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.