In tandem with the ever‐increasing aging population in low and middle‐income countries, the burden of dementia is rising on the African continent. Dementia prevalence varies from 2.3% to 20.0% and ...incidence rates are 13.3 per 1000 person‐years with increasing mortality in parts of rapidly transforming Africa. Differences in nutrition, cardiovascular factors, comorbidities, infections, mortality, and detection likely contribute to lower incidence. Alzheimer's disease, vascular dementia, and human immunodeficiency virus/acquired immunodeficiency syndrome–associated neurocognitive disorders are the most common dementia subtypes. Comprehensive longitudinal studies with robust methodology and regional coverage would provide more reliable information. The apolipoprotein E (APOE) ε4 allele is most studied but has shown differential effects within African ancestry compared to Caucasian. More candidate gene and genome‐wide association studies are needed to relate to dementia phenotypes. Validated culture‐sensitive cognitive tools not influenced by education and language differences are critically needed for implementation across multidisciplinary groupings such as the proposed African Dementia Consortium.
We reviewed recent literature on prevalence and interventional approaches for cognitive impairment in the context of HIV infection alongside current controversies and challenges around its ...nomenclature, screening, and diagnosis.
Prevalence estimates for HIV-associated neurocognitive disorder (HAND) indicate that HAND remains highly prevalent despite combination antiretroviral treatment (cART) widely used. The available data are heterogeneous, particularly in sub-Saharan Africa (SSA) where recent reviews indicate substantial heterogeneity, wide prevalence estimates and lack of data from the majority SSA countries, despite them currently experiencing the greatest burden worldwide of both HIV and HAND.Several alternative approaches to diagnosis and classification of cognitive impairment in HIV have been published, taking into account changing clinical phenotypes.
Cognitive impairment remains a significant challenge in the care of people living with HIV despite advances in treatment. Ongoing controversies exist around nomenclature and classification, screening measures, and the phenotype and aetiology of observed impairments. Two current areas of research priority and focus include understanding current phenotypes of individuals living and ageing with treated HIV and differing levels of risk for HAND in these phenotypes, alongside the effects of commonly occurring comorbidities.The current evidence base for interventional approaches is limited, but growing. The most promising avenues appear to be multidisciplinary. These are currently focussed on high income settings rather than SSA where the majority of people living with HIV, and affected by cognitive impairment in the context of HIV, currently reside.
Objectives
Depression is the commonest mental disorder in older adults worldwide, affecting 7% of the world’s older population and accounting for 5.7% of years lived with disability among adults aged ...over 60 years. We conducted a secondary data analysis to determine the point prevalence, associated risk factors and treatment gap for DSM‐IV depression among older adults in the Hai District, rural Tanzania.
Methods
The primary data source was a cross‐sectional two‐stage community‐based dementia study where older adults aged ≥70 years (n = 296) were fully‐assessed for dementia and depression in the second stage. Age‐adjusted prevalence of depression was determined based on the WHO standard population using the Direct Method. Univariate and multivariate logistic regression models were performed.
Results
Of the 296 older adults assessed for depression, 48 were diagnosed with depression based on Diagnostic and Statistical Manual of Mental Disorders‐IV criteria. The median (Inter Quartile Range; QR) age was 80 (75–88) years. Age‐adjusted point prevalence of depression was 21.2% (95% CI: 16.6–21.9) and the treatment gap for depression was 100%. There was reduced odds of depression in older adults who rated their physical health as good or very good (adjusted odds ratio AOR = 0.22; 95%CI: 0.10–0.46; p < 0.001), or moderate (AOR 0.26; 95%CI: 0.10–0.66; p = 0.005).
Conclusions
Depression in older adults is associated with physical health status and there is an alarmingly high treatment gap. Future research on depression in older adults should focus on effective interventions to address physical morbidity, psychosocial factors and the treatment gap.
Key Points
Despite depression being the commonest mental disorder in older adults reported worldwide, in Sub‐Saharan Africa, the epidemiological data on depression in this population group are limited.
We found point prevalence estimates of depression in older adults similar to those reported in community‐based studies in high income countries.
Self‐rated overall physical health status was associated with depression in older adults.
Future research on depression in older adults should focus on the physical morbidity, psychosocial factors and the treatment gap.
