Abstract

This article aims to estimate the prevalence of cognitive impairment and analyze its association with blood pressure control in elderly hypertensive individuals. Cross-sectional study of 383 elderly hypertensive individuals in the state of Piauí, Brazil. The authors collected sociodemographic and clinical data, performed blood pressure measurement, and assessed cognitive function using the Montreal Cognitive Assessment (MoCA) test. Poisson regression with robust variance was used. Overall prevalence of cognitive impairment was 74.4%, higher in the age group 80 years and over and among older persons with less schooling. Prevalence of uncontrolled blood pressure was 61.6%, with a higher proportion in the elderly with cognitive impairment. An association was observed between cognitive impairment and uncontrolled blood pressure (aPR: 3.98; 95%CI = 2.51-6.33). The significant association between cognitive function and blood pressure control suggest that cognitive impairment is an important risk factor for uncontrolled blood pressure in older persons. The inclusion of screening measures for possible cognitive deficits may be useful for better monitoring blood pressure levels among elderly hypertensive individuals.

Key words:
Elderly; Cognition; Aging; Hypertension; Family Health Strategy Primary healthcare

Introduction

High blood pressure (HBP) is a chronic noncommunicable disease, considered one of the leading mortality risks in the world¹1 Mills KT, Bundy JD, Kelly TN, Reed JE, Kearney PM, Reynolds K, Chen J, He J. Global disparities of hypertension prevalence and control: a systematic analysis of population-based studies from 90 countries. Circulation 2016; 134(6):441-50.. Prevalence of hypertension increases significantly with age, and HBP is more prevalent among the elderly than in the young and middle-aged population²2 Forouzanfar MH, Liu P, Roth GA, Ng M, Biryukov S, Marczak L, Alexander L, Estep K, Hassen Abate K, Akinyemiju TF, Ali R, Alvis-Guzman N, Azzopardi P, Banerjee A, Bärnighausen T, Basu A, Bekele T, Bennett DA, Biadgilign S, Catalá-López F, Feigin VL, Fernandes JC, Fischer F, Gebru AA, Gona P, Gupta R, Hankey GJ, Jonas JB, Judd SE, Khang YH, Khosravi A, Kim YJ, Kimokoti RW, Kokubo Y, Kolte D, Lopez A, Lotufo PA, Malekzadeh R, Melaku YA, Mensah GA, Misganaw A, Mokdad AH, Moran AE, Nawaz H, Neal B, Ngalesoni FN, Ohkubo T, Pourmalek F, Rafay A, Rai RK, Rojas-Rueda D, Sampson UK, Santos IS, Sawhney M, Schutte AE, Sepanlou SG, Shifa GT, Shiue I, Tedla BA, Thrift AG, Tonelli M, Truelsen T, Tsilimparis N, Ukwaja KN, Uthman OA, Vasankari T, Venketasubramanian N, Vlassov VV, Vos T, Westerman R, Yan LL, Yano Y, Yonemoto N, Zaki ME, Murray CJ. Global burden of hypertension and systolic blood pressure of at least 110 to 115 mm Hg, 1990-2015. JAMA 2017; 317(2):165-182.. In Brazil, HBP affect 36 million adults (32.5%) and more than 60% of the elderly, contributing directly or indirectly to 50% of cardiovascular deaths³3 Scala LC, Magalhães LB, Machado A. Epidemiologia da hipertensão arterial sistêmica. In: Moreira SM, Paola AV. In: Moreira MCV, Montenegro ST, De Paola AAV, organizadores. Livro Texto da Sociedade Brasileira de Cardiologia. 2ª. ed. São Paulo: Manole; 2015. p. 780-785..

Although HBP is a major public health problem, leading to high costs for the health system due to complications, it still displays low control rates, thus increasing the risk of cardiovascular morbidity and mortality ⁴4 Yang F, Qian D, Hu D. Prevalence, awareness, treatment, and control of hypertension in the older population: results from the multiple national studies on ageing. J Am Soc Hypertens 2016; 10(2):140-148..

