Sobriety has helped Miley Cyrus make full use of therapy by examining the impact her parents’ upbringings have had on her own mental health.The Wrecking Ball hitmaker gave up alcohol and drugs more than six months ago following “big” vocal cord surgery back in November after she was initially hospitalised for tonsillitis.And turning her back on her love of marijuana and booze has allowed Miley to view things in a different light.