Gout is caused by hyperuricemia - an overproduction or underexcretion of uric acid in the blood. It is this build up of uric acid that researchers believe may protect against Alzheimer's.
Gout is a common form of inflammatory arthritis. It is caused by hyperuricemia - an overproduction or underexcretion of uric acid in the blood. This can lead to the deposition of uric acid crystals, or monosodium urate, in body tissue, which causes inflammation.
Gout often occurs in the big toe first, and can go on to attack the ankles, heels, knees, elbows, wrists and fingers. When the condition first arises, symptoms normally disappear within a few days. But as time goes on, attacks can occur more frequently and last longer.
According to the study authors - including Hyon K. Choi of the Division of Rheumatology, Allergy and Immunology at Massachusetts General Hospital - excess uric acid in the blood has been linked to increased risk of cardiovascular and kidney diseases. However, it may also have a neuroprotective effect, with some studies indicating uric acid may prevent or slow Parkinson's disease.
This got the team thinking; could uric acid protect against Alzheimer's disease? With their study, the results of which are published in the Annals of Rheumatic Diseases, they sought to find out.
Gout linked to 24% reduced risk of Alzheimer's
The researchers used data from The Health Improvement Network (THIN) - a computerized medical record database involving 10.2 million patients from 580 general practices in the UK - to assess whether gout was linked to reduced risk of Alzheimer's.
They identified 59,224 patients with an average age of 65 with gout, alongside 238,805 patients without the condition. All patients had been registered with a general practice for at least a year before study baseline, and the team excluded patients who had been diagnosed with gout or dementia before this point.
During an average follow-up of 5 years, the team identified 309 new Alzheimer's cases among patients with gout, while 1,942 cases were found among patients without gout.
After accounting for patients' age, sex, body mass index (BMI), lifestyle factors, socioeconomic status, heart conditions and use of heart drugs, the researchers found that patients with gout were at 24% lower risk of developing Alzheimer's than those without gout.
While the team says they cannot cite the exact reasons for this association, they hypothesize that - as shown in previous studies of neurological diseases - uric acid may play a role.
"In animal models of Parkinson's disease, uric acid has shown neuroprotective effects against oxidative stress-induced dopaminergic neuron death," the authors explain, "and similar neuroprotective effects have been observed in animal models of other neurological conditions, such as multiple sclerosis and spinal cord injury."
The researchers add:
"In conclusion, our findings provide the first population-based evidence for the potential protective effect of gout on the risk of Alzheimer's disease and support the purported neuroprotective role of uric acid.
If confirmed by future studies, a therapeutic investigation that has been employed to prevent progression of Parkinson's disease may be warranted for this relatively common and devastating condition."
Medical News Today recently reported on a study published in the journal Brain, in which researchers identified amyloid protein - a hallmark of Alzheimer's - in the brains of adults as young as 20.