Introduction
With no treatment for dementia, there is a need to identify high risk cases to focus preventive strategies, particularly in low‐ and middle‐income countries (LMICs) where the burden of ...dementia is greatest. We evaluated the risk of conversion from mild cognitive ompairment (MCI) to dementia in LMICs.
Methods
Medline, Embase, PsycINFO, and Scopus were searched from inception until June 30, 2020. The search was restricted to observational studies, conducted in population‐based samples, with at least 1 year follow‐up. There was no restriction on the definition of MCI used as long as it was clearly defined. PROSPERO registration: CRD42019130958.
Results
Ten thousand six hundred forty‐seven articles were screened; n = 11 retained. Of the 11 studies, most were conducted in China (n = 7 studies), with only two studies from countries classified as low income. A qualitative analysis of n = 11 studies showed that similar to high‐income countries the conversion rate to dementia from MCI was variable (range 6.$.$0%–44.$.$8%; average follow‐up 3.$.$7 years standard deviation = 1.$.$2). A meta‐analysis of studies using Petersen criteria (n = 6 studies), found a pooled conversion rate to Alzheimer's disease (AD) of 23.$.$8% (95% confidence interval = 15.$.$4%–33.4%); approximately one in four people with MCI were at risk of AD in LMICs (over 3.$.$0–5.$.$8 years follow‐up). Risk factors for conversion from MCI to dementia included demographic (e.g., age) and health (e.g., cardio‐metabolic disease) variables.
Conclusions
MCI is associated with high, but variable, conversion to dementia in LMICs and may be influenced by demographic and health factors. There is a notable absence of data from low‐income settings and countries outside of China. This highlights the urgent need for research investment into aging and dementia in LMIC settings. Being able to identify those individuals with cognitive impairment who are at highest risk of dementia in LMICs is necessary for the development of risk reduction strategies that are contextualized to these unique settings.
Introduction
Although limited, existing epidemiological data on dementia in sub‐Saharan Africa indicate that prevalence may be increasing; contrasting with recent decreases observed in high‐income ...countries. We have previously reported the age‐adjusted prevalence of dementia in rural Tanzania in 2009–2010 as 6.4% (95% confidence interval CI 4.9–7.9) in individuals aged ≥70 years. We aimed to repeat a community‐based dementia prevalence study in the same setting to assess whether prevalence has changed.
Methods
This was a two‐phase door‐to‐door community‐based cross‐sectional survey in Kilimanjaro, Tanzania. In Phase I, trained primary health workers screened all consenting individuals aged ≥60 years from 12 villages using previously validated, locally developed, tools (IDEA cognitive screen and IDEA‐Instrumental Activities of Daily Living questionnaire). Screening was conducted using a mobile digital application (app) on a hand‐held tablet. In Phase II, a stratified sample of those identified in Phase I were clinically assessed using the DSM‐5 criteria and diagnoses subsequently confirmed by consensus panel.
Results
Of 3011 people who consented, 424 screened positive for probable dementia and 227 for possible dementia. During clinical assessment in Phase II, 105 individuals met DSM‐5 dementia criteria. The age‐adjusted prevalence of dementia was 4.6% (95% CI 2.9–6.4) in those aged ≥60 years and 8.9% (95% CI 6.1–11.8) in those aged ≥70 years. Prevalence rates increased significantly with age.
Conclusions
The prevalence of dementia in this rural Tanzanian population appears to have increased since 2010, although not significantly. Dementia is likely to become a significant health burden in this population as demographic transition continues.
Key Points
Using similar methodology, 9 years later, the prevalence of dementia appears to be increasing in Tanzania rather than decreasing, as observed in high‐income countries.
Objectives
HIV‐associated neurocognitive disorder (HAND), although prevalent, remains a poorly researched cause of morbidity particularly in sub‐Saharan Africa (SSA). We aimed to explore the risk ...factors for HAND in people aged 50 and over under regular follow‐up at a government HIV clinic in Tanzania.
Methods
HIV‐positive adults aged 50 years and over were approached for recruitment at a routine HIV clinic appointment over a 4‐month period. A diagnostic assessment for HAND was implemented, including a full medical/neurological assessment and a collateral history from a relative. We investigated potential risk factors using a structured questionnaire and by examination of clinic records.
