Association between dietary sodium intake and cognitive function in older adults

Abstract

OBJECTIVES To examine the association of dietary sodium intake with cognitive function in community-dwelling older adults. DESIGN Cross-sectional study SETTING Southern California community PARTICIPANTS White men (n=373) and women (n=552), aged 50–96 years from the Rancho Bernardo Study, a longitudinal study of cardiovascular disease risk factors and healthy aging. MEASUREMENTS During the 1992–1996 research clinic visit, a food frequency questionnaire was used to determine daily sodium intake; cognitive function was assessed with Trails Making Test, part B (Trails B), Mini-Mental State Exam (MMSE), and Verbal Fluency Test (VFT); and medical, clinical and demographic information was obtained. Linear regression was used to assess the association between calorie-adjusted sodium intake and cognitive test scores with adjustment for demographic, behavioral and health measures. Logistic regression examined the odds of having cognitive impairment by sodium intake. RESULTS Lower sodium intake was associated with poorer performance on Trails B (p=0.008) and MMSE (p=0.003) after controlling for age, sex, and education. Associations did not differ by sex, but there was a significant interaction by age for the Trails B: older (≥80 years), but not younger, adults showed worse performance with lower sodium intake (p=0.03). Associations remained significant after additional adjustment for smoking, alcohol intake, exercise, body weight, cardiovascular risk factors, kidney function, diuretic medication use, and diet quality. Lower daily sodium intake was associated with increased odds of cognitive impairment on the MMSE (score < 26; OR per SD decrease = 1.12, 95% CI 1.08, 1.16). CONCLUSION Lower sodium intake was associated with worse cognitive function in older community-dwelling adults. For the maintenance of cognitive health, older adults may be advised to avoid very low sodium diets.

High sodium intake increases blood pressure and risk of kidney disease. From the Science of Salt: A regularly updated systematic review of salt and health outcomes (August 2016 to March 2017)

“…The outcomes examined were diverse: Six studies assessed mortality outcomes, four studies assessed morbidity outcomes, three studies assessed outcomes related to symptoms/quality of life/functional status, studies assessed BP outcomes; eight studies assessed other clinically relevant surrogate outcomes; and nine studies assessed physiologic outcomes (Table ) . A range of outcomes were captured by the studies considered lower quality, including all‐cause mortality, gastric cancer, end‐stage renal disease requiring dialysis or transplant, cardiovascular events, hypertension prevalence, headaches/migraines, quality of life, multiple sclerosis, BP, cognitive function, osteoporosis risk and prevalence, nonalcoholic fatty liver disease, type 2 diabetes, carotid atherosclerosis, bone mineral density, changes in left ventricular mass, inflammatory markers, albuminuria, and other urinary markers . Most of these studies (n = 40) found adverse effects of dietary salt on health outcomes and benefits of a sodium‐restricted diet on health, except for 7 that were neutral and one reported worsening symptoms with a sodium‐restricted diet in the elderly …”

Dietary Patterns and Cognitive Function among Older Community-Dwelling Adults

“…In addition, nuts and legumes are included as one component of the AHEI-2010 score, while these foods are considered separately in the aMed diet, lending them more weight. Furthermore, the sodium component, which is unique to the AHEI-2010 score, may partially mask associations as low sodium intake has previously been linked to lower cognitive function in the RBS cohort [ 47 ]. There is sparse literature examining the association between the AHEI-2010 diet and cognitive function [ 10 , 16 ] and no other study has had a follow-up of this length.…”

Link Between Dietary Sodium Intake, Cognitive Function, and Dementia Risk in Middle-Aged and Older Adults: A Systematic Review

“…This review includes data from one clinical trial [27], six longitudinal cohort studies [28][29][30][31][32][33] (of which three studies only reported results of cross-sectional analyses [30,31,33]) and eight crosssectional studies [34][35][36][37][38][39][40][41] (Table 1). Six of the studies were conducted in the United States of America (USA) [27-29, 31, 32, 39], two studies were conducted in Australia [33,36], and one study each was conducted in Canada [30], Turkey [34], Korea [37], Poland [35], Scotland [38], Ireland [40], and China [41].…”

“…Mean age was 65.4 years (SD = 6.8) with a follow-up time of six months. The six [28][29][30][31][32][33] cohort studies had sample sizes ranging from 1,194 [29] to 6,426 [28] participants. Age ranged from 40 to 96 (only one study [32] included participants aged 40 years and above, with the mean age of participants higher than 45 years old).…”