly as measured by the SPMSQ.

High incidence and increasing prevalence of MS in Enna (Sicily), southern Italy

Twenty years after a first survey, a follow-up study was performed on the prevalence of MS in Enna (Sicily), southern Italy. The prevalence of definite MS rose from 53 to 120.2 per 100,000 population. The incidence of definite MS for the period 1986 to 1995 was 5.7 per 100,000 per year. The innermost part of Sicily shows an elevated prevalence of MS, second only to Sardinia in the Mediterranean area.

Door-to-door prevalence survey of epilepsy in three Sicilian municipalities

A door-to-door prevalence survey of epilepsy was conducted in 3 Sicilian municipalities, as of November 1, 1987. In phase 1, the screening by questionnaire of 24,496 eligible subjects (participation = 92%) identified 544 suspected to have epilepsy. In phase 2, neurological evaluation of the 544 subjects yielded 111 with epilepsy. Of the 111 subjects, 103 (93%) had been previously diagnosed, 68 (61%) were taking antiepileptic medication, and 81 (73%) had active epilepsy. Referring to the 81 subjects with active epilepsy, the seizure type was generalized in 60 (74%), partial in 19 (23%) and undetermined in 2 (3%). The prevalence of active epilepsy (per 1,000 population) was 3.3 overall, 3.5 for men and 3.2 for women. The age-specific patterns for active epilepsy differed by sex, with higher figures for men at younger ages (5-19 years) and older ages (50-99 years). The age-specific prevalence figures for active epilepsy were lower than those from previous Italian surveys.

Preparation, characterisation and photosensitivity studies of solid dispersions of diflunisal and Eudragit RS100 and RL100

Solid dispersions of diflunisal (DIF) with Eudragit RS100 (RS) and RL100 (RL) with different drug-to-polymer ratios were prepared by a solvent method (coevaporates) and were characterised in the solid state in comparison with the corresponding physical mixtures. The work was aimed at characterising the interactions occurring between DIF and RS or RL polymers, along with their influence on the in-vitro drug-dissolution pattern. The findings suggest that the drug did not change its crystalline form within the polymer network. Drug dispersion in the polymer matrix strongly influences its dissolution rate, which appears slower and more gradual while increasing the polymer ratios. Moreover, DIF is known to be a photosensitive compound, and its photoproduct has been found to be a toxic agent. This can be evidenced by testing red blood cell membranes for their resistance to the osmotic shock induced by UVA irradiation in the presence of DIF. The presence of some DIF/RS coevaporates was shown to reduce significantly the drug photosensitization process towards cell membranes. This suggests the possibility of combining the design of a drug delivery system with a photoprotective strategy.

Epidemiology of multiple sclerosis in Sicily

From epidemiological data obtained over more than 20 years by surveys conducted in different parts of Sicily, it is evident that Sicily is a high-risk area for multiple sclerosis (MS). This is in sharp contrast with the gradient hypothesis. High frequencies have been found in different parts of the island having different geoclimatic features, but at least two cities (Monreale and Enna) had had a prolonged Norman domination. This is in agreement with the hypothesis that MS originated in Northern Europe and spread around the world throughout the raids of the northern peoples. The increase in frequency estimated by follow-up and incidence studies is well established and is only in part linked to the improvement in diagnostic techniques. Finally, it is noteworthy that in the islands of Malta, a few sea miles away from Sicily, the MS prevalence rates are in the range of 4-8 cases per 100000 persons. This occurrence represents a natural model to investigate MS etiology through analytic studies and genetic analyses.

Incidence of multiple sclerosis in Bagheria City, Sicily, Italy

We investigated the incidence of multiple sclerosis (MS) in a Sicilian community located at sea level. The study was a retrospective search for MS patients. Incidence was studied in the period from 1 January 1985 to 31 December 1994. We searched for definite MS patients, according to Poser's criteria, among the population resident in Bagheria (Palermo province). There were 25 subjects affected by MS, of which 20 were incident MS patients. The average annual incidence was 4.4 per 100,000 persons (n = 453,385 person-years). The incidence increased over time (1985-1989 = 3.5, 1990-1994 = 5.3). A parallel decrease of the interval between onset and diagnosis of MS was observed (1985-1989, 3.7 years, 95% CI = 1.6-7.3; 1990-1994, 1.9 years, 95% CI = 1.0-3.3). These results confirm that MS is frequent in Sicily.

Is season of birth associated with multiple sclerosis?

OBJECTIVE

To compare the monthly distribution of multiple sclerosis (MS) patients' births with that of the Sicilian population.

BACKGROUND

Studies on the association between season of birth and risk of MS are scanty and controversial.

