The 28-year-old singer took to Twitter to share his love for the 25-year-old star - who was rushed to hospital on Tuesday (24.07.18) following a suspected overdose - and insist she is ''strong''.
Joe - who briefly dated Demi in 2010 and has remained close friends with her - tweeted: ''Like all of you I am thinking of @DDLovato right now. She needs our prayers and support. We all know how strong you are Demi. #prayfordemi (sic)''
His brother Nick Jonas - who starred alongside Demi in 2008 Disney movie 'Camp Rock' - echoed his sibling's thoughts.
He wrote on Twitter: ''Like all of you I am reeling at the news about Demi. All of us love her and need to pray for her to get well. She is a fighter. #prayfordemi (sic)''
The pair's brother Kevin Jones tweeted: ''Sending my prayers and thoughts to @ddlovato and her family right now. (sic)''
Several other stars have also sent well wishes to Demi, who was initially thought to have been hospitalised following a heroin overdose, but a source close to the singer has told TMZ that is not the case.
Ariana Grande wrote on Twitter: ''i love u @ddlovato (sic)''
Lady GaGa tweeted: ''We should all wrap our arms of love around Demi Lovato. I am so happy you're alive. Thank God. If I know my monsters as well as I believe I do, we all wish you self-compassion and inner peace. And may you receive the love so many have for you. #ImConfidentInDemi Demi, I love you. (sic)''
Brad Paisley - who collaborated with Demi on 2016 song 'Without A Fight' - praised Demi as the most ''honest'' and ''brave'' woman he has met.
He wrote: ''My friend @ddlovato is one of the kindest, most talented people I've ever met. Praying for her right now, addiction is a terrifying disease. There is no one more honest or brave than this woman. (sic)''
Demi has previously sought treatment for addiction after battling with the condition for several years.
She is now ''awake and with her family'' at the Cedars-Sinai Medical Center in Los Angeles.
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