Results
Of the cohort (n = 253), 183 (72.3%) were female and the median age was 57 years. Fifty‐five individuals (21.7%) met the criteria for symptomatic HAND. Participants were at a greater risk of having symptomatic HAND if they lived alone odds ratio (OR) = 2.566, P = .015, were illiterate (OR 3.171, P = .003) or older at the time of HIV diagnosis (OR = 1.057, P = .015). Age was correlated with symptomatic HAND in univariate, but not multivariate analysis.
Conclusions
In this setting, HIV‐specific factors, such as nadir CD4 count, were not related to symptomatic HAND. The “legacy theory” of early central nervous system damage prior to initiation of anti‐retroviral therapy initiation may contribute, only in part, to a multifactorial aetiology of HAND in older people. Social isolation and illiteracy were associated with symptomatic HAND, suggesting greater cognitive reserve might be protective.
In Mediterranean countries, adherence to a traditional Mediterranean dietary pattern (MedDiet) is associated with better cognitive function and reduced dementia risk. It is unclear if similar ...benefits exist in non-Mediterranean regions.
The aims of this study were to examine associations between MedDiet adherence and cognitive function in an older UK population and to investigate whether associations differed between individuals with high compared with low cardiovascular disease (CVD) risk.
We conducted an analysis in 8009 older individuals with dietary data at Health Check 1 (1993–1997) and cognitive function data at Health Check 3 (2006–2011) of the European Prospective Investigation into Cancer and Nutrition–Norfolk (EPIC-Norfolk). Associations were explored between MedDiet adherence and global and domain-specific cognitive test scores and risk of poor cognitive performance in the entire cohort, and when stratified according to CVD risk status.
Higher MedDiet adherence defined by the Pyramid MedDiet score was associated with better global cognition (β ± SE = −0.012 ± 0.002; P < 0.001), verbal episodic memory (β ± SE = −0.009 ± 0.002; P < 0.001), and simple processing speed (β ± SE = −0.002 ± 0.001; P = 0.013). Lower risk of poor verbal episodic memory (OR: 0.784; 95% CI: 0.641, 0.959; P = 0.018), complex processing speed (OR: 0.739; 95% CI: 0.601, 0.907; P = 0.004), and prospective memory (OR: 0.841; 95% CI: 0.724, 0.977; P = 0.023) was also observed for the highest compared with the lowest Pyramid MedDiet tertiles. The effect of a 1-point increase in Pyramid score on global cognitive function was equivalent to 1.7 fewer years of cognitive aging. MedDiet adherence defined by the Mediterranean Diet Adherence Screener (MEDAS) score (mapped through the use of both binary and continuous scoring) showed similar, albeit less consistent, associations. In stratified analyses, associations were evident in individuals at higher CVD risk only (P < 0.05).
Higher adherence to the MedDiet is associated with better cognitive function and lower risk of poor cognition in older UK adults. This evidence underpins the development of interventions to enhance MedDiet adherence, particularly in individuals at higher CVD risk, aiming to reduce the risk of age-related cognitive decline in non-Mediterranean populations.
The true global burden of vascular cognitive impairment (VCI) is unknown. Reducing risk factors for stroke and cardiovascular disease would inevitably curtail VCI.
The authors review current ...diagnosis, epidemiology, and risk factors for VCI. VCI increases in older age and by inheritance of known genetic traits. They emphasize modifiable risk factors identified by the 2020 Lancet Dementia Commission. The most profound risks for VCI also include lower education, cardiometabolic factors, and compromised cognitive reserve. Finally, they discuss pharmacological and non-pharmacological interventions.
By virtue of the high frequencies of stroke and cardiovascular disease the global prevalence of VCI is expectedly higher than prevalent neurodegenerative disorders causing dementia. Since ~ 90% of the global burden of stroke can be attributed to modifiable risk factors, a formidable opportunity arises to reduce the burden of not only stroke but VCI outcomes including progression from mild to the major in form of vascular dementia. Strict control of vascular risk factors and secondary prevention of cerebrovascular disease via pharmacological interventions will impact on burden of VCI. Non-pharmacological measures by adopting healthy diets and encouraging physical and cognitive activities and urging multidomain approaches are important for prevention of VCI and preservation of vascular brain health.
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