Predicting impact and longevity is a tricky endeavor. The Conners’ Adult ADHD Rating Scales (CAARS™) was originally published in 1999, a year that also witnessed global threats that quickly fizzled (the “Y2K” computer bug), surprisingly durable political transitions (Vladimir Putin assumes the Russian presidency), the arrival (Serena Williams) and departure (Wayne Gretzky) of legendary talents, some technical innovations that ascended mightily before being displaced (Blackberry devices, DVDs) and others that defied dismal “expert” prognostications to achieve enormous, enduring success (PayPal). So, it was with considerable enthusiasm but uncertain expectations that we, along with our revered mentor (Dr. Conners) and forward-thinking publisher (MHS), released the CAARS with the hope that it would become a valued tool in the comprehensive assessment of ADHD in adults.

By the end of the 1990s, the need for such a tool had become obvious. Over the preceding years, coincident with the realization that ADHD was not typically “outgrown” in adolescence, we had seen rapidly increasing numbers of men and women presenting for evaluations at the ADHD clinic directed by Dr. Conners at Duke University’s Medical Center. Our efforts to meet this growing clinical demand were hampered, however, by the lack of a well-normed, psychometrically-sound, ADHD-specific rating scale to complement the information provided by diagnostic interviews, clinical observation, historical records, and computer-based vigilance tests. Having pioneered the clinical use of behavior rating scales with children, Dr. Conners was ideally positioned to spearhead the development of similar scales for adults. Moreover, his standing as a renowned expert on ADHD undoubtedly made clinicians, researchers, and pharmaceutical companies more receptive to incorporating the resulting CAARS as part of their assessment protocols. Although pleased by its favorable reviews and high adoption rates, we certainly never anticipated that the original CAARS would remain widely used more than two decades after its release (an outcome eliciting surprise and gratitude in equal measure).

Nevertheless, all good things, as they say, must come to an end, and the CAARS has clearly passed its “use by” date. The item pool we drafted in the late 1990s does not adequately reflect the significant progress made in our scientific understanding of ADHD in adults, current DSM criteria, or increased attention to constructs such as executive dysfunction, motivation deficits, and emotional dysregulation. Larger and more representative standardization samples were needed to produce norms that better reflected the dramatic demographic changes occurring in the North American population over recent decades. Statistical advances called for the construction of a more sophisticated scale with greater power to (a) discriminate individuals with ADHD, both from the general population and from those with other clinical disorders; (b) fairly assess individuals across a range of demographic variables including race/ethnicity, gender, and educational level; (c) more accurately assess older adults; and (d) detect different response styles that might impact the validity and/or interpretation of results. The CAARS 2, detailed in this manual, addresses all of these needs while providing numerous other enhancements to the original CAARS, including updated Content and DSM Symptom scales, items addressing the critical domains of impairment and functional outcome, screening items for other clinical concerns (viz., depression, anxiety, suicidality, self-injurious behaviors), the availability of multiple reference samples, newly constructed versions of the ADHD Index and short form, gender-neutral language, Spanish- and Canadian-French translations, more customizable and user-friendly automated reports, and alignment with the Conners 4 to facilitate the assessment of ADHD across the life span. As a state-of-the-art, psychometrically-sound measure that maintains the clarity and accessibility of its predecessor while recognizing the multifaceted complexity of adult ADHD, the CAARS 2 is a tool that we hope facilitates the accurate, comprehensive, multi-method, and multi-informant assessment of ADHD in adults for years to come.

A comprehensive, “from the ground up” revision of a clinical rating scale is a complex, multi-year endeavor requiring the carefully staged synergistic efforts of many talented and motivated professionals. Fortunately for us, that is exactly what MHS provides as a publisher. Consequently, we are immensely grateful to Steve and Rodeen Stein for their vision, conscientiousness, and unwavering commitment to quality; to Hazel Wheldon and Jenni Pitkänen for their benevolent oversight and steady support; to Gill Sitaranios, Joanna Solomon, and Heather Clark for their truly impressive statistical acumen (and equally impressive ability to explain their magic to Muggles); to Lindsay Ayearst for her keen sense of where the field is and where it’s headed; to Diane Mangalindan and Gelareh Jowkar for their ability to immerse themselves in the weeds of this project and re-emerge intact and ready to provide the essential executive functions that enabled us to know where we’d been, where we needed to go, and what needed to be done to get us there; and, in particular, to Sara Rzepa for her tireless efforts in leading our team and remarkable skill in balancing our highest ideals for what this scale could be with the practical realities of budgets, staffing, deadlines, and the like. We also owe a debt of gratitude to the data collection coordinators and thousands of individuals who generously provided the data without which this revised scale could not have been realized.

Finally, it is bittersweet to have reached the finish line without Keith Conners, who passed away in 2017. Keith possessed that rare, deep understanding of ADHD that can only result from the combined effects of a command of the relevant scientific knowledge base (a portion of which he was responsible for producing), decades of clinical work, and a healthy dose of humanism. We’re honored that the CAARS 2, along with the other MHS assessment measures that bear his name, continues his legacy of impactful and enduring contributions to the field. We’re also forever grateful for the critical role his modeling and mentorship played in enabling and shaping our careers

Drew Erhardt, Ph.D.
October 2023

Elizabeth P. Sparrow, Ph.D.
October 2023