Globally, 10% of the population is affected by Chronic Kidney Disease (CKD). In people ages 65-74, an estimated 1 in 5 men and 1 in 4 women have CKD. Prevalence is rising along with increases in hypertension, diabetes, and obesity. Recently, scientists drew connections between declining kidney function and dementia, highlighting the need for early cognitive testing to improve medical outcomes.
Exploring the connection between end-stage renal disease and dementia
A 10-year cohort study published in Age and Aging revealed:
- Cognitive impairment is common among patients with end-stage renal disease undergoing dialysis.
- There is a graded association between CKD severity and cognitive impairment.
- The mean age of renal patients with dementia was 65.8.
- The eGFR < 60 threshold that denotes risk of CKD can also be used to predict risk of dementia.
- The risk increase was not attributable to stroke or other cardiometabolic conditions.
“The kidneys and the brain, both being end organs, are thought to be susceptible to vascular damage due to similar anatomic and hemodynamic features,” researchers posited, though the exact underlying mechanisms remain unclear.
They added, “While cardiovascular disease and reduction in life expectancy are recognized adverse outcomes of CKD, it is possible that dementia is also part of the risk associated with CKD.”
Treating cognitive deficits can improve patient quality of life and outcomes
Incorporating cognitive testing as part of chronic kidney disease care may have several implications:
- Medication to prevent worsening cognition. Abnormalities in brain capillaries are found in patients with dementia as well as patients with albuminuria, a condition where there is excess albumin blood protein in the urine. Researchers theorize that diabetes or high blood pressure triggers kidney damage, which causes excess protein in the urine and vascular changes in the brain. Patients with albuminuria were found to be at a 50% increased risk of dementia in one study. Early results suggest that treating CKD patients with ACE inhibitors and angiotensin-receptor blockers may have a protective effect on the kidneys and the mind.
- Lifestyle recommendations may be advised to reduce cognitive aging: Some research is looking into the potential for exercise to reduce cognitive decline and depression in patients who have renal impairment. A pilot study found folic acid and thiamine supplements could potentially improve cognitive performance in hemodialysis patients.
- A more paternal stance toward care may be taken. Increasingly, the onus is put on patients to self-manage their treatment. However, multi-domain cognitive impairment is a key factor contributing to why patients decide to withdraw from dialysis, undermining the shift from paternalistic to patient-driven models of care. Adherence to treatment protocols is especially important in patients who receive transplants.
- Diagnosis may aid prognosis. A patient’s prognosis may change when CKD and dementia are both present, as at least one study suggests higher mortality rates in this cohort.
- Support services can be arranged for at-risk patients. Researchers found 70% of patients with CKD and cognitive declines self-reported functional dependence in daily living, indicating a need for assistance with everyday tasks or the inability to drive safely.
- Kidney impairment will be detected and treated earlier. The general odds of a patient with CKD having reduced cognitive ability increases by 23% — with worsening mental function among patients with more advanced stage kidney disease. However, even those with milder forms of kidney impairment were at increased risk of cognitive impairment, suggesting the need for earlier intervention.
MoCA screening tools validated to test CKD patients for cognitive decline
Multiple peer-reviewed studies have validated the effectiveness of MoCA in detecting cognitive declines and dementia in patients with diminished renal function, including:
- “A significant association between the visuospatial executive function domain score of the Montreal Cognitive Assessment and the maximum arteriolar dilation as response of retinal arterioles to the flicker light stimulation was obtained.” The MoCA cut-off was set at 24 for patients on hemodialysis, as validated by two studies. Further, researchers noted an approximately three-fold higher prevalence of adverse outcomes (including increased mortality).1
- “Older adults with preclinical cognitive impairment and CKD had different cognitive and vascular function than those without CKD, and an indicator of vascular function may have a relationship with cognitive function in older adults.” Scientists explored the possibility of vascular dysfunction as a mechanism for cognitive decline in older patients with CKD.2
- “Hemodialysis patients with cognitive impairment treated with thiamin and folic acid had a significant improvement in MoCA score.” Studying patients who scored 26 or lower on MoCA, researchers found the proportion of adverse events among the group treated with thiamin and folic acid supplements was “substantially lower.”3
- “The Montreal Cognitive Assessment, a widely available and brief cognitive screening tool, showed high sensitivity and moderate specificity in detecting severe cognitive impairment in patients on maintenance hemodialysis.” Researchers assessed cognitive function in a cohort of 150 patients on hemodialysis. Of the 150 participants, 21% had normal cognitive function, 17% had mild cognitive impairment, 33% had moderate impairment, and 29% had severe impairment. The study found a sensitivity of 86% and specificity of 55% for severe impairment. The MMSE and Mini-Cog had lower predictive performances.4
Early cognitive impairment detection and treatment is a crucial first step, as keeping patients cognitively intact ensures that they are able to follow their physician’s instructions and live healthier, happier lives.
MoCA offers highly sensitive, highly specific tools for assessing cognitive decline and dementia in renal patients. Visit us online for more information and adapted testing content.
References:
1 . Angermann, Susanne et al. “Cognitive impairment and microvascular function in end-stage renal disease.” International journal of methods in psychiatric research vol. 31,2 (2022): e1909. doi:10.1002/mpr.1909. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9159686/.
2 . Hannan M, Collins EG, Phillips SA, Quinn L, Steffen A, Bronas UG. Cognitive and vascular function in older adults with and without CKD. Aging Clin Exp Res. 2021 Jul;33(7):1885-1894. doi: 10.1007/s40520-020-01695-w. Epub 2020 Sep 9. PMID: 32902822; PMCID: PMC8171583. Retrieved from: https://pubmed.ncbi.nlm.nih.gov/32902822/
3 . Lu R, Fang Y, Zhou Y, Che M, Shen J, Liu Q, Zhang H, Pan S, Lin Y, Wang Q, Mou S, Ni Z, Gu L. A pilot study of thiamin and folic acid in hemodialysis patients with cognitive impairment. Ren Fail. 2021 Dec;43(1):766-773. doi: 10.1080/0886022X.2021.1914656. PMID: 33913373; PMCID: PMC8901284. Retrieved from: https://pubmed.ncbi.nlm.nih.gov/33913373/
4 . Evaluation of Screening Tests for Cognitive Impairment in Patients Receiving Maintenance Hemodialysis. David A. Drew, Hocine Tighiouart, Jasmine Rollins, Sarah Duncan, Seda Babroudi, Tammy Scott, Daniel E. Weiner and Mark J. Sarnak. JASN April 2020, 31 (4) 855-864; DOI. Retrieved from: https://jasn.asnjournals.org/content/31/4/855
Additional Resources:
https://www.ajmc.com/view/poor-kidney-function-significantly-linked-with-dementia-incidence
https://www.kidney.org/kidneydisease/global-facts-about-kidney-disease
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