Bennett A. Brown, who was named president and chief executive officer of Citizens & Southern National Bank in Atlanta on Tuesday, said yesterday that the bank's current troubles date back to the 1960s.

"It looked like the growth in the real estate market would never end," Brown said during a telephone interview from Atlanta. "We (C&S) became overly aggressive. We wanted to take the lead . . . and it has taken us this long to bail out."

Brown, 48, was assistant to the president. He replaced Richard Kattel, who resigned on Monday as chairman and president of C&S, the third largest bank in the Southeast with assets of $3.5 billion. At the same time, the board of directors named A. Pratt Adams, a senior partner in a Savannah law firm, chairman of the bank.

C&S recently eliminated its dividend for the first time in its 71-year history when it reported profits for 1977 of $3.2 million, down from $14.5 million a year earlier.

But it turns out that C&S did even worse in 1977. Concurrent with Brown's appointment, this week the bank restated its 1977 financial results to show a net loss of $7.8 million instead of the profit of $3.2 million.

"We decided to restate and get all the bad news out of the way in 1977," said Brown, who predicted that the bank "definitely will make a profit in 1978."

The loss is a result of the decision, announced this week, to impose an additional charge of $15 million ($11 million net) against 1977 pre-tax earnings -- $10 million of additional real estate in write-downs and $5 million for additional loan loss reserve provisions.

"We think we have a very generous loan loss reserve now," said Brown. C&S has $42 million in reserves, which equals 2 percent of loans outstanding, while other banks have reserves of about 1 1/4 to 1 1/2 percent, Brown noted.

But C&S still has some hurdles to jump on its way to recovery. For example, C&S announced that the content of the opinion rendered on the upcoming 1977 annual report by its accountant, Haskins & Sells, will depend on two events -- the previously announced investigation by the Securities and Exchange Commission of the relationship between the bank and the real estate investment trust that it manages, and the ability of that ailing REIT, C&S Realty Investors, to come up with new financing.

Brown blamed Atlanta boosterism and the general swing of the economy for C&S's woes. "If the anticipated growth of Atlanta had continued, we would have been OK," he said. But Atlanta has been hit hard as any metropolitan area in the country."

Brown's appointment as chief executive officer may be temporary. The board also appointed an executive committee to search for a new chief executive -- and Brown is among the candidates being considered for the top job.