Researchers in Switzerland tested three different screening instruments on adult patients at risk of attention-deficit/hyperactivity disorder (ADHD) or psychosis, and found the instruments had only modest ability to distinguish between the two conditions.
“The symptomatic overlap between these two conditions evidently makes it difficult to identify either disorder correctly and to give definitive advice on initiating specific diagnostic procedures,” wrote Salvatore Corbisiero, PhD, and co-authors from the University of Basel, Basel, Switzerland, in a recent paper in Frontiers in Psychiatry.
This “symptomatic overlap” of ADHD and psychosis includes such common features as attentional difficulties, inner tension, emotional dysregulation, and disorganized behavior. Indeed, many individuals with a high risk of psychosis have ADHD symptoms—and such symptoms might be an early vulnerability marker for schizophrenia, the authors speculated.
Because ADHD and schizophrenia are often accompanied by impairment in major life activities, “early identification of individuals with ADHD and those at risk of psychosis is imperative,” Dr. Corbisiero and co-authors stated. “Effective screening for ADHD and for symptoms of psychosis risk could reduce inadequate treatment, prolonging the suffering of patients.”
To that end, the researchers undertook this study to determine the accuracy of three different self-rating scales in screening patients at risk of psychosis or ADHD symptomatology. Two of the instruments are used to screen for symptoms of psychosis risk (Prodromal Questionnaire Brief Version and Self-Screen Prodrome) and one for ADHD symptoms (Adult ADHD Self-Report Scale Symptom Checklist).
The study involved a total of 243 patients (mostly outpatients) between 18 and 75 years old recruited from the University of Basel Psychiatric Clinics between March 2013 and August 2014.
After patients were screened with all three self-rating scales, analyses showed:
- 35.8% (87 patients) had no symptoms of psychosis risk or ADHD
- 20.2% (49 patients) had symptoms of both ADHD and psychosis risk
- 40.7% (99 patients) had psychosis risk symptoms only
- 3.3% (8 patients) had ADHD symptoms only
“The ability of the three different instruments to distinguish between patients at risk of ADHD or psychosis is found to be modest,” Dr. Corbisiero and co-authors stated. “With the instruments analyzed here, it appears difficult in a clinical sample to differentiate clearly between ADHD and psychotic symptoms.”
The reason for the shortcoming might be the difficulty of distinguishing between the somewhat nonspecific symptoms of both ADHD and psychosis risk, as well as the complexity of the symptoms of these conditions.
“There is a need for reliable and sensitive screening instruments able to clearly separate symptoms of ADHD from those of psychosis to prevent further suffering and impairments in major life activities for patients at risk of these conditions and to reduce treatment costs,” the authors concluded.
A randomized, controlled trial is needed to replicate this study, they recommended. Other psychiatric and comorbid disorders should be included in such a trial to make a more accurate assessment.