Lunch rush was over, but distractions remained numerous inside the La Bou cafe just off Highway 49 in Auburn. Blenders whirred out smoothies every few minutes, laughter erupted from a nearby group, a young worker noisily cleared tables.

Yet, through it all, Cass Brown Capel stayed focused – eyes locked on her interviewer, the need to interject random thoughts stifled, attention not straying to her daughter, Ariana, who was sitting placidly next to her.

You would have no inkling that Capel, a 54-year-old psychologist from Auburn, has been diagnosed with the adult version of attention deficit/hyperactivity disorder since 1991.

That is, until you looked down at her hands, busy rolling and unrolling a paper soda straw wrapper between her thumb and index finger until it became a pulpy mess.

"I just like the way it feels," Capel says. "It's a habit."

It's such a habit, in fact, that Capel shows off a thick callous on the underside of the middle joint of her right thumb.

"They took an X-ray and turns out there's a bone spur here and here," she says, pointing to her thumb and tip of her index finger. "I'm always moving. If it's not this, it's foot wiggling."

Signs of ADHD in adults such as Capel often can be subtle and misconstrued, experts say. In children, the preponderance of symptoms are related to hyperactivity and impulsive behavior. In adults, the symptoms are often inattentiveness or a combination of impulsiveness and inattentiveness.

Of the 10 million U.S. adults (4.4 percent of the population) diagnosed with attention deficit disorder, only 11 percent have sought treatment in the past year, and only 25 percent were ever diagnosed with the psychiatric condition before age 18, according to survey data from the World Health Organization.

As late as the mid-1990s, despite a spate of best-selling books on the subject, hardly any adults were diagnosed. The reason, posits Dr. David W. Goodman, director of the Adult Attention Deficit Disorder Center in Luthersville, Md., is that the manifestations mirror other conditions, such as anxiety and depression.

"Children are typically diagnosed because of disruptive behavior," Goodman says. "(Adults) that have inattention often get missed until their academic or life demands exceed their ability to compensate. They get diagnosed later in life because of disorganization, inattention, inefficiency and difficulty juggling multiple responsibilities."

Consequences stemming from a late diagnosis in adults are many: negatively affecting relationships, family and work life. A WHO report released in May found that adults with ADHD on average miss more than three weeks per year in workplace productivity due to forgetfulness, lack of concentration and impulsiveness.

"They also are twice as likely to get divorces, three times as likely to be involved in criminal activity," Goodman says. "They are highly impulsive, and half have or have had a history of alcohol or substance abuse."

Yet many mental health practitioners will not immediately think of ADHD as the cause, says Dr. Julie Schweitzer of the UC Davis M.I.N.D. Institute in Sacramento.

"We have to assess for anxiety, depression and every other potential psychiatric disorder," she says. "It takes a lot of work. We have to have some evidence it was prevalent since childhood."

It can take some detective work. Capel, diagnosed at age 37 in 1991, says she has her husband, John, to thank. Capel says her life wasn't in a shambles before then. But she hadn't reached her potential.

She wanted to be a psychologist since her undergraduate days at the University of Florida but could never muster the discipline to follow through on it. At the time she met John in the late 1980s, she had a master's degree and was working as an adolescent counselor at a residential treatment center in the Sacramento area.

"I wondered, 'Why can't I clean my room?' I'd have friends come over and give me the pretty color-coded file folders and the pens. I even had an empty file cabinet. But I couldn't get all my files in there.