A recent study of hypertensive individuals 60 years or older found that 58.8% of participants were aware of their clinical condition, and that 96.5% of these were in treatment. Among treated participants, only 24.5% had their blood pressure (BP) adequately controlled, thus emphasizing the importance of strengthening primary care⁵5 Gupta S, Kumar R, Kalaivani M, Nongkynrih B, Kant S, Gupta SK. Prevalence, awareness, treatment, and control of diabetes and hypertension among elderly persons in a rural area of Ballabgarh, Haryana. J Family Med Prim Care 2020; 9(2):777-782.. Brazilian studies have also shown low levels of blood pressure control in the elderly, varying from 27% to 50.8%⁶6 Pinho NA, Pierin AMG. O controle da hipertensão arterial em publicações brasileiras. Arq Bras Cardiol 2013; 101(3):e65-e73.^,77 Sousa ALL, Batista SR, Sousa AC, Pacheco JAS, Vitorino PVO, Pagotto V. Prevalência, tratamento e controle da hipertensão arterial em idosos de uma capital brasileira. Arq Bras Cardiol 2019; 112(3):271-278..

Adequate control of BP levels is related to various factors such as sociodemographic characteristics (sex, age, schooling, income), health behavior (sedentary lifestyle), and treatment adherence⁸8 Luz ALA, Silva-Costa A, Griep RH. Pressão arterial não controlada entre pessoas idosas hipertensas assistidas pela Estratégia Saúde da Família. Rev Bras Geriatr Gerontol 2020; 23(4):e200211.. In addition, cognitive impairment (CI) has been described as an important risk factor associated with inadequate blood pressure control⁹9 Piotrowicz K, Prejbisz A, Klocek M, Topór-Madry R, Szczepaniak P, Kawecka-Jaszcz K, Narkiewicz K, Grodzicki T, Januszewicz A, Gasowski J. Subclinical mood and cognition impairments and blood pressure control in a large cohort of elderly hypertensives. J Am Med Dir Assoc 2016; 17(9):864.e17-e22.. CI poses a risk for daily activities of selfcare¹⁰10 Petersen RC, Caracciolo B, Brayne C, Gauthier S, Jelic V, Fratiglioni L. Mild cognitive impairment: a concept in evolution. J Intern Med 2014; 275(3):214-228., which are indispensable for maintaining BP within adequate levels. Since memory (the capacity to retrieve information) influences various aspects of life, and communication is the key element for wellbeing and survival¹¹11 Castro MS, Fuchs FD, Santos MC, Maximiliano P, Gus M, Moreira LB, Ferreira MB. Pharmaceutical care program for patients with uncontrolled hypertension. Report of a double-blind clinical trial with ambulatory blood pressure monitoring. Am J Hypertens 2006; 19(5):528-533., its impairment can compromise adherence to medication and selfcare and thus BP control in hypertensive patients.

In this context, although some studies have shown that cognitive deficit is associated with uncontrolled BP⁹9 Piotrowicz K, Prejbisz A, Klocek M, Topór-Madry R, Szczepaniak P, Kawecka-Jaszcz K, Narkiewicz K, Grodzicki T, Januszewicz A, Gasowski J. Subclinical mood and cognition impairments and blood pressure control in a large cohort of elderly hypertensives. J Am Med Dir Assoc 2016; 17(9):864.e17-e22.^,1212 Vinyoles E, De la Figuera M, Gonzalez-Segura D. Cognitive function and blood pressure control in hypertensive patients over 60 years of age: COGNIPRES study. Curr Med Res Opin 2008; 24(12):3331-3339., there is still little information on the association between CI and BP control, especially in the elderly population. The current study thus aimed to estimate the prevalence of CI and analyze its association with BP control in a sample of elderly hypertensive Brazilians.

Method

Study design, population, and sample

This cross-sectional epidemiological study was conducted in the city of Picos, Piauí, Brazil, from June to November 2019. The municipality lies in the central-south region of the state of Piauí, 314 kilometers from the state capital Teresina, and has 36 family health teams (25 in the urban area and 11 in the rural area), with 100% population coverage by the Family Health Strategy.

Inclusion criteria for participation in the study were the following: age 60 years or older, coverage by the Family Health Strategy in the urban area of Picos, medical diagnosis of HBP, and use of antihypertensive medication. Exclusion criteria were elderly with prior diagnosis of dementia, history of stroke, severe visual and/or hearing impairment preventing cognitive assessment, psychiatric disorders, and institutionalized or hospitalized elderly.

