Dallas W. Anderson

Prevalence of Parkinson's disease in the biracial population of Copiah County, Mississippi

A door-to-door survey of major neurologic disorders was conducted in the essentially biracial population of Copiah County, MS, using a pretested screening questionnaire. All those suspected of having Parkinsons disease were requested to have a neurologic examination by board-certified neurologists. The study also included those living in institutions. The prevalence of Parkinsons disease (age 40 +) was 347 per 100,000 inhabitants. No substantial differences in the age-adjusted prevalence ratios by race or by sex were found in the population studied. Age-specific prevalence ratios for Parkinsons disease increase with advancing age. Over 40% of identified cases were newly diagnosed during the study.

Norms for the Mini-Mental State Examination in a healthy population

Background: Although the Mini-Mental State Examination (MMSE) is widely used in clinical practice, few norms exist for healthy populations covering a broad range of ages. Objective: To obtain MMSE norms specific for age, gender, and education in healthy adults. Methods: From the population registers of seven communities across Italy, we selected a proportionate random sample of residents age 20 to 79 years to evaluate their health status with respect to conditions affecting cognitive performance. This sample yielded 908 persons who were deemed to be without cognitive impairment and who were then given the MMSE. We calculated fifth percentile norms and presented them as step functions. We then validated the norms as a screening tool for dementia in persons age 65 to 79 years. The validation was based on unpublished data from a separate study and involved estimates of sensitivity and specificity. Results: The norms declined with advancing age, especially for less educated women. Given any age and sex, the norms were higher for individuals with higher educational levels. In screening for dementia, the norms had a sensitivity of 85% and a specificity of 89%. Conclusions: When using MMSE scores, it is important to account for age, gender, and education, especially in populations where the educational level is low. Expressing MMSE norms as step functions provides an easy-to-use tool for neurologists and other clinicians.

A population perspective on diagnostic criteria for Parkinson's disease

For Parkinsons disease (PD), little is known about how the choice of diagnostic criteria affects research results. Using data on PD from three community studies (from Argentina, the Netherlands, Italy), we compared the impact on prevalence of several sets of diagnostic criteria. Each set was based on cardinal signs—resting tremor, bradykinesia, rigidity, impaired postural reflexes—and required that other parkinsonism be excluded. Some sets had additional requirements related to duration of symptoms, asymmetry of signs, or response to medication. In terms of prevalence, much lower estimates were associated with the requirements of asymmetry of signs and response to medication. The assessment of these clinical features may not be practical in community studies. Impaired postural reflexes, as a cardinal sign, seemed superfluous. For community studies of PD, we recommend the following diagnostic criteria: at least two of resting tremor, bradykinesia, or rigidity, in the absence of other apparent causes of parkinsonism.

Prevalence and Clinical Features of Epilepsy in a Biracial United States Population

Summary: A need for prevalence information emphasizing racial differences prompted a door‐to‐door survey of all residents of Copiah County, Mississippi. The fieldwork involved a complete census and an extensive screening questionnaire inquiring about diagnoses, signs, and symptoms of neurologic disease. Residents who lived in institutions or had screening responses suggestive of epilepsy were requested to have an examination by neurologists who used defined diagnostic criteria. Prevalence day was 1 January 1978, and the survey yielded prevalence ratios of 1,043/100,000 inhabitants for epilepsy and 678/100,000 inhabitants for active epilepsy. Age‐adjusted prevalence ratios were somewhat higher for males and for blacks. Of the 246 identified cases of epilepsy, 37% were judged symptomatic. The leading (putative) cause was head trauma, especially among white males. About 57% of the 246 cases had been evaluated previously by a neurologist or neurosurgeon, while 7% had never been evaluated medically before the survey.

Validating screening instruments for neuroepidemiologic surveys: Experience in Sicily☆

In a hospital setting in Sicily, we assessed a screening instrument developed for a prevalence survey of parkinsonism, peripheral neuropathies, stroke, and epilepsy. The subjects consisted of (1) hospital patients with any of the above-mentioned diseases, to investigate sensitivity; and (2) hospital visitors free of all these diseases, to investigate specificity. The standard for comparison was a clinical evaluation based on specified criteria. Trained interviewers administered the screening instrument, asking subjects to answer symptom questions and to perform simple physical tasks. For the questions and tasks together, the sensitivity estimates were 100% for parkinsonism (n = 21), 96% for peripheral neuropathies (n = 22), 96% for stroke (n = 22), and 96% for epilepsy (n = 22), while the specificity estimate was 86% (n = 21). Analogous estimates were computed for the set of questions, for the set of tasks, and for each question and task individually. Despite limitations in our approach, we concluded that the screening instrument would be adequate for its intended use.

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.

Problems and Issues with Door-To-Door, Two-Phase Surveys: An Illustration from Central Spain

In 1994–1995, a screening and examination survey was conducted to ascertain the prevalence of dementia, Parkinson’s disease and stroke in two urban communities and one rural community of central Spain. We use this survey to illustrate many nonclinical aspects of conducting two-phase prevalence surveys. Special emphasis is given to two common weaknesses in such surveys: screening nonparticipation and screening validation.

Door-to-Door Prevalence Survey of Neurological Diseases in a Sicilian Population

In three municipalities of Sicily, a prevalence survey of major neurological diseases was conducted door-to-door using screening and examination to find cases. This was the first large-scale neuroepidemiologic survey of that type undertaken in Italy: 24,496 persons were screened yielding 1,538 positives, of whom 1,408 were examined directly by neurologists and 110 were evaluated on the basis of existing medical documentation. In the article, we provide (1) a description of the population investigated and the survey methods employed; (2) details of the cooperation and the attrition experienced in the survey; and (3) age and sex tallies for the study population, including some on education level and occupation.

Prevalence of Parkinson's disease and related disorders in the elderly population of greater Beijing, China.

A lower prevalence of Parkinsons disease (PD) has been reported for Chinese populations, but it is unclear whether this observation reflects a lower disease risk or is an artifact of case finding. We ascertained the prevalence of PD in elderly residents of an area that was a composite of 27 urban and rural communities of Greater Beijing, China. A team of university neurologists went door‐to‐door throughout the study area, examining 5,743 residents (at age 55 years or older) and made preliminary determinations of which residents had PD or other types of parkinsonism. Final determinations were made after follow‐up and reevaluation of those persons who were either deemed to have parkinsonism or were suspected of having the condition (n = 144; median follow‐up = 40 months). Based on stringent diagnostic criteria, 110 persons were identified to have parkinsonism, of whom 64 (58%) had PD. The prevalence of PD increased with advancing age and was about 1% overall and for each gender. In rural communities, 22 persons had PD, but 20 persons (91%) were first diagnosed for this condition by the study neurologists. The prevalence figures obtained in this study are similar to some of the highest prevalence figures reported in the West.

Autopsy patterns for Parkinson’s disease and related disorders in Olmsted County, Minnesota

Article abstract Using a records-linkage system, we determined the frequency and distribution of brain autopsies in residents of Olmsted County, Minnesota, in whom parkinsonism developed during 1976 through 1990. Of the 364 incident cases identified, 235 patients were deceased at the time of record abstraction. The overall autopsy rate was low (23%). Diagnostic certainty (for PD), diagnostic type (PD versus other parkinsonism), sex, age at death, and location at death were important selection factors for autopsy.