I was the first person to suspect something was wrong. I was home for Thanksgiving that year and noticed that my sister wasn't herself.

Everyone else was used to her behavior and shrugged it off. Since I lived out of town and saw large changes during my occasional visits instead of steady small ones every few days, I realized that something wasn't right.

It started with the maniacal laugh. I asked Dena what she was laughing at, but she wouldn't say. It was unnerving to see her in her own little secret world like that.

When she came for a visit and told me that my grandfather was dying of cancer and no one wanted to tell me, I didn't know what to think.

She clearly believed what she was saying, yet it didn't seem like something my family would do. I grew uncomfortable in Dena's presence, and even more so when my parents assured me that Grandpa was completely healthy.

My parents wanted to believe she was fine, but when she had her first psychotic episode, it was clear something wasn't right.

Several other psychotic episodes, brief hospital stays and a roller-coaster ride later, we were able to get Dena to admit herself to a nationally recognized psychiatric hospital. It was there that we got a diagnosis, though when it comes to mental illnesses, it's never 100 percent.

The words "schizo-affective disorder" were scary but explained her behavior. Looking back over the years, some early signs were evident, like her tendency to rewrite personal history and believe it.

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Dena did well for a while. When she took her medication, she was the Dena we knew. But when she moved back to our hometown a few years later, she started a downhill slide. To such a fiercely independent person like my sister, the medication and the subsequent loss of total control made it harder for her to deal with her illness.

As a result, Dena would go in cycles. She took her medicine for a while and things would be tolerable. But then she got angry over small things. Her bills started piling up. Her landlord called my parents asking if she'd be able to pay rent. She missed appointments.

She showed up late for work. One time she quit a job she said she liked and didn't bother to tell anyone, including her boss. It was always clear when she wasn't taking her medicine.

I would often tell Dena that she wasn't herself when she didn't take her meds. I told her I didn't like being around her then. As sincere as my intentions were, they only fed into her paranoia. Imagine if everyone was telling you to take your medicine when you didn't trust anyone in the first place. No wonder it wasn't effective.

During all this time, she never truly accepted her illness. Because of this and because it wasn't our news to tell, almost everyone in our lives had no idea what was really going on. Most people were familiar with her lifelong tendency toward impulsive behavior and this often masked her illness. We would just tell those who noticed her shift in behavior that she was having a difficult time, maybe even that she was a bit depressed.

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The year before her death was one of the worst. She had many more bad days than good ones. Since she lived life on edge, I was always prepared for something to happen, but never dreamed it would be a car accident unrelated to her illness that would end her life so abruptly at the age of 25.

If she had come to accept her mental illness as just that, I like to think she would have been an advocate, just as she was for the other things in her life she felt strongly about. The stigma of mental illness is strong, even today. Perhaps that's what kept her from going public. I know so many people who either have battled a mental illness or have a close family member with one.

Why are so many suffering behind closed doors? According to the National Institute of Mental Health, an estimated 22 percent of Americans ages 18 and older -- about 1 in 5 adults -- have a diagnosable mental disorder in a given year. In addition, four of the 10 leading causes of disability in the U.S. are mental disorders.

Mental illnesses do not discriminate. They're unfair, cruel kidnappers. It breaks my heart to think of what Dena endured. The stigma that drives our loved ones to secrecy is harmful. It hurt my sister. It hurt her friends. It hurt my family. The veil of silence needs to be lifted.