To obtain the total number of elderly persons with HBP in the municipality of Picos, a list was first organized by the Family Health Strategy with the names and contact information of the nurses (team coordinators) and their respective community health workers. Next, the total number of 3,524 elderly with HBP was obtained from the Family Health Strategy, based on a survey of all the Family Health Strategy teams in the municipality (100% coverage).

Estimation of the sample size used the following parameters: estimated prevalence of 50%⁸8 Luz ALA, Silva-Costa A, Griep RH. Pressão arterial não controlada entre pessoas idosas hipertensas assistidas pela Estratégia Saúde da Família. Rev Bras Geriatr Gerontol 2020; 23(4):e200211. to obtain the largest sample size, population size of 3,524 elderly with HBP monitored by the Family Health Strategy in the urban area, 5% estimation error, 95% confidence interval, and an additional 10% for possible losses and refusals. The estimated minimum sample was 382 elderly hypertensive individuals. Participants were selected by random sampling with distribution proportional to the sample size among elderly hypertensive individuals registered with each Family Health Strategy team.

After losses and refusals, the study´s final sample consisted of 383 elderly persons. Losses were defined as participants not located after three visits, change of address, or death. Contact with the selected elderly was done by the respective community health workers under the reference Family Health Strategy, who explained the study´s objectives and participation to the elderly. All participants signed a free and informed consent form.

Data collection

Data collection used a face-to-face interview through a previously scheduled home visit. Data were collected by a trained team, consisting of 39 interviewers (undergraduate nursing students) under the supervision of two registered nurses.

The questionnaires were carefully drafted, pretested, and accompanied by a detailed instructions manual on the questions and orientation on how to proceed in case of doubts. Data quality control was reinforced by regular meetings with all interviewers and supervisors.

The interviewers were properly trained and certified, and the same care was maintained weekly when the questionnaires were turned in, with careful review by the data collection team supervisors.

Since the fieldwork involved participation by a large number of interviewers and was thus subject to wide margin of error, all procedures were accompanied by an instruction manual for proper completion of the questionnaire, standardization of anthropometric assessment techniques, and blood pressure measurement. Interviewers and supervisors also participated in regular meetings to clarify doubts concerning the data collection instrument and the approach to the elderly individuals.

The following variables were included in the study:

Cognitive function was assessed with the Montreal Cognitive Assessment test (MoCA), developed specifically for screening milder forms of CI and taking approximately ten minutes to administer¹³13 Nasreddine ZS, Phillips NA, Bédirian V, Charbonneau S, Whitehead V, Collin I, Cummings JL, Chertkow H. The Montreal Cognitive Assessment, MoCA: a brief screening tool for mild cognitive impairment. J Am Geriatr Soc 2005; 53(4):695-659.. The domains comprising the MoCA are visuospatial skills; executive functions, attention and concentration, language, memory, visuoconstructional abilities, calculation, abstraction, and orientation. The maximum score on the MoCA is 30 points, and higher scores reflect better performance¹³13 Nasreddine ZS, Phillips NA, Bédirian V, Charbonneau S, Whitehead V, Collin I, Cummings JL, Chertkow H. The Montreal Cognitive Assessment, MoCA: a brief screening tool for mild cognitive impairment. J Am Geriatr Soc 2005; 53(4):695-659.. The current study used a cutoff of ≤ 24 points for presence of CI, based on sensitivity and specificity of 81% and 77%, respectively, in screening CI in elderly Brazilians¹⁴14 Memória CM, Yassuda MS, Nakano EY, Forlenza OV. Brief screening for mild cognitive impairment: validation of the Brazilian version of the Montreal cognitive assessment. Int J Geriatr Psychiatry 2013; 28(1):34-40..

The study´s dependent variable was uncontrolled BP, defined as systolic blood pressure (SBP) ≥ 140 mmHg and diastolic blood pressure (DBP) ≥ 90 mmHg. BP measurements were performed with automatic BP monitors (OMROM model HEM-7130), properly calibrated, with an OMROM universal HEM-RML31 cuff (22-42 cm), appropriate for arm circumference, according to the protocol of the 7^th Brazilian Guidelines on Systemic Arterial Hypertension³3 Scala LC, Magalhães LB, Machado A. Epidemiologia da hipertensão arterial sistêmica. In: Moreira SM, Paola AV. In: Moreira MCV, Montenegro ST, De Paola AAV, organizadores. Livro Texto da Sociedade Brasileira de Cardiologia. 2ª. ed. São Paulo: Manole; 2015. p. 780-785..

