QUICK STUDY : A weekly digest of new research on major health topics

Tuesday, February 21, 2006

sleep

Melatonin supplements seem to have little effect on slumber.

· THE QUESTION Traveling between time zones or working odd hours can wreak havoc on sleep. So, too, can certain medications or health problems. Might this be ameliorated by supplements of the hormone melatonin -- thought to be involved in regulating the body's daily rhythm?

· THIS STUDY reviewed 15 studies in which 524 people with sleep disorders had been randomly assigned to take melatonin or a placebo for three months or less. The hormone had no measurable effect on the participants' ability to fall asleep, whether they were deprived of sleep because of jet lag or shift work or because of medical or medication problems. The latter group registered a 2 percent improvement in "sleep efficiency" -- the amount of time in bed spent asleep -- but the authors described this as too small a change to be important. Sleep efficiency did not improve for shift workers and people with jet lag. A separate review of 17 studies, with 651 participants, found that people who took the hormone showed no adverse effects.

· WHO MAY BE AFFECTED BY THESE FINDINGS? The estimated 40 million Americans who have trouble sleeping.

· CAVEATS The study did not determine whether melatonin affects daytime fatigue or is safe for long-term use.

· FIND THIS STUDY Feb. 10 online edition of BMJ; abstract available at http://www.bmj.com (click "Online first").

· LEARN MORE ABOUT sleep disorders at http://sleepfoundation.org and http://www.ninds.nih.gov .

cholesterol

Eating a red or white grapefruit daily may lower lipid levels.

· THE QUESTION Fruits and vegetables top most lists of foods that may help keep cholesterol levels in line, with people advised to eat five servings a day of apples, broccoli, carrots and the like. What effect might grapefruit have?

· THIS STUDY involved 57 adults with heart disease and high cholesterol, despite having taken a cholesterol-lowering statin. They were randomly assigned to add one red grapefruit, one white grapefruit or no grapefruit each day to their normal diet. Based on blood tests, people who ate grapefruit for 30 days had lower total and low-density lipoprotein ("bad") cholesterol levels than before they added the citrus fruit to their diets. Those who ate red grapefruit also lowered their triglyceride levels. Lipid levels did not change for the group that did not eat grapefruit.

· WHO MAY BE AFFECTED BY THESE FINDINGS? People with heart disease and high cholesterol. An estimated 107 million Americans have elevated cholesterol.

· CAVEATS All participants had bypass surgery a year or more before starting the study; whether the same benefits would apply to others remains uncertain. Grapefruit has been shown to interact negatively with various prescription medications; including some statins. People considering adding grapefruit to their diet may want to consult a doctor.

· FIND THIS STUDY Feb. 3 online edition of the Journal of Agricultural and Food Chemistry; abstract available at http://pubs.acs.org/journals/jafcau (click "articles ASAP").

· LEARN MORE ABOUT cholesterol at http://www.americanheart.org . For more on grapefruit and drug interactions, go to http://www.druginteractioncenter.org .

cognitive decline

Some drugs may precipitate loss of mental skills in older people.

· THE QUESTION A variety of drugs -- antihistamines, antidepressants, analgesics, anti-inflammatories and more -- are classified as anticholinergics because they block the transmission of particular nerve impulses. When taken by older people, might these drugs affect cognitive abilities?

· THIS STUDY analyzed medical and neurological data on 327 people older than 60 who had no evidence of dementia; 30 people (9 percent) took at least one anticholinergic drug for at least a year, and the others took none. After a year, 80 percent of those who took the drugs consistently, compared with 35 percent of the group that took no anticholinergics, had been diagnosed with mild cognitive impairment (based on tests of such things as reaction time, attention, recall and verbal fluency). But after eight years, diagnoses of overall dementia were nearly the same: 16 percent among those who took the drugs, 14 percent for those who did not.

· WHO MAY BE AFFECTED BY THESE FINDINGS? Older people taking anticholinergics. Many nursing home residents take at least two such drugs.

· CAVEATS The study did not specify the effects of each of the 27 anticholinergic compounds taken by participants.

· FIND THIS STUDY Feb. 1 online edition of BMJ; abstract available at http://www.bmj.com (click "Online first").

· LEARN MORE ABOUT cognitive change and aging at http://www.mayoclinic.com (search for "expand your mind") and http://www.cdc.gov/aging (click "Health Information for Older Adults," then "Mental Health").

--Linda Searing

The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.