Bipolar disorder is kind of severe by definition (mild cases are still impactful), but there's a milder version called cyclothymia or cyclothymic disorder. Depending on the person, it can be managed without medication, and a common comorbidity is ADHD.

A recent paper reads:

Cyclothymia seems to be often associated with coexisting ADHD symptoms, although this comorbidity is understudied.

The paper is called "Clinical characterization of coexisting ADHD symptoms in a sample of adults with cyclothymia: A preliminary observational study".

It says:

In our clinical sample, nearly half of cyclothymic adults present with ADHD symptoms.

That's a lot. I hope more papers come out soon.