For BP measurement, the elderly individual remained seated in a quiet setting, arm resting on the table at the level the heart, having rested previously for at least 5 minutes, besides absence of effort or physical exercise, alcohol use, or smoking in the 30 minutes prior to the measurements, and with an empty bladder.

Three BP measurements were taken on the left arm at 2-minute intervals, and the average of the last two measurements was recorded as final. Arm circumference was measured at the midpoint between the left shoulder and left elbow, at the level of the heart (fourth intercostal space) with the patient seated for the BP measurement.

All participants were asked about the medication they were taking for hypertension and to show the prescriptions and/or medications at the time of the interview.

Adherence to antihypertensive medication was assessed with the Brief Medication Questionnaire (BMQ), an instrument validated for the hypertensive population¹⁵15 Ben AJ, Neumann CR, Mengue SS. Teste de Morisky-Green e Brief Medication Questionnaire para avaliar adesão a medicamentos. Rev Saude Publica 2012; 46(2):279-289., consisting of three domains that identify barriers to adherence, beliefs, and recall in relation to drug treatment. The BMQ was dichotomized, and nonadherence was defined as a score ≥ 2 points.

Nutritional status was assessed by body mass index (BMI), obtained by dividing weight in kilograms by height in meters squared, with the Lipschitz classification¹⁶16 Lipschitz DA. Screening for nutricional status in the elderly. Prim Care 1994; 21(1):55-67.: underweight (BMI < 22.0 kg/m²), normal weight (22.0 ≥ BMI < 27.0 kg/m²), and excess weight (BMI ≥ 27.0 kg/m²), with specific cutoff points for the elderly.

Weight (kg) was measured with a portable digital scale (Kikos ISON brand), with a capacity of 150 kg and precision of 0.1 kg, with an automatic display activated by the participant´s feet at the time of weighing, positioned in the center of the scale, barefoot, and wearing light clothing. Height (cm) was measured with an inelastic tape measure attached to the wall, with a maximum height of 2 m and precision of 1mm, with the participant standing erect, barefoot, heels together, and arms hanging by the sides.

Statistical analysis

A descriptive analysis was performed (absolute frequencies and percentages, means and standard deviations [SD], medians and interquartile ranges [IQR]) to present the distribution of the sociodemographic data, clinical characteristics, and BP control. Shapiro-Wilk test was used to assess data normality. Due to the nonnormal distribution of the MoCA domains, the cognitive performance in each MoCA domain between the groups with controlled and uncontrolled BP was compared with the Mann-Whitney test. Pearson chi-square and linear trend were used to test associations between categorical variables.

Poisson regression with robust variance was used to analyze the association between CI and blood pressure control. Variables that presented p-value < 0.20 in the crude model (sex, age group, schooling, BMI, self-rated health, treatment adherence, and time since last appointment) were included in the multivariate regression model.

The model was adjusted for possible confounding factors (control variables), based on the literature. Model 1 included the sociodemographic variables (sex, age group, and schooling); in model 2, variables related to health status and HBP were added (BMI, self-rated health, and treatment adherence); and model 3 also included variables on use of health services (time since last appointment).

Adjusted analysis used stepwise variable selection with backward elimination. Sex, age, and schooling were considered control variables and were thus present in all the models. In the adjusted analysis, the final model only retained the variables with p-value < 0.05.

Data were keyed in twice, corrected, and their consistency was assessed with Epi Info version 3.4.3. All statistical analyses used the R software version 3.6.1, and the results were expressed by prevalence ratios (PR) and their respective 95% confidence intervals (CI).

Ethical aspects

The study was approved by the Institutional Review Board of the Sergio Arouca National School of Public Health (ENSP-FIOCRUZ) under review no. 3.307.403 on May 12, 2019, complying with the ethical principles in Resolution 466/2012 of the Brazilian National Health Council.

