Elsevier

Neurobiology of Aging

Volume 33, Issue 4, April 2012, Pages 829.e21-829.e28
Neurobiology of Aging

Abstract of online article
Sodium intake and physical activity impact cognitive maintenance in older adults: the NuAge Study

https://doi.org/10.1016/j.neurobiolaging.2011.07.004Get rights and content

Abstract

This study examines the association between sodium intake and its interaction with physical activity on cognitive function over 3 years in older adults residing in Québec, Canada. We analyzed a subgroup from the NuAge cohort (aged 67–84 years) with nutrient intake data, including sodium, from a food frequency questionnaire administered at baseline. Baseline physical activity was assessed using the Physical Activity Scale for the Elderly (PASE; high-low). Modified Mini Mental State Examination (3MS) was administered at baseline and annually for 3 additional years. Controlling for age, sex, education, waist circumference, diabetes, and dietary intakes, analyses showed an association between sodium intake and cognitive change over time in the low PASE group only. Specifically, in the low PASE group, elders in the low sodium intake tertile displayed better cognitive performance over time (mean decline in 3MS over years: mean [M] = −0.57, standard error [SE] = 0.002) compared with the highest (M = −1.72, SE = 0.01) and mid sodium intake (M = −2.07, SE = 0.01) groups. This finding may have significant public health implications, emphasizing the importance of addressing multiple lifestyle factors rather than a single domain effect on brain health.

Introduction

Sodium intake is of great interest due to its association with blood pressure regulation and heart disease. Heart disease is a major cause of mortality and disability, especially in individuals 60 years and older (Mathers and Loncar, 2006, Woloshin et al., 2008). Animal and human studies have shown that high sodium intake is associated with increased blood pressure and cardiovascular disease (Cook, 2008, Denton et al., 1995, Stamler, 1997). Based on robust findings, national and international groups, including the World Health Organization (WHO), have set out to promote reductions in sodium intake at the population level to reduce the incidence of cardiovascular disease (Institute of Medicine, 2010; Minister of Health, 2007; WHO, 2007).

While lowering sodium consumption is associated with reduced blood pressure and risk of heart disease (Cutler, 1991), less is known about the effect of sodium intake on cognitive function. With population aging, there is both a rise in cardiovascular events and a projected expansion of dementia cases in late life (Brookmeyer et al., 1998). Furthermore, risk factors for cardiovascular disease, including hypertension, are also common risk factors for dementia (Grodstein, 2007, Purnell et al., 2009). Thus, it may be postulated that sodium intake not only impacts heart health, but brain health as well.

Hypertension at midlife is reportedly associated with worse cognitive function in late life (Kloppenborg et al., 2008). Studies show that hypertension may mediate adverse effects on brain function through a number of mechanisms, including altered cerebral endothelium, vascular remodeling, impaired cerebral autoregulation, cerebral microbleeds, white matter hyperintensities (WMH), unrecognized lacunar infarcts, and Alzheimer-like changes such as amyloid angiopathy and cerebral atrophy (Manolio et al., 2003). However, according to a Cochrane systematic review, there is no convincing evidence that lowering blood pressure in older adults prevents the development of cognitive impairment or dementia (McGuinness et al., 2009).

Although there is a paucity of research that examines the impact of sodium intake on brain health, research has increasingly examined the link between diet and cognitive function in late life. Research shows that adherence to a Mediterranean diet, which is high in fruits and vegetables, reduces the rate of cognitive decline with age (Tangney et al., 2011). Furthermore, dietary fat intake has been found to associate with cognitive function. Specifically, fatty fish and omega-3 fatty acids are associated with good cognitive health, whereas saturated fat intake is associated with increased risk of impaired cognitive function (Kalmijn et al., 1997, Kalmijn et al., 2004). Specific nutrients, including vitamins D, E, and B-complex, have been examined in relation to cognitive function in late life (Annweiler et al., 2010, Morris et al., 2007, Usoro and Mousa, 2010). In a small cross-sectional study that assessed the relationship between nutrient intake and cognitive performance in people at risk of dementia, it was found that cholesterol and sodium intakes differentiated middle-aged adults who scored within the normal range on a test of global cognitive function compared with those who scored below the normal cutoff (Salerno-Kennedy and Cashman, 2007).

