Uric acid (UA) is a major contributor to naturally-occurring
antioxidant activity and is thought to have protective effects against neurodegenerative processes. However, UA is also implicated as a risk factor in vascular, including
cerebrovascular, disease. Its association with, and role in,
dementia and its component diseases including
Alzheimer's disease (AD) and
vascular dementia (VaD) remains unclear and inconsistently studied. Changes in blood
lipids, particularly
cholesterol measures, have also been implicated in
dementias although the relationship or interactions with UA have been little studied.We have measured plasma UA and
lipids taken from 187 subjects first attending a general hospital neurology department for symptoms associated with
dementia, and from a series of 79 healthy control subjects. Diagnoses of AD and VaD were made following neuroimaging; laboratory measures were compared between
dementia and control groups and between AD and VaD subgroups. No overall change in UA was seen in
dementia, although a substantial and highly significant reduction was found in the AD patients. Reduced values in total
cholesterol, HDL, and
LDL were found in
dementia, independent of
statin treatment. Further investigation found a significant reduction of HDL only in the VaD group, while total
cholesterol was significantly reduced in both AD and VaD subjects.These findings indicate that in our Chinese sample, UA deficits are specifically associated with AD, while deficits in
HDL cholesterol found in
dementia tend to be greater in VaD.