For the first time in its 127-year history, the American Psychological Association has issued guidelines to help psychologists specifically address the issues of men and boys — and the 36-page document features a warning.

“Traditional masculinity ideology has been shown to limit males’ psychological development, constrain their behavior, result in gender role strain and gender role conflict and negatively influence mental health and physical health,” the report warns.

The new “Guidelines for the Psychological Practice with Boys and Men” defines “masculinity ideology” as “a particular constellation of standards that have held sway over large segments of the population, including: anti-femininity, achievement, eschewal of the appearance of weakness, and adventure, risk, and violence.” The report also links this ideology to homophobia, bullying and sexual harassment.

The new guidelines, highlighted in this month’s issue of Monitor on Psychology, which is published by the APA, linked this ideology to a series of stark statistics: Men commit approximately 90 percent of all homicides in the U.S., they are far more likely than women to be arrested and charged with intimate partner violence in the U.S., and they are four times more likely than women to die of suicide worldwide.

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Jared Skillings, a psychologist and the APA’s chief of professional practice, told NBC News these new guidelines are intended to educate mental health professionals about the unique issues facing this patient population. The APA published a similar report about girls and women in 2007 and is expected to publish an updated version this year.

"Masculinity ideology,” Skillings said, was important to highlight because it “represents a set of characteristics that are unhealthy for men — men who are sexist or violent or don’t take care of themselves.”

The report addresses the “power” and “privilege” that males have when compared to their female counterparts, but it notes that this privilege can be a psychological double-edged sword.

“Men who benefit from their social power are also confined by system-level policies and practices as well as individual-level psychological resources necessary to maintain male privilege,” the guidelines state. “Thus, male privilege often comes with a cost in the form of adherence to sexist ideologies designed to maintain male power that also restrict men’s ability to function adaptively.”

The report argues that some of the psychological and social problems that disproportionately affect men may be in part because they are “less likely to be diagnosed with internalizing disorders such as depression, in part because internalizing disorders do not conform to traditional gender role stereotypes about men’s emotionality.” Men, the report adds, are more likely to be diagnosed with "externalizing disorders," like attention deficit hyperactivity disorder (ADHD), which often relies on medication instead of psychological intervention.

The guidelines for psychologists outlined in the report include encouraging them to "recognize that masculinities are constructed based on social, cultural, and contextual norms"; "understand the impact of power, privilege, and sexism on the development of boys and men and on their relationships with others"; and "reduce the high rates of problems boys and men face and act out in their lives such as aggression, violence, substance abuse, and suicide."

Skillings said parents can play a part, too. He recommended they let their boys know, “It’s OK to not be OK all the time.”

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