Vyvanse and Sluggish Cognitive Function : Can It Help?

ADHD is well-known for symptoms like distractibility and impulsivity, but there’s another set of cognitive difficulties that some people experience—what researchers call Sluggish Cognitive Tempo (SCT). While SCT isn’t an official diagnosis, it describes a pattern of symptoms like frequent daydreaming, mental fog, slow information processing, and low energy. Many people with ADHD report these struggles, but whether SCT exists as a separate condition is still debated.

A recent placebo-controlled study explored whether Vyvanse (lisdexamfetamine)—a common ADHD stimulant—could help adults who have both ADHD and SCT symptoms.

What Did the Study Find?

The trial included 39 adults with ADHD and SCT. Each person went through two four-week treatment phases—one on Vyvanse and one on placebo—with a break in between. Researchers tracked changes in both ADHD symptoms and SCT symptoms using structured rating scales.

Key results:

• Vyvanse significantly improved ADHD symptoms across both treatment phases.

• SCT symptoms improved only in the first phase, suggesting either a real benefit or a possible carryover effect that made later comparisons unclear.

• When participants switched from Vyvanse to placebo, their SCT symptoms didn’t fully return to baseline, raising questions about long-term effects.

Side effects were generally mild and in line with what’s expected from stimulant medications—appetite loss, headaches, and occasional anxiety.

What Does This Mean for ADHD Patients with SCT?

For people who struggle with both ADHD and SCT symptoms, stimulant treatment—especially amphetamine-based options like Vyvanse—may be beneficial. While more research is needed, this study suggests that SCT-related symptoms might also respond to medication, not just traditional ADHD symptoms like inattention and impulsivity.

That said, since SCT isn’t a formal diagnosis, it’s important not to over-label cognitive sluggishness as a separate condition. Instead, the focus should be on treating functional impairments, whether they stem from classic ADHD symptoms, executive dysfunction, or difficulties with mental processing speed.

If ADHD treatment alone isn’t fully addressing cognitive fog, slow thinking, or persistent mental fatigue, it may be worth discussing options with a healthcare provider. While SCT remains a debated concept, medications like Vyvanse could offer real benefits for those who experience these symptoms alongside ADHD.