The number of Americans who received psychotherapy increased slightly from 1987 to 1997, according to a large national study, and rose significantly for two groups: older adults and the unemployed.

But the average length of time patients spent in the consulting room dropped precipitously over the same period, the study found, and the percentage of patients who combined psychotherapy with psychiatric medication nearly doubled.

The researchers said that the findings reflected the effect of managed care and the growing popularity of brief forms of psychotherapy, as well as the wider use of antidepressants and other drugs to treat many mental disorders. But the study's results, they said, also indicated that despite these changes, access to psychotherapy had increased for some groups, and that talk therapy remained, for many people, an important component of mental health treatment.

"With all the attention given to antidepressants and other medications, the role of psychotherapy can be easily overshadowed," said Dr. Mark Olfson, an associate professor of clinical psychiatry at Columbia University and the lead author of the study, which appeared in this month's issue of The American Journal of Psychiatry. "But these findings make clear that psychotherapy continues to play an important role in the mental health care of many Americans."

The study, based on data collected in two national surveys by the federal Agency for Healthcare Research and Quality, is the largest to examine the patterns of psychotherapy use over time.

Dr. Olfson said that talk therapy represented a smaller part of all mental health treatment in 1997 than in 1987.

But in absolute numbers, psychotherapy's popularity remained steady, and even experienced a slight increase. In 1987, 7.85 million people - or 3.24 percent of the nation's population - made visits to mental health professionals for psychotherapy, the study found. Ten years later, that number had risen to 9.69 million, or 3.59 percent. The increase was not statistically significant, the researchers said.

In contrast, the researchers noted large increases in the use of psychotherapy among people from the ages of 55 to 64, a little over 836,000 or 3.92 percent of whom received psychotherapy in 1997 compared with 455,000 or 2.02 percent in 1987.