Alongside hallucinations and delusions, Miotto says methamphetamine can induce traits similar to obsessive-compulsiveness called "tweaking" on the streets.
In Cross it appeared as writing, in others it shows up as the need to constantly pick things apart and try to put them back together -- usually unsuccessfully.
"If you ask police, they'll tell you 'we can tell it's a meth house because the washing machine is taken apart in the front yard,'" Miotto said.
Even if a methamphetamine user gets treatment for his or her addiction and recovers without a permanent psychosis, depression may soon follow.
Stimulants like methamphetamine deplete dopamine, which is the primary chemical in the "reward pathway" of the brain, Miotto says.
"There is also a theory that drug abuse "resets" the reward pathway, making it more difficult to experience reward or well-being from normally pleasurable experience, Miotto says.
Unfortunately, Cross did not escape this part of methamphetamine addiction.
"I'm not the same person, I can tell you that," said Cross, whose biggest regret was the time drugs took away from her five young children.
"I was a fun-loving person," she said. "I suffer now more from depression."
Meth users make up only 0.3 percent of the U.S. population, according to the 2006 National Survey on Drug Use and Health.
But the 8 percent of people who use other drugs aren't necessarily free from permanent mental health affects.
In the summer, a study in the journal Lancet found that marijuana can increase an individual's risk of developing a psychosis by 40 percent, and possibly up to 200 percent, depending on how long and how much a person used.
The greater a person's risk to develop a psychosis like schizophrenia, the more dangerous it is to use marijuana.
Marijuana may also exacerbate an underlying mood disorder like anxiety, depression or bipolar disorder.
"Those are often the chicken-and-the-egg questions: If people who have depression or anxiety -- symptoms of a mood disorder -- are more likely to use marijuana in the first place," Miotto said.
For Jim Morrison, 55, the question of the chicken or the egg may never be answered. He started using marijuana at 16 and was diagnosed with bipolar disorder at age 40.
Morrison, the webmaster of the addiction support Web site, mysobrietyspace.com, has been sober for 28 years. But for the better part of a decade, his drug use came with emotional mood swings and occasional paranoia.
"Once I quit drinking or getting stoned, the manic depression episodes got much better,"Morrison said.
At one point in 1979, Morrison became so paranoid about his drug use that he was convinced the Newport Beach, Calif., SWAT team was waiting at his apartment to bust him for an ounce of marijuana.
He parked his cars two blocks from his apartment, hid his stash in an Los Angeles Times newspaper and laid still in the dark for the rest of the night.
"I was thinking, 'oh wow, I beat them,'" he said. The next morning, he realized he'd thrown away his stash along with the newspaper.
"I went flying down the stairs in my underwear and jumped into the Dumpster and found it," Morrison said. When a neighbor caught him in the Dumpster, he realized the marijuana was causing too much trouble. "That's the precipice of insanity."
Cross, who is a frequent user of Morrison's Web site, agrees. She's currently worried about a friend at risk for schizophrenia who's also using methamphetamines.
"It's the luck of the draw and are you willing to gamble? Because it does mess up your mind and some people don't snap out of it," she said.