CHICAGO (AP) — The deaths of celebrity chef Anthony Bourdain and fashion designer Kate Spade highlight a troubling trend — rising suicides among middle-aged Americans.

Mental health problems, often undiagnosed, are usually involved and experts say knowing warning signs and who is at risk can help stop a crisis from becoming a tragedy.

Bourdain, 61, and Spade, 55, died three days and a continent apart this week amid a new U.S. report showing an uptick in suicides rates in nearly every state since 1999. Middle-aged adults — ages 45 to 64 — had the largest rate increase, according to the report from the Centers for Disease Control and Prevention.

Previous studies have suggested economic downturns and the nation's opioid crisis contributed to the rise in middle-aged suicides.

Dr. Christine Moutier, a psychiatrist and chief medical officer for the American Foundation for Suicide Prevention, said Friday it's important for everyone to know the warning signs and to intervene when family members, friends or co-workers appear troubled. Asking if they've had suicidal thoughts is not harmful and lets them know you care, she said.

Behavior that may indicate someone is suicidal includes:

—Talking about feeling hopeless, trapped, a burden to others or wanting to die.

—Unusual mood swings or withdrawing from family, friends and usual activities.

—Giving away important possessions.

—Increased use of alcohol or drugs.

This week's report found that many suicides were in people with no known mental illness. But Dr. Joshua Gordon, director of the National Institute of Mental Health, said that contradicts years of data, suggesting many have "gone undiagnosed and untreated. It's very troubling."

Gordon said doctors need to ask patients at every opportunity about their mental health and evaluate their risk for suicide.

"When you ask everybody and not just people you might suspect, you double the number you detect," he said.

Gordon noted that psychotherapy and certain psychiatric drugs have been shown to reduce suicidal tendencies.

Moutier of the American Foundation for Suicide Prevention, said that suicides can be "contagious" — hearing about one may make others who are already at risk turn to self-harm. She said celebrity suicides also typically prompt an increase in calls to suicide help lines.

"People should know that suicide is preventable. Anyone contemplating suicide should know that help is available, and that there is no shame in seeking care for your mental health," Dr. Altha Stewart of the American Psychiatric Association said in a statement.

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Follow AP Medical Writer Lindsey Tanner on Twitter: @LindseyTanner . Her work can be found here .

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