This Hormone Might Stave Off Alzheimer's

Cate Stevenson, BA

Alzheimer's is a difficult disease to track. Its progression is often marked by psychological and physiological symptoms that can be bewildering and frustrating to diagnose. Alzheimer's is also a condition that has a reputation for being notoriously difficult to treat: in fact, there is no standard treatment that can halt the disease.

Given the difficulty the disease poses on all fronts, prevention seems to be the most important and hopeful way of keeping Alzheimer's at bay. But how do you go about protecting against this brain disease? According to a recent study, high blood levels of a certain hormone can go a long way to fending off Alzheimer's before it ever takes hold in the brain.

Leptin is a hormone that regulates your appetite. Researchers began to study the hormone after some data showed that leptin not only produces a feeling of fullness, but also has a beneficial effect on the hippocampus. Your hippocampus is a part of the brain that plays a role in memory function.

Studies have previously shown that people with Alzheimer's disease have lower levels of leptin. The problem was that scientists couldn't determine which came first, the lower leptin levels or the decline in mental function. The researchers turned to the Framingham Heart Study for answers. The massive heart study has followed residents of a Massachusetts community for decades. Leptin levels had been measured in 785 Framingham participants in the early 1990s, so, for the new study, the research team had 198 of them undergo MRI scans that measured brain volume. They did this an average of 7.7 years after the leptin was measured. The researchers also kept note of new Alzheimer's diagnoses among the study participants.

The research team found that higher leptin levels were associated with a lower incidence of Alzheimer's and all other forms of dementia. They found that 25% of participants with the lowest leptin levels had a 25% risk of developing Alzheimer's over a 12-year period. This was compared to only six percent for those with the highest leptin levels. Lower leptin levels were also associated with a greater decrease in total brain size.

The researchers can't say exactly what it is that leptin does to help the aging brain. They are not suggesting that you go out and get leptin or increase your leptin levels. They hope that a marker such as low leptin might be useful as an indicator that the risk for Alzheimer's is there, in which case preventative therapy could be started right away. Usually, Alzheimer's treatment is started when the disease has already progressed.

Sources:
This Hormone Might Stave Off Alzheimer's, Lieb W et al., "Association of Plasma Leptin Levels With Incident Alzheimer Disease and MRI Measures of Brain Aging," JAMA, 2009; 302(23): 2,565-2,572.

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