Johnny Depp, Amber Heard and when recreational substance use turns toxic

As Johnny Depp and Amber Heard rehash their ill-fated marriage in court, the public is hearing each of their perspectives on how the relationship Depp initially called "too good to be true" spiraled. And much of the media attention has focused on a potential contributing factor to the demise of their marriage: drinking and drug use.

In the past, Depp has been candid about his addiction to prescription pain medication. But during the trial, intimate details about his recreational drug use were brought to the light. The "Pirates of the Caribbean" actor acknowledged his history with alcohol, cannabis and cocaine. And during her testimony on Wednesday, Heard said she took mushrooms and MDMA during their relationship.

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These admissions raise questions about the role drug-use played in their tumultuous, allegedly abusive marriage. Experts specializing in addiction say that Depp and Heard are just one example of how substance use and toxic relationships often go hand-in-hand.

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How substance use can contribute to a toxic relationship

When it comes to marriage and addiction, it's a chicken-and-the-egg dilemma. On the one hand, frequent alcohol and drug use can take an emotional toll on even the strongest relationship by influencing unhealthy behaviors like deception, manipulation, isolation or aggression.

"I'm not saying drugs alone will create a whole new different personality, but anything that's repressed or unaddressed can come out under the influence," explains Lin Sternlicht, an addiction specialist and family advisor. "Alcohol and certain drugs may amplify what's already going on inside, so if you're frustrated or unhappy with your partner, you may feel more impulsive to act out on these negative feelings."

But simultaneously, a stressful and unhealthy marriage can also fuel addictive tendencies and trigger relapse.

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"If the relationship is built on the rituals of using, then it's an indication that there are problems deeper in the relationship, as well as problems in substance abuse," says Robert Navarra, a certified therapist and addiction counselor.

It becomes more complicated when both partners use drugs together as a way of coping or bonding. While it may seem fun or therapeutic in the moment, there are long-term consequences.

Sachi Ananda, a clinical sexologist specializing in addiction recovery, says depending on an external stimulant can limit your libido and energy levels, resulting in sexual dissatisfaction.

"When you ingest a party drug, you're changing the reward center in your brain, which controls what it takes for you to feel pleasure. So now your threshold for pleasure is exponentially higher … and it becomes hard to naturally achieve that high with your partner, and the feeling won't compare to how it feels with the drugs."

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The dangers of party drugs, social drinking

Separate from his opiate addiction, Depp acknowledged he did "a line or two" of cocaine with Heard's sister as well as Marilyn Manson. Heard also said she took "a capsule" of MDMA during an argument with Depp.

According to the National Institute on Drug Abuse, cocaine and MDMA, also called "club drugs," are considered stimulants and tend to produce temporary euphoria. Research has shown that consuming them, even in moderation, can produce a wide range of concerning effects, including heightened anxiety, paranoia, irritability, seizures, increased blood pressure and, in some cases, death. Even one-time use can result in withdrawal symptoms, according to Sternlicht.

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"Just because it's common and 'socially acceptable' doesn't make it normal or healthy," she warns. "Coming down from MDMA and cocaine is distressing, and people usually feel very unpleasant symptoms like confusion, drowsiness, aggression or depression."

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Depp said on the stand he tried to detox and stay sober for the sake of his marriage.

During her testimony, Heard said she was "against (Depp's) drinking, supportive of sobriety," but she said she did drugs with him in an attempt to be "the good cop" and "the fun girlfriend." Depp testified Heard rejected his idea she stop using illicit substances as he worked on his sobriety.

Kenneth Leonard, director of Clinical Research Institute on Addictions and professor of psychiatry at the University of Buffalo, says that treatment for couples who use drugs together can be tricky and often requires both parties' willingness to change. One of the most important pillars of recovery is surrounding yourself with those who support your new way of living, which may involve changing your social group or cutting out friendships primarily based on drinking and drugs.

However when there's a discrepancy in the relationship regarding drug usage, the result is usually temptation, relapse or resentment.

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"It's very hard to be successful in abstaining or reducing your drug use when your partner does not," Leonard says. "Whether it's alcohol, cannabis or opiates, the cues to those drugs will always be in your presence if your spouse is still using, and it makes it much more difficult to resist. The pressures to manage that would undoubtedly create problems in the relationship."

As a couples counselor specializing in addiction, Navarra says that both the individual and the couples treatment are important for recovery.

"People need to recover on their own, but it's crucial for the couple to get help together to look at the impact of this disorder on partner 1, partner 2 and the relationship," he says. "If we can assist a couple to transition from active addiction to active recovery, that decreases the likelihood of relapse."

If you or someone you know is struggling with substance abuse or addiction, you can call the Substance Abuse and Mental Health Services Administration National Helpline at 800-662-HELP (4357) any time of day or night.

This article originally appeared on USA TODAY: Johnny Depp, Amber Heard trial: when recreational drug use turns toxic