Forget the notion that economic downturns only hurt lower and middle-class consumers. The affluent are definitely battening down the hatches and buttoning up their Birkins, said a new study by Unity Marketing.

According to the market research firm’s ”Luxury Consumption Index,” luxury consumer confidence has never been lower.   

“Luxury consumers have lost the impetus to spend,” said Pam Danziger, founder of Unity Marketing.  “The idea that one group of people is going to be completely immune to the effects that are happening in another segment of the market … it’s an illusion.”

The firm’s index of luxury consumer confidence fell to 63.6 points in the fourth quarter, down 27 percent, from 87.4 points in the third quarter.

“The number one thing that dragged down the index is this lack of confidence in the economy as a whole and its leadership,” Danziger said.

Their actual spending has slowed as well.

Luxury consumers spent an average of $24,301 on things like yachts, fancy cars, spa treatments, house keepers and deluxe vacations in the second half of 2007, Danziger said. That’s down from $29,307 in the first half of the year.

In the fourth quarter, spending on high-end home goods was down 24 percent, while spending on luxury experiences like dinners and spas was down 25 percent, Danziger said, while spending on “personal luxuries” like handbags and clothing rose.

“Clothing is a more affordable luxury than buying a new sofa and a plasma screen TV,” Danziger said.