Lisdexamfetamine improves outcomes of adults with ADHD, sluggish cognitive tempo

Lisdexamfetamine significantly improved outcomes among adults with ADHD and comorbid sluggish cognitive tempo, according to results of a crossover trial published in Journal of Clinical Psychiatry.

“The current study is a part of a two-phase (phenotypic and treatment) examination of [sluggish cognitive tempo (SCT)] and ADHD at two academic centers (NYU Grossman School of Medicine and Icahn School of Medicine at Mount Sinai),” Lenard A. Adler, MD, of the department of psychiatry at the NYU Grossman School of Medicine, and colleagues wrote. “The phenotypic phase characterized SCT, ADHD and [executive function] symptoms in subjects who had ADHD and SCT versus those who had ADHD and were SCT negative. An interim report of the NYU cohort seen in that study found that, similar to prior studies noted above in children and adults, individuals with both SCT and ADHD, versus adults with ADHD alone, have higher levels of inattentive symptoms and impairment.”

For the current crossover trial of lisdexamfetamine (LDX) vs. placebo, the researchers recruited participants who had both ADHD and SCT in the phenotypic phase. They aimed to determine the efficacy of LDX among adults with ADHD and SCT on the nature and severity of their ADHD symptoms and SCT behavioral indicators. Between January 2016 and April 2018, they recruited 38 adults who had DSM-5 ADHD, determined via the Adult ADHD Clinical Diagnostic Scale v1.2, and SCT at the two aforementioned academic medical centers. At baseline and weekly during treatment, they evaluated participants for symptoms of ADHD, SCT, executive function deficits and functional impairment. Participants received 4 weeks of treatment with either LDX 30 mg to 70 mg or matching placebo with a 2-week washout prior to switching to the other arm. Coprimary outcome measures included the ADHD Rating Scale and Barkley Adult ADHD Rating Scale-IV SCT subscale.

Results showed moderately large treatment effects for LDX compared with placebo on SCT ratings in both treatment periods. These effects achieved significance only in block one because of carryover effects of the first treatment epoch into the second. The researchers also observed significant effects for LDX over placebo in ADHD, executive function deficit and functional impairment ratings, without order effects. Moreover, they found no site differences, except on the Global Executive Complex score of the Behavior Rating Inventory of Executive Function-Adult Version. Sex, age, race and ethnicity appeared to have no moderating effects.

“This is the first study to find treatment effects of stimulants on SCT behavioral attributes in adults with ADHD and SCT,” Adler and colleagues wrote. “Future trials should examine potential mitigating effects of [executive functional deficit] symptoms on response and should be conducted with parallel designs to mitigate any potential for carryover effect. Additionally, the responsiveness of SCT in other conditions or as standalone disorder to ADHD treatments remains a potential line of investigation.”