Brain scan predicts heart attack risk
Stress is often cited as a cause of heart attacks and strokes. Now scientists in the US have shown for the first time that people with higher than average activity in the brain's fear centre, or amygdala, are significantly more likely to develop heart disease.
Writing in the Lancet, Massachusetts General Hospital psychiatrist Roger Pitman and his colleagues looked at data from 239 individuals who were being investigated for other conditions.
These subjects, who included both males and females and were aged 55 years on average, had undergone whole body PET - positron emission tomography - scans. This imaging method provides a read-out of metabolic activity in different tissues, so the researchers could pull out results for the bone marrow, artery walls and the brain region called the amygdala in each of the patients.
Individuals with high levels of activity in the amygdala, indicating above-above levels of stress and arousal, were more than 1.6 times more likely to suffer a subsequent cardiovascular event, such as a stroke or heart attack, the team found. And the higher the level of activity in the amygdala, the sooner a patient suffered an event.
These same patients also had high levels of signals arising in their bone marrow and spleen, suggesting that the inflammatory arm of the immune system was being activated. This inflammation appeared to gravitate to the walls of arteries, which also showed up as hot spots on the PET scans.
Putting their findings together, the researchers speculate that chronic stress, signalled through the brain's amygdala, stimulates the release from the bone marrow of immune cells, which migrate to the walls of blood vessels where they trigger inflammatory responses linked to the formation of atheroma, the fatty substance that clogs diseased arteries. Such as mechanism has been suggested previously, but never objectively observed.
Stress, the team emphasise, and specifically the responses of the brain's amygdala, can therefore be regarded an independent risk factor for heart disease. So stress management might be a fruitful avenue worth pursuing alongside traditional therapies like control of cholesterol levels and blood pressure.