In addition to reductions in sodium intake, research has shown that physical activity may improve both cardiovascular and cognitive health (Brown et al., 2010, Eskes et al., 2010, Jedrziewski et al., 2010, Kelley and Kelley, 2008, Kramer et al., 2006, Maiorana et al., 2011). Furthermore, an additive effect of reduction in sodium intake and physical exercise has been reported in hypertensive adults. In a randomized controlled trial that assessed the effect of a reduced sodium diet (Dietary Approaches to Stop Hypertension; DASH) and exercise program on neurocognitive function in sedentary, overweight hypertensive adults, it was found that individuals in the combined DASH plus exercise group showed the most pronounced improvement in cognitive function, compared with individuals in the DASH diet alone. It was also reported that the greatest neurocognitive improvement was observed in those with the highest level of systolic blood pressure (Smith et al., 2010).

The present study assessed the association between sodium intake and global cognitive function over 3 years of follow-up in older adults. Specifically, the present study examined 3 questions: (1) is there a direct association between sodium intake and cognitive function?; (2) does hypertension moderate the association between sodium intake and cognitive function?; and (3) is there an additive impact of sodium intake and physical activity on cognitive function?. To this end, it is hypothesized that higher sodium intake will associate with lower cognitive function over time and this relationship will be moderated by the presence of hypertension. Further, based on the DASH report (Smith et al., 2010), it is hypothesized that low sodium intake and high physical activity will impose an additive positive effect on cognitive function in older adults.

Section snippets

Study Population

We examined a subgroup of participants from the Québec Longitudinal Study on Nutrition and Successful Aging (NuAge Study), a 5-year prospective study of 1793 cognitively intact and functionally independent elders aged 67–84 years upon recruitment, described in more detail elsewhere (Bouchard et al., 2007, Gaudreau et al., 2007). Participants in the original cohort were randomly selected from the Québec Medicare database and were stratified by age and sex. They were tested annually at the

Baseline characteristics

Among 1262 participants, 420 fell into the low sodium intake tertile group (median [M] = 1791 mg/day, standard error [SE] = 15), 421 fell into the mid tertile group (M = 2648 mg/day, SE = 11) and 421 fell into the high tertile group (M = 3919 mg/day, SE = 36) (for median and range values, see Table 1). Tertile groups differed on total energy, cholesterol, and calcium intake, and total C-HEI score (p < 0.001). Baseline characteristics including sex, waist circumference, physical activity, and

Discussion

Worldwide sodium reduction strategies are being recommended with a focus on reducing heart disease. It is estimated that a reduction in sodium intake may result in major annual savings in medical care costs and physician visits related to hypertension (Joffres et al., 2007). Sodium intake reduction has been reported to be especially beneficial in older populations (Alam and Johnson, 1999, Cappuccio et al., 1997). This study suggests that sodium intake reduction, especially in low physical

Disclosure statement

None of the authors report any conflict of interest.

The protocol was approved by the REB of the institutions involved in the study: Institut Universitaire de Gériatrie de Montréal and the Institut Universitaire de Gériatrie de Sherbrooke. All participants signed an informed consent approved by the ethics committee at each institution.

Acknowledgements

We thank other members of the NuAge and NutCog groups for enabling this study through the development of the infrastructure and providing the essential databases. We also thank Katherine Gray-Donald and Pierrette Gaudreau for their insightful comments on the manuscript.

The NuAge Study is supported by CIHR MOP-62842. NutCog is supported by CIHR MOP-81217. A.J.F. is supported by a Canadian Institute of Health Research Fellowship.

References (51)

  • I. Skoog et al.

    15-year longitudinal study of blood pressure and dementia

    Lancet

    (1996)
  • J. Stamler

    The INTERSALT Study: background, methods, findings, and implications

    Am. J. Clin. Nutr

    (1997)
  • C.C. Tangney et al.

    Adherence to a Mediterranean-type dietary pattern and cognitive decline in a community population

    Am. J. Clin. Nutr

    (2011)
  • R.A. Washburn et al.

