By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Diabetes and pre-diabetic conditions appear to worsen the risk of Alzheimer's disease but drugs that help regulate blood sugar may help patients with dementia as well, researchers report.
Several studies presented at a meeting in Madrid, Spain, this week show that patients who take some of the drugs commonly prescribed to type-2 diabetes were less likely to have Alzheimer's disease.
The findings worried Alzheimer's experts, who say the global explosion of diabetes may also worsen the burden of Alzheimer's disease, already the leading cause of dementia.
Many more people will be at risk of Alzheimer's as the large "baby boom" generation ages, said William Thies, vice president of medical and scientific relations for the U.S.-based Alzheimer's Association.
"It is only going to get worse," he said in an interview. "We are going to have profound aging. ... We are likely to bankrupt the health-care systems in most of the Western world."
There is no cure for Alzheimer's disease or other forms of dementia, which affect an estimated 28 million people globally. More than 4 million people have Alzheimer's in the United States alone.
Causes of Alzheimer's are poorly understood, but it can be linked with diet and exercise, and researchers told the International Conference on Alzheimer's Disease and Related Disorders they found clear links with diabetes.
Two teams looked at patients who take diabetes medications known as glitazones or thiazolidinediones (TZDs), including pioglitazone, sold under the brand name Actos by Eli Lilly and Co. and Takeda Pharmaceutical Co., and rosiglitazone, sold as Avandia, Avandamet and Avandaryl by GlaxoSmithKline Plc.
Donald Miller of the Boston University School of Public Health looked at 142,328 Department of Veterans Affairs patients and found that those prescribed TZDs had lower rates of Alzheimer's. They estimated that the veterans taking TZDs had almost 20 percent fewer new cases of Alzheimer's than those who took insulin.
Dr. David Geldmacher of the University of Virginia and colleagues tested pioglitazone in Alzheimer's patients who did not have diabetes. Alzheimer's appeared to progress more slowly in the 12 out of 25 patients who took pioglitazone.
Several studies also found that people with poor blood sugar control have a higher risk of Alzheimer's.
Dr. Weili Xu and colleagues from the Karolinska Institutet in Sweden followed 1,173 people aged 75 and older for nine years. More than 300 developed Alzheimer's.
Those with borderline diabetes had an almost 70 percent increased risk of developing dementia and Alzheimer's disease, Xu's team told the conference.
Rachel Whitmer of Kaiser Permanente in Oakland, California, studied 22,852 patients with type 2 diabetes for eight years and found those with very poor blood sugar control were much more likely to develop dementia. Those with the worst blood glucose levels, as measured by a test called a1c used to determine long-term blood sugar levels, were 78 percent more likely to get dementia.
Nearly a third of U.S. adults have either type-2 diabetes or higher than normal blood sugar levels, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
"Physical activity is probably the single best way to regulate your blood sugar levels," Thies said.
He said the studies show that the TZD or glitazone drugs might be promising not only to treat, but to prevent Alzheimer's.