Doctors peer into mental illness

Fusing genetics, biology and the newest imaging technologies, researchers are slowly transforming mental illness — long a loose cluster of symptoms treated by drugs no one quite understands — into clearly defined biological diseases.

‘‘A lot of the psychiatric diagnoses we use are about 100 years old and they go back to a time when we didn’t have genetics, we didn’t have imaging, we didn’t have anything except clinical observations,’’ said Dr. Ed Bullmore, a psychiatry professor at Cambridge University in England.

But someday — maybe within a decade or two — a person who is feeling down will be able to go to the doctor, get a brain scan and a blood test, and be diagnosed with a precise type of depression. They will be given a medication likely to work on the first try, instead of experimenting with poorly understood drug cocktails like today’s patients.

Progress has been slow, stymied by expense, trouble recruiting patients, and the difficulty of sorting through large quantities of data.

‘‘I wouldn’t say it’s mainstream yet, but I would say if you look around the field, quite a few of the leaders are oriented in the same way,’’ said Bullmore, who is using imaging to look at biological markers of schizophrenia.

Two Massachusetts General Hospital scientists, Dr. Hans Breiter and Gregory Gasic, are compiling an encyclopedic database of common mental illnesses by scanning the brains of 1,000 normal, depressed, or cocaine-dependent people, and collecting genetic data and psychiatric evaluations from each.

Then, funded with $8 million from the Office of National Drug Control Policy, they will sift through the information, searching for brain abnormalities and genetic markers that correlate with disease.

Last week, they published their first results in the journal Neuron, identifying a biological abnormality that might predispose people to cocaine addiction. x The amygdala, an almond-shaped nub of tissue in the middle of the brain associated with sensations of fear and pleasure, and where long-term effects of decisions are considered, is smaller in the right side of the brain of cocaine addicts — regardless of how long they have been using the drugs, the researchers found.

They are trying to figure out whether it shrinks from drug use, or whether a small amygdala is what predisposes people to addiction. ‘‘We think what we see here in cocaine addicts is that they have a hard time seeing the negative consequences of their behavior,’’ Breiter said.

The study is limited by its small sample size and can’t definitely distinguish whether the amygdala abnormality is something genetic or developmental, said Marc Kaufman, a cocaine researcher from McLean Hospital who was not involved in the study. But it does give clues for further study, and eventual intervention. ‘‘If you were able to scan someone’s brain, and see that their amygdala is smaller than normal or that there’s an asymmetry, you might want to watch them for drug use patterns,’’ Kaufman said.

The researchers have their sights set even higher: They hope that the blueprint they develop for taking data and culling it for useful connections will be adopted at research centers across the country.

Bullmore praised the project’s ambitions and potential but cautioned that only time will tell if there are meaningful results.

Breiter and Gasic and their 40 colleagues won’t complete their study for another two years. Even if they discover reliable genetic markers for common diseases, it will be a giant step from defining the markers to developing the specialized drugs for the treatment and implementing diagnostic scans.

But Breiter said he is confident that once psychiatric diseases become obvious on a brain scan, they will lose the stigma that now adds to a patient’s burden.

‘‘It’s just a matter of time,’’ he said. ‘‘We can destigmatize mental illness by turning it into any other illness.’’

Dr. Gregor Hasler, who studies biological markers of depression at the National Institutes of Mental Health, said he’s afraid that such progress is still a few decades off.

Because of the time involved, the cost of scanning and taking data on a single patient costs about $10,000, Breiter said. Compare that to a virtually free blood pressure test for heart disease, Hasler said, and it suggests the lengthy time frame it will take for scientists to simply understand the problems — no less to fix them.

Gasic and Breiter said they think the system will be cost-effective as soon as doctors pin down diagnoses. A pricey imaging session will be a bargain when compared with the current state of affairs, when patients miss months of work, tear apart relationships, and live unhappily while doctors adjust drugs, therapy, and diagnoses over months or years. The World Health Organization estimates that mental illness costs Americans about $147 billion a year.

Scans and genes may be the key to a faster, more accurate, and even cheaper diagnosis, Breiter said.

‘‘The brain doesn’t lie, human behavior does,’’ he said.

Carolyn Johnson can be reached at cjohnson@globe.com.