To: Henry Niman who wrote (17921 ) 4/2/1998 9:33:00 AM From: Henry Niman Respond to of 32384
Speaking of Alzheimer's and SERMs, sounds like throwing in some rexinoid (Targretin) may also help: Insulin resistance linked to some Alzheimer's By Theresa Waldron Patients with Alzheimer's disease appear to have abnormal insulin levels, both in plasma and cerebrospinal fluid (CSF), which may be one explanation for the pathophysiology of the disease, say Seattle investigators. Suzanne Craft, Ph.D., associate professor of psychiatry at the University of Washington and the Veterans Affairs Puget Sound Health Care System, and colleagues examined paired fasted plasma and CSF insulin levels in 25 patients with Alzheimer's disease and 14 healthy adults. The Alzheimer's patients had lower CSF insulin levels, higher plasma insulin levels, and a reduced CSF-to-plasma insulin ratio when compared with patients without the disease, the investigators reported in a recent issue of Neurology (1998; 50:164-168). Differences in insulin level were more pronounced in patients with more advanced Alzheimer's disease. The findings indicate that there may be a problem with the ability of insulin to promote glucose utilization, both in the periphery and the brain, for some patients with disease, Dr. Craft explained. The brain is "completely dependent on obtaining glucose from the peripheral glucoregulatory system," she said. "The brain can't store glucose the way the periphery can, and it can't synthesize glucose," Dr. Craft said. "So peripheral glucose metabolism efficiency is important in getting an optimal supply of glucose to the brain. Insulin in the brain isn't working effectively to promote glucose utilization. It's a defect in insulin action." The researchers were surprised to find that the patients showing insulin resistance did not have the apolipoprotein E4 (Apo E4) gene often associated with Alzheimer's disease, Dr. Craft said. Conversely, patients with Apo E4 did not show insulin resistance. Because peripheral insulin resistance may be a risk factor for Alzheimer's disease, there may be some benefit to treating insulin resistance with oral antidiabetic agents, the Washington psychiatrist said. It remains to be seen whether the presence of insulin resistance can be used to aid diagnosis in a patient with suspected Alzheimer's disease, according to Dr. Craft. "We're not at the point where it can be used as a diagnostic test," she said. This study is a "very intriguing piece of basic science," commented Warren Strittmatter, M.D., professor of medicine at Duke University Medical Center in Durham, N.C. Further studies on insulin and other proteins, such as immunoglobulins, may be helpful in looking for the mechanism by which Apo E-4 contributes to Alzheimer's disease risk, said Dr. Strittmatter, who is one of the investigators who uncovered the link between Apo E-4 and Alzheimer's disease. "I'd look at other proteins like insulin that are transported across [the blood-brain barrier] to see whether or not the observation they report here is unique to insulin or whether it's a more general mechanism of protein transport," Dr. Strittmatter said. Cell uptake across the blood-brain barrier may be abnormal in these patients, he explained.