When diagnosing ADHD in young adults emphasize informant reports, DSM items, and impairment.
Sibley MH, Pelham WE, Molina BSG, Gnagy EM, Waxmonsky JG, Waschbusch DA, Derefinko KJ, Wymbs BT, Garefino AC, Babinski DE, Kuriyan AB. When diagnosing ADHD in young adults emphasize informant reports, DSM items, and impairment. J Consult Clin Psychol. 2012 Dec; 80(6):1052-1061.