DESIGN AND METHODS

Archives of the Institute of Neuropsychiatry of the Universities of Palermo and Catania were searched up to 1995 for definite MS patients (McDonald & Halliday criteria). The monthly distribution of MS patients' births (N= 965) was compared with that of the Sicilian population (N= 5,608,307).

RESULTS

The distribution of births among MS patients compared with the general population was not different when tested by the chi2 statistic (P> 0.25). The Hewitt's non-parametric test for seasonality showed an excess of births between June and November among MS patients (P=0.004).

CONCLUSION

A different pattern of MS patients' births is observed in Sicily and in Northern countries.

Parkinson disease survival: a population-based study

OBJECTIVE

To evaluate whether the survival of patients with Parkinson disease (PD) is shorter than that of the general population.

DESIGN

Survival was investigated in a cohort of patients with PD previously identified during a population-based prevalence study (prevalence day, November 1, 1987, reference follow-up date, October 31, 1995). The survival of patients with PD was compared with that of a control sample randomly selected from the same population (2 controls for each case, matched for age, sex, and study municipality). The causes of death in the 2 groups were also compared. Both univariate and multivariate survival analyses were performed to investigate the association with disease-related variables.

SETTING

A door-to-door 2-phase prevalence survey performed in 3 Sicilian municipalities.

PATIENTS

Fifty-nine patients with PD and 118 controls.

RESULTS

Patients with PD showed a high risk of death (relative risk, 2.3; 95% confidence interval, 1.60-3.39). Greater age at November 1, 1987, high Hoehn-Yahr score, and lack of levodopa therapy were associated with a lower survival on univariate analysis. Multivariate analysis confirmed the association between shorter survival among patients with PD and greater age on November 1, 1987. One-way analysis of variance indicated a different effect of levodopa therapy according to age. Multivariate analysis did not confirm this finding. Pneumonia was the cause of death most frequently associated with PD.

CONCLUSION

This study indicates that patients with PD have a shorter survival time than the general population.

Exclusion of the Sonic Hedgehog gene as responsible for Currarino syndrome and anorectal malformations with sacral hypodevelopment

Anorectal malformations (ARMs) are common congenital anomalies that account for 1:4 digestive malformations. ARM patients show different degrees of sacral hypodevelopment while the hemisacrum is characteristic of the Currarino syndrome (CS). Cases of CS present an association of ARM, hemisacrum and presacral mass. A gene responsible for CS has recently been mapped in 7q36. Among the genes localized in this critical region, sonic hedgehog (SHH) was thought to represent a candidate gene for CS as well as for ARM with different levels of sacral hypodevelopment according to its role in the differentiation of midline mesoderm. By linkage analysis we confirmed the critical region in one large family with recurrence of CS. In addition, the screening of SHH in 7 CS and in 15 sporadic ARM patients with sacral hypodevelopment allowed us to exclude its role in the pathogenesis of these disorders.

Stroke incidence and survival in three Sicilian municipalities. Sicilian Neuro-Epidemiologic Study (SNES) Group

We investigated the incidence of first-ever stroke in three Sicilian municipalities over the years 1984-1987. Case ascertainment involved two approaches: a door-to-door two-phase prevalence survey and a study of death certificates. Only first-ever strokes occurring within the study time interval were included, and diagnoses were based on specified criteria. We found 138 subjects who had experienced a first stroke over 73 488 person-years; the average incidence rate (new cases per 1000 population per year) was 1.9 overall, 1.7 in men, and 2.1 in women. Incidence increased steeply with age and was similar in men and women. Incidence was similar in the three study municipalities. The overall case-fatality rate was 35% at 30 days and 22% at one week. Survival after stroke was similar in men and women but better in younger compared to older stroke patients. Comparisons with previous studies suggest the absence of major geographic variations in stroke incidence within Italy.

Population-based case-control study of essential tremor

Current epidemiologic data on the association between environmental factors and essential tremor (ET) are scanty. In a population-based case-control study we investigated the relationship between some putative risk factors and ET. In the present study, we included all subjects identified during a door-to-door prevalence survey in a Sicilian community, affected by ET, and alive on 1 November 1987 (n=31). Of the 31 prevalent cases of ET, we were able to contact 28 subjects. Twenty-eight controls were randomly selected from the general population and matched to each case for age and sex. Exposure variables were investigated by interviewing the patients and their controls or close relatives, using a structured questionnaire. The odds for habitual alcohol consumption were 0.3, indicating a protective effect. The odds for exposure to agricultural chemicals and domestic animals were 2.5 and 2.7, respectively, suggesting a role as potential risk factors. However, the associations found by us were not statistically significant.