Hot take... Bipolar Disorder (as well as its milder cousin Cyclothymia) is just a subtype of ADHD, not its own separate disease. It is essentially where a person with ADHD cycles through ADHD-I (Inattentive subtype) and ADHD-HI (Hyperactive/Impulsive subtype). Essentially the ADHD-I is mistaken for the depressive phase and ADHD-HI is mistaken for the manic phase.
The various evidence supporting this:
* There is medical evidence suggesting a close genetic overlap between the two diseases.
* There is a very strong comorbidity with 20% of people with ADHD also having some form of BD
* The symptoms of each type closely resemble the characteristics of each pole of BD, so they are easily mistaken for eachother.
I came tot he conclusion because I always thought i had some form of extremely mild BD, but doctors said no... then iw as reading the subtypes of ADHD and saw that the two subtypes resembled my own cycles where id be in one subtype or the other depending on the day (cycles over months), and then that got me thinking so i started doing research and found that there is a lot of overlap.
I am fairly convinced 100% of BD is just an extension of ADHD, just if we are talking Type II is a particularly extreme form.