Results

Most of the elderly hypertensive individuals were females (64.2%), 60 to 69 years of age (46.5%). The majority reported time since last appointment greater than three months (54.3%) and did not participate in hypertension support groups in the health unit (77.5%) (Table 1).

Prevalence of CI increased linearly with age and inversely to schooling. Prevalence of uncontrolled BP was 70.8% in men and 56.7% in women. Among elderly with “very bad/bad” self-rated health, prevalence of uncontrolled BP was higher (78.9%) than in elderly with “very good/good” self-rated health (65.8%), as shown in Table 1.

Prevalence of uncontrolled BP was 61.6%. Elderly with CI showed higher mean SBP (144.3 [SD = 16.50] mmHg) and DBP (85.66 [SD = 10.12] mmHg) than elderly without CI (SBP: 124.9 [SD = 14.43] mmHg; DBP: 77.38 [SD = 9.40] mmHg; p < 0.001). Cognitive impairment was seen in most of the participants (74.4%), and 77.5% of these presented uncontrolled BP (p < 0.001) (data not shown in the Table).

Elderly hypertensive individuals with controlled BP scored higher on performance in most of the cognitive domains, except for visuospatial/executive function, compared to elderly with uncontrolled BP. Among elderly hypertensive individuals with controlled BP, median score on the MoCA was higher (25; IQR = 19-25 points) than in those with uncontrolled BP (20; IQR = 17-23 points), as shown in Table 2.

Crude regression analysis showed that elderly hypertensive individuals with CI presented 5.07 times higher prevalence (95%CI = 3.17-8.10) of uncontrolled BP compared to elderly without CI. Cognitive impairment remained strongly associated with uncontrolled BP (RP = 5.13; 95%CI = 3.25-8.09) after adjusting for confounding factors (Table 3).

Discussion

This study, as in the few international studies identified in the literature⁹9 Piotrowicz K, Prejbisz A, Klocek M, Topór-Madry R, Szczepaniak P, Kawecka-Jaszcz K, Narkiewicz K, Grodzicki T, Januszewicz A, Gasowski J. Subclinical mood and cognition impairments and blood pressure control in a large cohort of elderly hypertensives. J Am Med Dir Assoc 2016; 17(9):864.e17-e22.^,1212 Vinyoles E, De la Figuera M, Gonzalez-Segura D. Cognitive function and blood pressure control in hypertensive patients over 60 years of age: COGNIPRES study. Curr Med Res Opin 2008; 24(12):3331-3339., indicates that cognitive impairment is heavily associated with uncontrolled BP in the elderly. The study expands the knowledge on hypertension, particularly related to blood pressure control in elderly persons, and the results support the understanding of cognitive deficit as an important factor associated with uncontrolled BP.

Populations are aging worldwide, and HBP is one of the most common chronic noncommunicable conditions in the elderly¹⁷17 World Health Organization (WHO). Global Status Report on noncommunicable diseases 2014. Geneva: WHO; 2014., acknowledged as a risk factor for cardiovascular diseases¹⁸18 Kintscher U. The burden of hypertension. Euro intervention 2013; 9 (Suppl. R): R12-R15.. Given this scenario, there is evidence that HBP can play a role in cognitive dysfunction, increasing the risk of related diseases such as Alzheimer´s disease and vascular dementia¹⁹19 Akinyemi RO, Mukaetova-Ladinska EB, Attems J, Ihara M, Kalaria RN. Vascular risk factors and neurodegeneration in ageing related dementias: Alzheimer's disease and vascular dementia. Curr Alzheimer Res 2013; 10(6):642-653..

A study by Piotrowicz et al.⁹9 Piotrowicz K, Prejbisz A, Klocek M, Topór-Madry R, Szczepaniak P, Kawecka-Jaszcz K, Narkiewicz K, Grodzicki T, Januszewicz A, Gasowski J. Subclinical mood and cognition impairments and blood pressure control in a large cohort of elderly hypertensives. J Am Med Dir Assoc 2016; 17(9):864.e17-e22. (2016) in 1,988 elderly hypertensive individuals in use of antihypertensive medication for at least one year showed that CI was associated with a 15% higher risk of inadequate BP control. The authors highlighted the high impact of these findings for patients´ health and the importance of geriatric assessment, including instruments to assess cognition, as alternatives for screening individuals with increased risk of low adherence to drug treatment and to help improve the low rates of BP control in the elderly population. The authors further emphasized that patients with CI should be monitored regularly for their mental health status. Caregivers or family members may also need orientation to supervise the patients’ antihypertensive treatment or all drug treatments in the case of cognitive deficit, however subtle.

