Forget being lonely or too patriotic—the real reason it's so easy to scam old people is that they become more gullible with age.

That's according to researchers at the University of Iowa, who studied a part of our brains that controls belief and doubt called the ventromedial prefrontal cortex (via ScienceDaily).

The softball-sized area sits in our heads above the eyes and deteriorates rapidly with age, making it harder to spot a scam, even it's an obvious one.

To test the theory, the UI team chose 18 patients with brain damage to the prefrontal cortex and 21 with damage outside the prefrontal cortex. Here's how their experiment worked, per Science Daily:

"Those patients, along with people with no brain damage, were shown advertisements mimicking ones flagged as misleading by the Federal Trade Commission to test how much they believed or doubted the ads ... Each participant was asked to gauge how much he or she believed the deceptive ad and how likely he or she would buy the item if it were available.

And here's what the researchers found:

"The patients with damage to the ventromedial prefrontal cortex were roughly twice as likely to believe a given ad, even when given disclaimer information pointing out it was misleading. And, they were more likely to buy the item, regardless of whether misleading information had been corrected."

There you have it: Scientific proof that old people are likely to make dubious financial decisions.

Seniors lost more than $2.9 million to scammers in 2011, a figure that would likely be higher if every instance of fraud was reported. Your Money has also reported on seniors who losing millions to toilet paper scams, backed alleged ponzi schemes, and sent money to "grandchildren" in need.

To protect loved ones from scams, click to the CFPB's Office for Older Americans and the Administration of Aging.

(H/T @adamclarkestes)