ANTIDEPRESSANTS not only treat depression, but can also help prevent heart
disease. The scientists who have made this discovery think that improved mood
makes the difference, rather than direct action by the drugs.
People who suffer from severe depression are up to four times as likely to
die from heart disease triggered by obstructed blood flow as people who are not
depressed—even allowing for classical risk factors such as smoking and
high cholesterol levels. In fact, depression is a greater risk factor than
smoking.
In 1996, Dominique Musselman of Emory University in Atlanta, Georgia, and her
colleagues tried to find out if depressed people are at risk because they have
higher levels of sticky platelets in their blood. Following injuries, platelets
stick together and clot to stop us bleeding to death. Too much clotting would
cause heart problems.
The researchers took blood samples from both depressed and healthy people and
examined their platelets for evidence of stickiness. They measured
characteristic chemical changes that occur on the surfaces of platelets as they
prepare to clot and become sticky. The numbers of sticky platelets in depressed
people, they found, were 41 per cent higher than in healthy volunteers.
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Now the team has shown that anti-depressant drugs can cut down the
numbers of sticky platelets in the blood of depressed patients. They monitored
15 patients taking a drug from a class of antidepressants known as selective
serotonin reuptake inhibitors, which includes Prozac. The number of sticky
platelets fell in all the patients, and even dropped back to normal levels in
some of them, Musselman told a meeting of the Society of Biological Psychiatry
in Washington DC last week.
“Treatment diminishes the stickiness of the platelets,” she concludes. But
one big question still remained. Does the drug lower the platelet stickiness
directly, or does a happier mental state do the trick?
To find out, Musselman is running a placebo trial. Early results suggest
people who don’t report any improvement in mood after taking antidepressants
also don’t have much reduction in platelet stickiness. In contrast, people whose
mood improves even with a placebo do show less platelet stickiness. This result
suggests that mood improvement is the key.