The study’s results showed that elderly hypertensive individuals with uncontrolled BP performed worse on their total cognitive score and in most cognitive domains. The findings are consistent with studies that identified low cognitive performance in elderly hypertensive individuals or with increased BP²¹21 Muela HC, Costa-Hong VA, Yassuda MS, Moraes NC, Memória CM, Machado MF, Macedo TA, Shu EB, Massaro AR, Nitrini R, Mansur AJ, Bortolotto LA. Hypertension severity is associated with impaired cognitive performance. J Am Heart Assoc 2017; 6(1):e004579.^,2222 Fitri FI, Rambe AS, (2018) Correlation between hypertension and cognitive function in elderly. IOP Conf Ser: Earth Environ Sci 2018; 125:012177..

Contrary to other studies that found significant differences for all cognitive domains of MoCa²¹21 Muela HC, Costa-Hong VA, Yassuda MS, Moraes NC, Memória CM, Machado MF, Macedo TA, Shu EB, Massaro AR, Nitrini R, Mansur AJ, Bortolotto LA. Hypertension severity is associated with impaired cognitive performance. J Am Heart Assoc 2017; 6(1):e004579.^,2222 Fitri FI, Rambe AS, (2018) Correlation between hypertension and cognitive function in elderly. IOP Conf Ser: Earth Environ Sci 2018; 125:012177., the current study did not show a statistically significant difference in scores in the visuospatial and executive domains between participants with controlled and uncontrolled BP.

Performance in cognitive skills is dependent on executive functions, and their decline can compromise planning capacity, mental flexibility, and performance of strategic actions²³23 Goldman-Rakic PS. Cellular basis of working memory. Neuron 1995; 14(3):477-485.. These are important functions for decision-making and selfcare. Evidence shows that cognitive alterations can appear early and may go unnoticed²⁴24 Barone P, Aarsland D, Burn D, Emre M, Kulisevsky J, Weintraub D. Cognitive impairment in nondemented Parkinson's disease. Mov Disord 2011; 26(14):2483-2495., especially in memory and executive functions. Executive function also involves multiple brain processes, and the cognitive domain is therefore more difficult to assess and with greater heterogeneity in the ways studies measure it²⁵25 Iadecola C, Yaffe K, Biller J, Bratzke LC, Faraci FM, Gorelick PB, Gulati M, Kamel H, Knopman DS, Launer LJ, Saczynski JS, Seshadri S, Zeki Al Hazzouri A, American Heart Association Council on Hypertension, Council on Clinical Cardiology, Council on Cardiovascular Disease in the Young, Council on Cardiovascular and Stroke Nursing, Council on Quality of Care and Outcomes Research, Stroke Council. Impact of hypertension on cognitive function: a scientific statement from the American Heart Association. Hypertension 2016; 68(6):e67-e94..

Some additional factors may explain the heterogeneity in the results on impairment of visuospatial and executive skills and their relationship to blood pressure control, such as time and severity of the disease, type of medication for HBP, and SBP levels, especially among the older elderly individuals.

There is little information on cognitive function and BP control in middle-income countries. In Brazil, the epidemiological data are scarce on the influence of CI on blood pressure control, thus limiting the management of patient care and action in evidence-based information programs to allow better management of HBP.

The current study´s results have important clinical implications because elderly hypertensive individuals with CI can have their selfcare and activities of daily living compromised. CI can lead to unintentional errors with dosage or amounts of medications, forgetting the days, hours, or types of medications used, thereby interrupting treatment continuity and compromising adequate control of BP levels.

Screening instruments have their limitations. Although findings in the literature suggest that MoCA is a rapid and precise screening tool for the identification and diagnosis of cognitive impairment, when compared to other instruments such as the Mini-Mental State Examination²¹21 Muela HC, Costa-Hong VA, Yassuda MS, Moraes NC, Memória CM, Machado MF, Macedo TA, Shu EB, Massaro AR, Nitrini R, Mansur AJ, Bortolotto LA. Hypertension severity is associated with impaired cognitive performance. J Am Heart Assoc 2017; 6(1):e004579., a test battery may be more effective in the identification of deficits in specific cognitive domains.

