A search of the 1988 mortality files, created by the National Center for Health Statistics (NCHS), looking for individuals who died with an ICD-9 diagnosis of PD revealed racial differences. Whether PD was the underlying cause of death, a contributing cause, or just a diagnosis that people carried, whites had significantly higher rates than blacks. This study confirmed the findings of earlier reports that had mainly looked at census data from 1959—1961. These studies were obviously limited by the fact that they relied both on a person carrying the diagnosis at the time of death and that death certificates were completed in a consistent fashion throughout the country.
All residents of Copiah County, Mississippi as of January 1,1978 were visited by nonmedical lay-interviewers who administered an extensive questionnaire that included questions on the symptoms of PD among other topics. Individuals who had features suggestive of PD were subsequently examined by a neurologist. Ninety-seven percent of the households, containing almost 24,000 residents, agreed to participate in the study. Although 49% of the total population was black and 50% was white, the study focused on individuals over 40 years of age, of whom 60% were white and 39% were black. A definitive diagnosis of PD required the presence of two or more of the following signs: resting tremor, bradykinesia, rigidity, parkinsonian gait or posture, retropulsion, masked facies, and micro-graphia. A possible diagnosis of PD required the presence of one of these cardinal signs and the equivocal presence of at least one other. They found 31 individuals—13 of whom were newly diagnosed as a result of the study—with PD or possible PD in this study. There were no differences in the occurrence of PD in blacks (12 cases in almost 3,600 over 40) as opposed to whites (19 cases in almost 5,400 over 40) when one looked at the total number of PD cases. However, when definite and possible cases were examined separately, it was found that whites had a greater proportion of definite cases than blacks. Fifty-eight percent of blacks and 32% of whites had not been diagnosed previously. order levitra
The same research group that carried out the door-to-door study in Copiah County sought to compare the prevalence of PD in Copiah County to its prevalence in Nigeria, on the assumption that West Africa was the ancestral origin for a large proportion of blacks residing in the United States, including Mississippi. They chose a town in Nigeria with a stable population of 20,000. Over 99% of households cooperated and, of the 3,412 people over the age of 40, only two individuals were found to have PD. The authors felt that the reduced survival rates in Nigeria only partly accounted for the discrepancy in prevalence between locations and subsequently hypothesized that environmental agents were responsible for observed differences.
Postmortem Findings in an African Population
The only published postmortem survey for PD in Africa was carried out in West Africa. This was not a true epidemiologic study. The researchers simply examined the brains of 94 patients who had been reported to be neurologically normal and found nigral Lewy bodies accompanied by mild neuronal loss in five patients. The authors felt that this incidence was similar to the figures previously reported in the UK and USA. canadian antibiotics
Inherited Parkinson’s Disease in Families of African Ancestry
None of the African studies intentionally ascertained whether a family history was present. Osun-tokun did report that of the 217 patients with Parkinsonism seen in Nigeria over a 10-year period, two had volunteered a family history of PD. But we do not know whether the figure would have been higher had the question been asked to every patient. A study looking for PD in first-degree relatives (FDRs) of affected PD patients found that it was two-and-a-half times more common in relatives of people with PD than controls. In 19 cases, there was an FDR affected, and in three of these, there were two affected FDRs— one of which was an African-American family.