How often do adults who come in for depression actually have undiagnosed ADHD underneath?

While ADHD and depression can overlap, research suggests this overlap is less common than it is often portrayed. Having said that, the figures of comorbid ADHD and depression are slightly higher than the prevalence of ADHD in the general adult population, suggesting that undiagnosed ADHD is more common among adults with depression and related complaints. Prevalence can also vary depending on the population being studied. Part of the clinical confusion is that depression itself can cause poor concentration, low motivation, mental fog, and low energy, which can look similar to ADHD. A key difference is that ADHD is lifelong and usually starts in childhood, whereas attention problems related to depression tend to start later and improve as mood improves. Untreated ADHD—especially the inattentive and executive function difficulties—can erode self-esteem, increase frustration, and lead to chronic stress, which can contribute to or exacerbate depressive symptoms. It is also common for anxiety and mood symptoms to mask or overlap with ADHD, making the underlying attention regulation difficulties less obvious at first glance.