So much for the younger demo....

The LA Times reports that Prime-time TV is going gray.

After decades chasing young viewers, the broadcast networks are starting to shift tactics — peppering their lineups with shows and actors who appeal to the growing audience of aging baby boomers.

"The Millers" on CBS features 72-year-old Beau Bridges and Margo Martindale, 62. NBC has James Spader, 54, in "The Blacklist" and is considering a new family sitcom with Bill Cosby, 76. ABC, stuck in last place, is developing a show about basketball buddies in their 60s.

The trend is being driven by demographics. Members of the baby boom generation will all be 50 or older this year, and they watch a disproportionate amount of TV.

The median age of a broadcast television viewer is now the highest ever at 54. Twenty years ago, it was 41. The most-watched scripted series in the 1993-94 season was "Home Improvement," with a median viewer age of 34. Today, it's "NCIS," with a median viewer who is 61.

Confronted with these realities, the networks are aggressively making the case to advertisers that older viewers are valuable — especially the affluent and influential 55-to-64-year-olds they're calling "alpha boomers." The 50-and-up crowd of today, they contend, is far different than the frugal and brand-loyal group that came of age during the Great Depression and World War II.

"These people are more active, healthier and much more likely to still be in the workforce," said David Poltrack, chief research officer at CBS. "It's certainly a much more vibrant and economically active audience than it used to be."

Ironically, it was the baby boomers who first led TV networks to cater to younger viewers in the 1960s.

Until then, network ad rates were based simply on the number of households watching. But as the first wave of Americans born after World War II entered adulthood, third-place network ABC saw an opportunity to promote this audience as super consumers, and pushed for advertisers to focus on viewers younger than 50.

By the 1970s, ABC was booming with youth-oriented hits such as "Charlie's Angels" and "Happy Days."

Now CBS, NBC and ABC are pointing to research that shows consumers over 50 spend some $90 billion a year on cars alone. By 2017 they will control 70% of the nation's disposable income.

"Boomers have been marketed to since they were 5, because they were the first generation raised in front of the TV," said Matt Thornhill, founder of the marketing think tank the Boomer Project.

In contrast, their children, known variously as millennials, Gen Y or echo boomers, are living at home longer and making fewer key purchasing decisions than their predecessors.

In theory, that should make them less attractive to advertisers. But in reality, they are more prized than ever.

Younger adults, busy with school, careers, socializing and child-rearing, have always watched less TV. Now they're even harder to find, thanks to technology that allows them to watch TV whenever and wherever they want, and to skip over commercials.

Since these viewers are so elusive, advertisers will pay more to reach them.