You can tell a lot about a person by looking at a scan of their amygdala, the almond-shaped structure near the center of the brain, the place where fear, emotional behavior, and motivation are integrated.

Of course, few of us are likely to get the chance to scan someone else's brain, but a recent study suggests scans could be a new route to better prevention and diagnosis of mental health disorders like depression and anxiety.

These disorders affect tens of millions of people a year in the U.S. alone, so there is a lot of interest in predicting who may develop mental health disorders down the road — the thought being that if doctors can tell who is at greater risk earlier, they could provide help before the disorders spiral out of control.

Of course, scanning the brains of the entire population is difficult and costly, so simpler methods of prediction are the real goal.

And that’s just what the small new study has done. Researchers scanned the brains of a group of college students with MRI (magnetic resonance imaging, a non-invasive procedure) technology. The region of interest was the amygdala, since it governs fear and anxiety.

As expected, there were some students whose amygdalae were more reactive when they saw pictures of angry or fearful faces, and the researchers identified those students. They then tracked all the participants for up to four years following the initial scans, asking the students to answer online questionnaires every few months about any major life events (divorces, deaths of loved ones, unemployment) and any symptoms of depression and anxiety they might be experiencing.

The more reactive the participants’ amygdalae were in the initial MRI scan, the greater the number of symptoms of depression and anxiety they reported feeling throughout the four-year study period, the researchers discovered.

The value of this connection is not only to predict a person's likelihood of becoming depressed or anxious, but to intervene before symptoms become severe enough to disrupt a person’s life — their productivity at work or relationship with their families. It is possible some types of intervention, like talk therapy or regular exercise, could be recommended before a person has any symptoms at all.

“It's clear that treating mental illness is generally ineffective and, as with other branches of medicine, that the best strategy is to prevent illness in the first place,” said study author Ahmad Hariri in a news release.

“Our findings contribute to ongoing efforts to develop strategies for preventing mental illness by identifying a measure of brain function that distinguishes those at greatest risk before they become ill.”

Scanning the brains of the entire population is difficult, costly and not practical, so simpler methods of prediction are the real goal. The team is also doing genetic studies to see how our genes may also predict who’s more or less susceptible to depression and anxiety in the future. If a blood test could take the place of the MRI scan, it would be much simpler, cheaper, and more convenient for the patient.

There are treatments for depression and anxiety that are effective right now: It may just take some time to find the right one for you. If you’re suffering from depression or anxiety, don’t suffer in silence — get help by reaching out to a friend or family member first, and then finding a mental health professional you trust.

The study was carried out at Duke University and is published in the journal, Neuron.