MEDICC Review

Levels of Vitamins and Homocysteine in Older Adults with Alzheimer Disease or Mild Cognitive Impairment in Cuba
October 2020, Vol 22, No 4

INTRODUCTION Age-related cognitive disorders, including Alzheimer disease, are among the main causes of disability and dependence in older adults worldwide. High blood homocysteine levels (hyperhomocysteinemia) are a risk factor for diseases whose metabolism involves different B vitamins. Antioxidant vitamins provide a protective effect by mitigating oxidative stress generated by these diseases. Epidemiological studies have presented varying results on the relationships between blood levels of these vitamins and such cognitive disorders.

OBJECTIVE Evaluate the association of vitamin and homocysteine levels with mild cognitive impairment and Alzheimer disease in a group of Cuban older adults.

METHODS A cross-sectional study was conducted in Havana, Cuba, of 424 persons aged ≥65 years: 43 with Alzheimer disease, 131 with mild cognitive impairment, and 250 with no signs of cognitive impairment. Dementia was diagnosed using criteria of the International 10/66 Dementia Research Group and Diagnostic and Statistical Manual of Mental Disorders (DSM IV), and mild cognitive impairment was diagnosed using Petersen’s criteria. Blood levels of vitamins (thiamine, B-2, folate, B-12, C and A) and homocysteine were measured by standard procedures. Analysis of variance for continuous variables and percentage comparison tests for dichotomous variables were used to compare groups.

RESULTS Persons with Alzheimer disease presented significantly lower levels of vitamins B-2, C and A than healthy participants (p <0.05). Homocysteine levels were significantly higher in those with Alzheimer disease and mild cognitive impairment than in participants with no cognitive impairment (p <0.05). Statistically, levels of thiamine, folic acid, and vitamin B-12 were not significantly different across groups. Compared with those without cognitive impairment, prevalence rates (PR) in the Alzheimer group were significantly higher for hyperhomocysteinemia (PR = 3.26; 1.84–5.80) and deficiency of all B vitamins: thiamine (PR = 1.89; 1.04–3.43), B-2 (PR = 2.85; 1.54–5.26), folate (PR = 3.02; 1.53–5.95), B-12 (PR = 2.21; 1.17–4.19), vitamin C (PR = 3.88; 2.12–7.10) and A (PR = 5.47; 3.26–9.17). In mild cognitive impairment, prevalence rates were significantly higher for hyperhomocysteinemia (PR = 1.42; 1.08–1.87), vitamin B-2 deficiency (PR = 1.70; 1.24–2.32) and vitamin A deficiency (PR =1.88; 1.05–3.38).

CONCLUSIONS Hyperhomocysteinemia and various vitamin deficiencies are related to Alzheimer disease and mild cognitive impairment. Longitudinal studies are needed to further elucidate the relationship between different nutritional biomarkers and dementia. A better understanding of this relationship could provide a basis for therapeutic and preventive strategies.

KEYWORDS Vitamins, homocysteine, geriatrics, Alzheimer disease, cognitive impairment, Cuba

Aging and Alzheimer is a prospective, longitudinal cohort study involving 2944 adults aged ≥65 years from selected areas in Cuba’s Havana and Matanzas Provinces. This door-to-door study, which began in 2003, includes periodic assessments of the cohort based on an interview; physical exam; anthropometric measurements; and diagnosis of dementia and its subtypes, other mental disorders, and other chronic non-communicable diseases and their risk factors. Information was gathered on sociodemographic characteristics; disability, dependency and frailty; use of health services; and characteristics of care and caregiver burden. The first assessment also included blood tests: complete blood count, blood glucose, kidney and liver function, lipid profile and ApoE4 genotype (a susceptibility marker). In 2007–2011, the second assessment was done of 2010 study subjects aged ≥65 years who were still alive. The study provides data on prevalence and incidence of dementia and its risk factors, and of related conditions that affect the health of older adults. It also contributes valuable experiences from field work and interactions with older adults and their families. Building on lessons learned, a third assessment to be done in 2016–2018 will incorporate a community intervention strategy to respond to diseases and conditions that predispose to dementia, frailty and dependency in older adults.

KEYWORDS Dementia, Alzheimer disease, chronic disease, aging, chronic illness, frailty, dependency, cohort studies, Cuba

INTRODUCTION Chronic non-communicable diseases are the leading cause of death worldwide, except in Sub-Saharan Africa. Nonetheless, one of these conditions, dementia, is the major contributor to disability-adjusted life years in people aged ≥60 years. Few epidemiological studies exist of the prevalence and impact of dementia and selected chronic diseases in older adults in Latin America.

OBJECTIVE Describe prevalence of dementia, other chronic vascular diseases and cardiovascular risk factors, as well as resulting disabilities and care needs generated in adults aged ≥65 years in Havana City and Matanzas provinces, Cuba.

METHODS The 10/66 study is a prospective longitudinal study involving a cohort of 3015 adults aged ≥65 years in municipalities of Havana City and Matanzas provinces, divided into two phases: a cross-sectional door-to-door study conducted in 2003–2006, and a follow-up and assessment phase in 2007–2010. This article reports findings from the first phase. Hypertension diagnosis was based on criteria from the International Society for Hypertension; diabetes mellitus on American Diabetes Association criteria; stroke according to WHO definitions; and dementia according to criteria of the American Psychiatric Society’s Diagnostic and Statistical Manual of Mental Disorders DSM-IV and the 10/66 International Dementia Research Group. Ischemic heart disease was defined by self-report of previous physician diagnosis. Study variables included age, sex, educational level, substance use (alcohol, tobacco) and dietary habits. A structured physical and neurological exam, including blood pressure measurement, was performed on all participants. Laboratory tests included complete blood count, fasting blood glucose, total cholesterol and lipoprotein fractions, triglycerides and apolipoprotein E genotype. Prevalence and standardized morbidity ratios (crude and adjusted) were calculated for chronic diseases studied with 95% confidence intervals, using a Poisson regression model and indirect standardization.

RESULTS The study assessed 2944 older adults (response rate 97.6%) and found high prevalence of vascular risk factors and of chronic non-communicable diseases: hypertension 73.0% (95% CI 71.4–74.7), diabetes mellitus 24.8% (95% CI 22.9–26.5), ischemic heart disease 14.1% (95% CI 12.9–15.4), dementia 10.8% (95% CI 9.7–12.0) and stroke 7.8% (95% CI 6.9–8.8). The majority of participants (85%) had more than one cardiovascular risk factor. The main cause of disability and dependency in the study population was dementia.

CONCLUSION The high prevalence of chronic diseases observed in the elderly—with the consequent morbidity, disability and dependency—highlights the need for prevention, early diagnosis and risk factor control, particularly given the demographic and epidemiologic transition faced by Cuba and other developing countries.

KEYWORDS Dementia, chronic disease, cardiovascular diseases, heart disease, stroke, diabetes mellitus, disability, hypertension, aging, prevalence, epidemiology, Cuba