According to Dr. Miller, it has been known for some time that mental stress can cause vasoconstriction [narrowing of blood vessels]. He added that his group was the first to show that laughter has a beneficial effect on the endothelium. They wondered whether positive emotions evoked by music would have a similar effect.
To determine the effect of music on endothelial function, the researchers conducted a study that comprised 10 participants: healthy, nonsmokers — 7 male and 3 female — with a mean age of 36 years. They selected 30 minutes of music they enjoyed. To minimise emotional desensitisation, participants were told to avoid listening to this particular music for 2 weeks prior to the start of the study.
"We didn’t assign music for them to listen to. We wanted participants to emote positively based on their previous experience with certain music," said Dr. Miller.
Volunteers were also asked to identify music that made them feel anxious.
On four separate occasions, 1 week apart, the subjects' endothelial function was assessed by measuring blood flow in the upper arm. On each occasion, brachial artery flow–mediated dilation [a parameter used to assess endothelial dysfunction – used to determine cardiovascular risk] was measured at baseline and after 30 minutes of: (a) enjoyable music, (b) anxiety-provoking music, (c) a humorous video clip and (d) a relaxation tape.
The researchers found that, compared with baseline, the subjects' mean flow-mediated dilation: