Autopsy survey for Alzheimer's disease in Nigerian Africans: a preliminary report.

We carried out an autopsy survey on 198 brains of Nigerians aged 40 years and above to determine the occurrence of (neuropathognomonic) changes of Alzheimer's disease (AD) in our elderly patients. Forty five patients (23%) were above 65 years of age. Appropriately stained histological sections of various parts of the brains showed mild cortical neuronal loss and absence of neurofibrillary tangles, senile plaques and amyloid angiopathy--hallmarks of Alzheimer's disease and ageing reported in the Caucasians and Japanese.

Clinically-diagnosed dementing illnesses in Ibadan: features, types and associated conditions.

In this hospital-based study of dementing illnesses in Ibadan, 37 cases were seen over a 6 year period from 1984 to 1989 out of 57,440 cases admitted. The average hospital frequency was 64 cases per 100,000 admissions. Eighteen cases (48.7%) had vascular dementia. The other types encountered were: secondary dementias (8), mixed (5), probable primary degenerative (1) and the remaining 5 cases were unclassifiable. The associated conditions were mainly hypertension, parkinsonism, diabetes mellitus and benign prostatic hyperplasia. The findings confirm the relative rarity of primary degenerative dementia in Nigeria and raise the possibility of prevention of the predominant type by identifying the stroke-prone individuals early and intervening.

Alzheimer's disease in Nigeria.

The age-related dementias of the elderly (those aged 65 years or more) are of major public health importance in developed countries. Developing countries, most of which are undergoing epidemiological transition and greying of population, currently contain more than half of the world's population of elderly, a proportion that would reach 75% by 2020. Apart from reports from China, there is little or no information on the dementias of the elderly in developing countries. Alzheimer's disease, which accounts for two-thirds of dementia of the elderly in Caucasian population, is under-documented and believed to be rare in black Africans. But black Americans who are of black African lineage commonly suffer from Alzheimer's disease. A recent autopsy survey of the brains of elderly Nigerians showed absence of senile plaques and neurofibrillary tangles, the pathognomonic histologic lesions of Alzheimer's disease and ageing found in 25% to 80% of normal undemented elderly Caucasians and Japanese. In a community-based door-to-door survey of a population of 9000, including 932 elderly Nigerians, no subject with dementia as defined by DSM-IIIR was found, although there was significant decline of cognition with age, female sex and less than 6 years of formal education. The distribution of cognitive scores is a highly skewed unimodal curve. We emphasize the potential value of cross-cultural epidemiological studies of ethnic groups in different environments and with different prevalence ratios of Alzheimer's disease, in identifying putative environmental factors for this disease.

Cross-cultural studies in Alzheimer's disease.

The search for risk factors for Alzheimer's disease would be greatly enhanced by identification of populations with significantly different prevalence rates, particularly if these populations consisted of ethnic groups now living in different environments and cultures. Evidence is presented that two such groups are worthy of further study: subjects of African origin living in Africa and in the West and Native Americans living on and off reserves.

Screening for dementia in elderly Nigerians: results of the pilot test of a new instrument.

We developed a new instrument for the assessment of cognitive functions in elderly Nigerians as a preliminary step towards the determination of the burden of dementia in Nigerian Communities. The instrument was pilot tested on 250 cognitively-normal Nigerians and their scores compared with those of 15 subjects with clinically-diagnosed dementia. The cognitively normal subjects had a mean score of 24 (SD 2.3) while the cognitively-impaired subjects had a mean of 35 (SD 3.0) and p less than 0.01). Of those with normal cognition, subjects with at least 6 years of education had significantly lower mean scores than illiterates (p less than 0.005). The instrument was completed in 4 minutes in normal subjects as against 7 minutes in those with cognitive impairment. The 19 item instrument had a sensitivity of 80% and a specificity of 72% at a cut-off value of 27. With the elimination of 3 items related to information, the sensitivity and specificity increased to 93% and 83% respectively. We conclude that the 16 item version is adequate for a 2 stage study of dementia in this environment, its main role being that of screening in the first stage.

Influence of education on aspects of cognitive functions in non-demented elderly Nigerians.

Cognitive function was assessed in 930 elderly Nigerians living in an urban community by trained medical students who were blinded to the educational status of the subjects. They used a pretested and validated questionnaire. The subjects were later evaluated for the presence of dementia according to DSM-IIIR criteria by neurologists who then determined the educational status of the subjects. There were 361 males and 569 females with a mean age of 58.5 years (SD = 14.8). One hundred and sixty-one subjects (17%) with at least 6 years of education performed better on all aspects of cognition assessed (p less than 0.001). The differences in performance were statistically significant on assessment of general knowledge, intelligence, abstract thinking, depth of information and immediate recall (p less than 0.001) but not for calculation, orientation, attention and language comprehension. Our findings confirm the confounding effect of education on cognitive assessment and suggest the possibility of developing a short culture-free and educationally unbiased instrument for assessing cognitive functions in Nigerians.

Coexisting malignant melanoma and vitiligo in a Nigerian.

A case of malignant melanoma associated with vitiligo in a middle aged Nigerian is presented. The Association has been well documented in some other parts of the world, but this is the first of its type in the West African subregion. The occurrence of vitiligo in melanoma patients is generally believed to be beneficial, and has been well recognised to presage long time survival for the patient. The course of events in our patient is still being observed.