Prestroke cognitive decline in africans: Prevalence, predictors and association with poststroke dementia

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Highlights

  • Prestroke cognitive decline is common in Africans.

  • Assessment of prestroke cognitive decline is feasible in this population.

  • Identification of prestroke neurocognitive problems have prognostic values.

Abstract

Objectives

Pre-existing cognitive decline is a risk factor for stroke onset and poststroke dementia. There is a knowledge gap on prestroke cognitive decline in indigenous Africans. We estimated prevalence and predictors of prestroke cognitive decline, as well as its association with poststroke dementia at one year in Nigerian survivors of a first ever stroke.

Methods

Prospective observational study. Prestroke cognitive decline was ascertained using an average score > 3.31 on the 16-item Informant Questionnaire for Cognitive Decline in the Elderly (IQ-CODE). Poststroke dementia was ascertained according to the ‘National Institute of Neurological Disorders and Stroke and the Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN) criteria’. Associations were investigated using multivariate logistic regression models and presented as odds ratios (O.R) within 95% confidence intervals (C.I).

Results

Among 150 stroke survivors, prestroke cognitive decline was found in 25 (16.7%, 95% C.I = 11.5%–23.6%). In analyses adjusting for the effect of age, education and stroke severity, prestroke cognitive decline was associated with diabetes mellitus (O.R = 3.0, 95% C.I = 1.2–7.6). Ten (62.5%) survivors in the prestroke cognitive decline sub-sample developed dementia at one-year poststroke. In analyses adjusting for the effects of age, education, stroke severity and comorbid diabetes mellitus, survivors with prestroke cognitive decline had six times the odds of dementia at one year poststroke (O.R = 6.2, 95% C.I = 1.3–30.4).

Conclusion

Prestroke cognitive decline is common, assessment is feasible and identifying pre-stroke problems has prognostic implications.

Introduction

Pre-existing cognitive decline is a risk factor for stroke onset [1], hospital discharge to nursing home [2], persistent poststroke disability [3] and mortality [2]. Yet, prestroke cognitive decline is mostly unidentified and undiagnosed [4]. Even when identified, attending health staff have been shown to express doubt about the value of stroke rehabilitation for those with pre-existing cognitive decline [4,5].

Due to factors such as physical limitation, stigma and cost of biomedical healthcare, there is low healthcare utilization for stroke in Nigeria. Many stroke survivors in the country context have been known to prefer complementary and alternative care for their conditions [6]. Stroke survivors with pre-existing cognitive decline, in particular, are less likely to be referred or admitted to stroke rehabilitation programs. Better understanding of prestroke cognitive decline and its correlates should thus be of interest to poststroke rehabilitation efforts, as well as policy regarding identification of cognitive decline in the population at increased risk of stroke.

Unrecognised cognitive decline in the months and years preceding stroke onset may also account for a proportion of the risk of post-stroke dementia [7]. However, studies on the extent of impact of prestroke cognitive decline on poststroke dementia in the global literature have tended to produce conflicting results. In some studies, poorer prestroke cognitive functioning was associated with greater risk of dementia after stroke [7,8]. Contrariwise, 14 out of 19 studies investigating this mechanistic link in the large systematic review and meta-analyses by Pendlebury and Rothwell [9] did not find a statistical association between prestroke cognitive decline and poststroke dementia.

More recent evidence suggest that race and ethno-geographical factors may modify both the risk and trajectory of cognitive decline leading up to dementia in the stroke population [10]. In a large representative United States cohort of persons who were aged 45 years or older [11], African-Americans had a faster decline in global cognitive functioning after stroke compared with other race-ethnicities. Yet, the impact of prestroke cognitive decline on poststroke dementia has not been prospectively examined in indigenous Africans who are resident in Africa. Such information is desirable globally, but especially so in sub-Saharan Africa (SSA) where the burden of poststroke cognitive disorders is potentially higher compared with other populations [12]. Notably, risk factors such as diabetes and hypertension as well as socio-economic indicators of poststroke dementia are significantly higher in SSA [12].

Two previous studies from West Africa [13,14], the source population of 71% of African-Amerians [15], implemented a onetime cross-sectional assessment of cognitive functioning in a heterogenous sample of stroke survivors. In the present study, which is based on a homogenous sample of Nigerian survivors of a first ever stroke, we aimed to; 1). Estimate prevalence and factors associated with pre-stroke cognitive decline and 2), describe the relationship between prestroke cognitive decline and poststroke dementia at one year.

Section snippets

Material and methods

This report conforms with the guidelines for Strengthening the Reporting of Observational Studies in Epidemiology (STROBE).

Subject characteristics

Characteristics of 150 stroke survivors included in the study is presented in Table 1. There were 89 males and 61 females. Their mean age was 60.2 (±12.8) years, with 82 (54.7%), 58 (38.7%) and 10 (6.7%) having ischaemic, haemorrhagic and haemorrhagic-infarct stroke subtypes, respectively.

The mean age of caregivers who provided information about prestroke cognitive statuses of participants was 38.7 (±12.8) years. The majority were women (68.6%) with at least high school education (92.7%). They

Discussion

In this sample of adult Nigerian survivors of a first ever stroke, we found a prevalence estimate of 16.7% for cognitive decline occurring in the years and up to one month before stroke onset. Prestroke cognitive decline was independently associated with diabetes mellitus. Approximately 62.5% of survivors with prestroke cognitive decline developed poststroke dementia. Cognitive decline in the years and up to a month before stroke was associated with six times the adjusted odds of dementia at

Authors' statement

All Items in the STROBE checklist relevant to cross-sectional study has been included in this manuscript.

Empty CellItem NoRecommendation
Title and abstract1(a) Indicate the study's design with a commonly used term in the title or the abstract
(b) Provide in the abstract an informative and balanced summary of what was done and what was found
Introduction
Background/rationale2Explain the scientific background and rationale for the investigation being reported
Objectives3State specific

Funding

This work was supported by the Medical Education Partnership Initiative of Nigeria- Junior Faculty Research Training Program [under grant number D43TW010140].

Previous presentation

None. The content is solely the responsibility of the authors.

Declaration of Competing Interest

On behalf of all authors, the corresponding author states that there are no conflicts of interest.

Acknowledgements

We thank the participants and data collection team.

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