    The physical activity scale for the elderly (PASE): evidence for validity

    J. Clin. Epidemiol

    (1999)
  • R.A. Washburn et al.

    The Physical Activity Scale for the Elderly (PASE): development and evaluation

    J. Clin. Epidemiol

    (1993)
  • J.A. Yesavage et al.

    Development and validation of a geriatric depression screening scale: a preliminary report

    J. Psychiatr. Res

    (1982)
  • S. Alam et al.

    A meta-analysis of randomised controlled trials (RCT) among healthy normotensive and essential hypertensive elderly patients to determine the effect of high salt (NaCl) diet of blood pressure

    J. Hum. Hypertens

    (1999)
  • C. Annweiler et al.

    Dietary intake of vitamin D and cognition in older women: a large population-based study

    Neurology

    (2010)
  • G. Block et al.

    A data-based approach to diet questionnaire design and testing

    Am. J. Epidemiol

    (1986)
  • D.R. Bouchard et al.

    Fat mass but not fat-free mass is related to physical capacity in well-functioning older individuals: nutrition as a determinant of successful aging (NuAge)—the Quebec Longitudinal Study

    J. Gerontol. A Biol. Sci. Med. Sci

    (2007)
  • B.C. Bowen et al.

    MR signal abnormalities in memory disorder and dementia

    AJR Am. J. Reontgenol

    (1990)
  • R. Brookmeyer et al.

    Projections of Alzheimer's disease in the United States and the public health impact of delaying disease onset

    Am. J. Public Health

    (1998)
  • N.R. Cook

    Salt intake, blood pressure and clinical outcomes

    Curr. Opin. Nephrol. Hypertens

    (2008)
  • D. Denton et al.

    The effect of increased salt intake on blood pressure of chimpanzees

    Nat. Med

    (1995)
  • G.A. Eskes et al.

    Contribution of physical fitness, cerebrovascular reserve and cognitive stimulation to cognitive function in post-menopausal women

    Front. Aging Neurosci

    (2010)
  • Cited by (57)

    • Association of dietary sodium, potassium, sodium/potassium, and salt with objective and subjective cognitive function among the elderly in China: A prospective cohort study

      2022, Global Transitions
      Citation Excerpt :

      In addition, previous literature has established the evidence that dietary factors such as omega-3 and omega-6 fatty acids, vitamin B6, and folate, played a favoring role in maintaining cognitive function [11,12]. In the past decade, more research in some countries has focused on the relations of dietary sodium and potassium with cognitive function among the elderly, and they drew inconsistent conclusions [13–20]. For example, a cross-sectional study showed that higher sodium intake was associated with cognitive impairment among the Irish elderly [15], but another study performed among the American elderly observed the opposite results [16].

    • High salt diet contributes to hypertension by weakening the medullary tricarboxylic acid cycle and antioxidant system in Dahl salt-sensitive rats

      2021, Biochimie
      Citation Excerpt :

      The excess dietary salt intake had severe adverse effects on health, proved from evidence published in research articles, meta-analysis, clinical trials, and animal studies [3]. Excessive salt uptake promotes cognitive impairment [4,5], is an increased risk of stroke [6], and is also a known main risk factor for developmental hypertension, which leads to cardiovascular disease [7–9]. In hypertension integration, multiple organ systems’ actions are involved, but the role of the kidney is very important to elevate blood pressure.

    • A systematic review of existing peripheral biomarkers of cognitive aging: Is there enough evidence for biomarker proxies in behavioral modification interventions?: An initiative in association with the nutrition, exercise and lifestyle team of the Canadian Consortium on Neurodegeneration in Aging

      2019, Ageing Research Reviews
      Citation Excerpt :

      For example, research shows that nutrient intake and physical activity have an interactive effect on cognitive functions and cognitive trajectory over time. In a prospective longitudinal study of older men and women, high sodium intake in combination with a sedentary lifestyle associated with faster decline in global cognitive functions over 4 years (Fiocco et al., 2012). However, little is known about the interactive effect of physical activity and diet on circulating peripheral biomarkers associated with cognition.

    View all citing articles on Scopus
    View full text