Older people with kidney disease have a higher risk of dementia, and the risk increases with the rate and stage of kidney function decline, says new study findings published in the journal Neurology.
The findings have led researchers at the Karolinska Institutet in Sweden to stress the significance of screening and monitoring for dementia in people with kidney disease.
“Our study underscores the importance of low kidney function as a possible under-recognised risk factor for dementia,” says study co-author Professor Juan Jesus Carrero.
“It also shows that the dementia risk likely attributed to kidney disease is similar or larger than that observed for other well-established risk factors for dementia, including cardiovascular disease and diabetes.”
Dementia is already associated with bad general health and increased risk of death, and has a global prevalence estimate of 5-7 per cent in people over 60.
Also very common among older adults is chronic kidney disease, with a global population prevalence of 25-40 per cent depending on age.
In Australia, one in 10 (2.4 million) have some form of chronic kidney disease (CKD). Kidney Health Australia estimates that 50 per cent of this number are over 65 years old and 30 per cent over 75 years old.
“CKD, diabetes and cardiovascular disease each have a strong association with presence of cognitive impairment,” says Kidney Health Australia’s Make the link: Kidneys, diabetes, heart report.
Even a mild reduction in kidney function is also associated with an increased risk of other diseases.
“Prospective studies of older adults have reported that moderate to severe reduction in kidney function is associated with worse cognitive performance and a higher risk of cognitive decline, and that a faster rate of kidney function decline is associated with global cognitive decline and incident dementia,” says the report.
“Low cognitive score has also been linked with an increased risk of death in elderly persons.
“Given the increasing health burden related to dementia in Australia, the implications of comorbid CKD, diabetes and cardiovascular disease for cognitive ageing are of critical importance.”
Currently, identifying potentially modifiable risk factors is one of few viable dementia prevention strategies. Improving and maintaining kidney function could significantly reduce dementia incidence globally.
In the Swedish study of more than 325,000 individuals 65 years of age or older, researchers found a clear link between poor kidney function and a higher probability of dementia diagnosis.
Read more: Keep your kidneys healthy
Nearly 19,000 cases of dementia were detected after five years, with lower kidney function leading to higher incidence rates of dementia.
“This is, to our knowledge, the largest study to date on kidney function and dementia, exceeding by several fold the sample size of all previous studies combined and evaluating the whole spectrum of kidney function,” says Prof. Carrero.
“Even though we cannot determine causality based on these findings, our analysis suggests that as many as 10 percent of dementia cases could potentially be attributed to chronic kidney disease,” says corresponding author Hong Xu.
“We hope that our findings may help health care policy makers to develop and implement appropriate strategies for screening and monitoring for dementia in persons with kidney disease and vice versa, as well as assist in health service planning.”
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