Alzheimer’s disease and vascular dementia both are, respectively, the first and second most common neurodegenerative diseases. Although dementia is a massive global issue, the actual mechanisms causing these diseases are relatively unknown with multiple diseases increasing the risk of developing a dementia.
A recent study has established a link between albuminuria and both Alzheimer’s disease and vascular dementia. By following a dementia-free Japanese-community of 1562 people, aged 60 years and above, the researchers established that albuminuria significantly increased the risk of both Alzheimer’s disease and vascular dementia.
Albuminuria And Dementia
Albuminuria is a disease where the kidneys fail to effectively filter components of the blood and allow for proteins (like albumin) to leak through into the urine. This is an early sign of chronic kidney disease, which has a higher risk of onset with age and associated with diabetes and high blood pressure; both of which are also conditions which increase the risk of Alzheimer’s disease and vascular dementia.
Previous research has investigated the relationship between albuminuria and poor renal (kidney) filtration with cognitive decline and dementia, but these have all focussed on simple cognitive scoring systems and ignored the development of specific dementia sub-types. This study has built upon the previous research by utilising neuroimaging and post-mortem brain autopsies to classify the specific dementias which develop in people with albuminuria.
In addition, the authors state that this is the first study to assess the risk of Alzheimer’s and vascular dementia from the combination of having a low filtration rate and albuminuria.
While albuminuria was significantly associated with both vascular dementia and Alzheimer’s disease, a low renal filtration rate was only associated with a heightened risk of vascular dementia. These findings warrant further investigation to uncover the specific effects of albuminuria and low renal filtration rates on the development of specific dementia sub-types.
Further investigation within a laboratory setting may be able to elucidate the specific mechanisms that lead to an increased risk of Alzheimer’s disease and vascular dementia from albuminuria; potentially through elucidating the relationship between vascular factors and renal function on the brain.
Losartan: RADAR Trial
The association of albuminuria with high blood pressure and the renin-angiotensin system mean that the condition is often treated with anti-hypertensive drugs which act through the renin-angiotensin system. This links the findings from this study to the efforts of the ‘Reducing pathology in Alzheimer’s Disease through Angiotensin taRgeting’, AKA RADAR trial; which aims to treat Alzheimer’s disease using losartan, an anti-hypertensive drug that targets the renin-angiotensin system.
In fact, losartan has been used previously to treat albuminuria, and may be an effective therapeutic strategy to improve prognosis in albuminuria, vascular dementia, and Alzheimer’s disease. The increase in blood pressure and dysregulation of the renin-angiotensin system may be one of the contributing factors that leads to Alzheimer’s disease and associated dementias.
Keita Takae, Jun Hata, Tomoyuki Ohara, Daigo Yoshida, Mao Shibata, Naoko Mukai, Yoichiro Hirakawa, Hiro Kishimoto, Kazuhiko Tsuruya, Takanari Kitazono, Yutaka Kiyohara, Toshiharu Ninomiya
Albuminuria Increases the Risks for Both Alzheimer Disease and Vascular Dementia in Community‐Dwelling Japanese Elderly: The Hisayama Study
Journal of the American Heart Association. January 20, 2018 https://doi.org/10.1161/JAHA.117.006693
Author: Geoffrey Potjewyd; Regenerative Medicine & Neuroscience PhD student at the University of Manchester. Image: ‘Kidney proximal tubule’ by David Gregory & Debbie Marshall, Welcome Images. CC BY