The association of Carotid Doppler Ultrasound findings and cognitive state in the elderly in Wakiso District, Uganda

Abstract

Background Carotid artery disease which includes carotid artery stenosis, plaques, clots and increased intima media thickness, have been reported by many studies to be associated with dementia. Dementia is an end stage of a continuum of symptoms ranging from minor usually asymptomatic cognitive impairment to overt clinical picture of dementia. Age is the number one risk factor in cognitive impairment, studied extensively in Alzheimer’s disease and carotid artery disease. Other risk factors studied in carotid artery disease, include atherosclerosis, arteriosclerosis, shorter years in school, history of hypertension, diabetes mellitus, stroke and depression. There is a paucity of literature on the detection of carotid artery disease in the elderly using ultrasound in African population and more particularly in Uganda. Main Objective To determine the prevalence of abnormal carotid Doppler Ultrasound findings and their association with cognitive function among the elderly in Wakiso district, Uganda in 2018. Methods This was a cross-sectional study carried out amongst the elderly in the communities of Wakiso, Nansana and Busukuma from October 2017 to February 2018. Two hundred twelve (212) participants who met the inclusion criteria were scanned. A Mini Mental State Exam (MMSE) was administered and the total score obtained. MMSE scores range between 0 to 30. Four categories of cognitive; Normal, Mild/Early, Moderate and Severe with respective scores of 30-25, 24-21, 21-10, 9-0 were used. Scanning was done using a Shantou Institute of ultrasonic instrument (SIUI) 5300 MODEL 2015, with a linear (5-12 MHz) high frequency probe. Findings included; the presence of plaque, its location and characteristics; the minimal residual lumen of Common Carotid Artery (CCA) and internal carotid artery (ICA); Intimal media thickness of CCA and ICA; and the flow pattern within each vessel. Analysis was performed using STATA version 12.0. The association was between CAD and cognitive state was assessed using logistic regression. Significance was set at P-value of 0.05 or less. xiii Results Of the 210 elderly scanned, the prevalence of CAD was 21.4%. The gender-specific prevalence showed two-times prevalence of CAD in females as compared to males but was not statistically significant (Respective Male and female prevalence and 95% CI; 16.7 [9.04, 28.69] and 23.3 [17.19, 30.86]. The prevalence of CAD to be increasing with age, from 16% in the first decade above 60 years to 42% in the 80 years and above. The presence of CAD was associated with an abnormal cognitive function at both univariate and multivariate analysis with respective OR = 3.8 (95% CI = 1.90 – 7.54, p-value = 0.0001) and OR= 3.4 (95% CI=1.38-8.15, p-value=0.007). Finally, the cognitive function distribution was 43.8%, 19%, 34.3% and 2.9% within the normal, mild, moderate, and severe cognitive function status respectively. Conclusion The prevalence of carotid artery disease is relatively high (21.4%) in the elderly population in Wakiso district, Uganda which is comparable to the western world. Carotid artery disease (CAD) is associated with abnormal cognitive function and the majority of the patients need assistance in their daily activities. A relationship between low MMSE and carotid plaques, increased intima media thickness (IMT) is shown in this study. This shows the usefulness of ultrasound as a tool in further non-invasive exploration of vascular dementia.