Kid Cudi’s advocacy for mental health awareness and candidness about his own struggles with depression have opened a dialogue about mental illness and treatment. The Cleveland-bred rapper’s story has been so impactful that he’s even quoted in a psychology textbook.

A fan brought Cudi’s attention to his unknown contribution to Fundamentals of Abnormal Psychology on Twitter. The student thanked Cudi for the public awareness he has brought to mental health and treatment options.

“I was reading my psychology textbook and i see your picture [Kid Cudi],” the Twitter user wrote. “You have impacted and brought great awareness to Depressive and Bipolar Disorders and how treatment actually works. You have gave many people hope and made many feel like they’re not alone grateful for u man.”

Cudi responded to the tweet, writing, “Wow this is awesome!! Grateful for u too! Thanx for ridin w me all these years!”

The textbook’s excerpt about Cudi refers to the rapper checking himself into a rehab facility in 2016 due to his depression and suicidal urges. The book also quotes the message he wrote to fans on Facebook about his decision to admit himself into treatment.

“I am not at peace. I haven’t been since you’ve known me,” he had posted at the time. “If I didn’t come here, I would’ve done something to myself. I simply am a damaged human swimming in a pool of emotions everyday of my life. Theres a raging violent storm inside of my heart at all times. Idk what peace feels like. Idk how to relax.”

“My anxiety and depression have ruled my life for as long as I can remember and I never leave the house because of it,” he continued. “I cant make new friends because of it. I don’t trust anyone because of it and Im tired of being held back in my life. I deserve to have peace.”

After spending a month in treatment, Cudi went on to release his Passion, Pain & Demon Slayin’ LP, returning two years later with his Kanye West-collaborated project, Kids See Ghosts. Back in May, the rapper announced he’d be dropping new music this year.