Many studies have been performed for validation of the MoCA in diverse populations, and various cutoff points have been proposed²⁶26 Ng A, Chew I, Narasimhalu K, Kandiah N. Effectiveness of Montreal Cognitive Assessment for the diagnosis of mild cognitive impairment and mild Alzheimer's disease in Singapore. Singapore Med J. 2013; 54(11):616-619.. As in our study, using a cutoff in MoCA of 25 points and correction of 1 point in patients with less than 12 years of schooling, Muela et al.²¹21 Muela HC, Costa-Hong VA, Yassuda MS, Moraes NC, Memória CM, Machado MF, Macedo TA, Shu EB, Massaro AR, Nitrini R, Mansur AJ, Bortolotto LA. Hypertension severity is associated with impaired cognitive performance. J Am Heart Assoc 2017; 6(1):e004579. (2017) conducted a sub-analysis of cognitive performance in patients with high levels of education (≥ 9 years of schooling), and even in this subgroup of patients in whom schooling might have a protective effect, they found that worse cognitive performance was associated with severity of BP levels.

The low schooling observed in most of the elderly individuals in the current study is frequently found in current research²⁷27 Rosa TSM, Filha VAVS, Moraes AB. Prevalência e fatores associados ao prejuízo cognitivo em idosos de instituições filantrópicas: um estudo descritivo. Cien Saude Colet 2018; 23(11):3757-3765.. The number of years of schooling, considered a neuronal protective factor, is also a diagnostic confounding element, since individuals´ performance on cognitive assessment instruments is heavily influenced by schooling²⁸28 Santos CC, Ortega AC. O papel dos esquemas na memória de idosas saudáveis. Psicol Estud 2012; 17(2):267-276..

Thus, the education variable is complex and individual and may be reflected in adulthood and contribute to intellectual decline in old age²⁹29 Gurian MBF, De Oliveira RC, Laprega MR, Rodrigues Júnior AL. Rastreamento da função cognitiva de idosos não-institucionalizados. Rev Bras Geriatr Gerontol 2012; 15(2):275-284.. Differences in the proposed cutoff points and the influence of schooling in many studies highlight the importance of conducting validations of MoCA in specific populations, to maintain its efficacy as a screening tool.

The study’s strengths and limitations

The study provides evidence that cognitive impairment can be a key element for understanding inadequate blood pressure control in elderly hypertensive individuals, expanding the existing literature on this topic, which has received relatively little research attention. In addition, the adjustment for possible confounding factors such as age to avoid overestimating or underestimating the results was important for understanding the association between CI and uncontrolled BP.

However, the study presents some limitations when interpreting the results. The cross-sectional design does not allow establishing a causal relationship between CI and uncontrolled BP. There was also a possible reverse causality bias, which limits inferences on the association’s direction (CI influencing BP control).

The sample of elderly restricted to only one municipality in the interior of Brazil limits the results’ generalization to other populations. Future studies are thus needed for a more comprehensive and in-depth approach to the topic to elucidate the associations.

Measurement of BP on a single visit also hinders knowing whether the BP levels were stable at other moments and may thus not reflect the individuals’ usual BP levels. In addition, although we used the cutoff point proposed by Memória et al. (2013) for the Brazilian population, the low schooling in most of the participants may have caused difficulties in understanding the MoCA content.

Conclusion

The significant association between cognitive function and blood pressure control in elderly persons with hypertension in the Family Health Strategy in Picos, Piauí, Brazil, indicates that the inclusion of screening measures for possible cognitive deficits may be important allies in the assessment of high blood pressure levels in hypertensive elderly persons in primary healthcare.

The findings emphasizing the high prevalence of CI and uncontrolled BP can support studies that assess the possible effects of CI on BP levels in elderly hypertensive individuals. The results can also help improve the approach to and care for this population, helping plan interventions according to individual and contextual characteristics and with the assistance of elderly persons´ caregivers to determine better control of high blood pressure and thereby prevent future complications.

References

Publication Dates

History