Can adhd and ocd coexist? Is it in the same way mania and depression can coexist (in bipolar disorder)? Is it really possible for someone to have both ADHD and OCD?
I was thinking that ADHD is the opposite of OCD: 1 2
from 1:

alexThePotato:
With ADHD you may be forgetful, distracted, make careless mistakes,
daydream, etc. With OCD, my impression is that you'd be very focused
on details, a bit perfectionist, and generally meticulous. So how do
they coexist, and what kind of behaviors do you attribute to each?
kukienboks:
Seems to me that OCD is about putting a lot of focus and energy into
unimportant things, something which Adhd-ers also can tend to do. The
main difference is probably that OCD-ers are driven by anxiety rather
than suffering from inability to prioritize tasks.

from 2:

There are also those who believe that OCD and ADHD often occur
together. This site on ADHD states, “It is not uncommon for someone to
have both ADHD and OCD.” I find this statement baffling, as the basic
symptoms of ADHD (listed below), in my opinion, seem to be in direct
contrast to those of OCD:
Inattention: Having a short attention span and easily distracted.
(Most people with OCD would love to be able to not pay attention to
their thoughts.)
Impulsivity: Causes a person to do dangerous or
unwise things without thinking about the consequences. (Those with OCD
do the exact opposite. They play it safe and obsess about the
consequences.)
Hyperactivity: Inappropriate or excessive activity.
(Those with OCD often go out of their way to do what they feel is
appropriate. Also, in Dan’s case, he often had very low energy as he
was “wiped out” from struggling with his OCD.)

However I read here that:

Some research has suggested that OCD and Obsessive Compulsive Spectrum
Disorders fall upon a compulsive-impulsive continuum. In other words
there exists a gradient of disorders ranging from behavioral
impulsivity to compulsivity. OCD appears to lie at one end of this
spectrum, while ADHD exists at the other.

That reminds of this picture (taken from here):

Does this then mean that ADHD and OCD together is like mania and depression together? Is there a term for the former just like the latter has bipolar disorder?

There's someone in 1 who says
&quot;ADHD makes my mind wander but then my OCD latches onto things I get so focused that nothing else exists.&quot;
and someone else who says
&quot;The OCD part of is killing me on the inside on how messy my room is. I hate messy rooms.&quot;,
but there seem to be contesting comments such as
&quot;Actual clinical OCD is so very far from the perfectionism you're describing.&quot;
and
&quot;You are confusing Obsessive Compulsive Disorder with Obsessive Compulsive Personality Disorder...I don't know if OCPD and be comorbid with ADHD, but I agree that intuitively they don't seem compatible. OCD on the other hand is sometimes misdiagnosed as ADHD (and vice versa) as they both involve problems with impulse control.&quot;
There's another comment which might explain how ADHD and OCD are not opposites, but I'm not quite sure I understand (assuming it is right):

they aren't opposites. OCD is when you have strong anxious compulsions
that you can't resist. ADHD is when you are unable to resist even weak
impulses. They harm the patient in a devilishly sinergistic manner -
let's take someone who already has difficulty resisting impulses, and
give her compulsions to do useless things!

Is it right? What exactly does that mean?
Yes, they can coexist. No, they aren't opposites. How could they be? Both ADHD and OCD affect a variety of different brain regions, and its effects are not consistent in every person. Maybe if OCD and all its symptoms were always caused by an excess of dopamine in one specific pathway in the reward system, whereas ADHD and all its symptoms was always caused by an decrease of dopamine in that same system, then they wouldn't be compatible. But this isn't the case, and it could never be the case, because the brain is more complex than that.

If mental disorders were diagnosed strictly on oppositional behaviors, then we could easily make the assertion that the opposite of being inattentive would be being hyperfocused. Therefore, nobody who has an attention deficit disorder could achieve hyperfocus, right? But we know to attribute both of these behaviors to ADHD. How can this be?

It is important to remember that mental disorders are not behaviors. OCD is marked by obsessions and compulsions, and any behaviors that may arise do so in the context of mental symptoms. It certainly follows that someone with OCD who has an obsessional focus on staying clean and organized will stay clean and organized -- in general, it is hard to not act on things that you are constantly thinking about and uncomfortable by. This is different from the child with ADHD, who may or may not have trouble staying clean and organized, because to someone who doesn't have some sort of incentive (or 'motivation'), staying clean and organized is really hard to force yourself to do on your own terms. And with ADHD, it can be all the more difficult to achieve that motivation, given the lack of dopamine and/or norepinephrine activity in certain parts of the brain.

That being said, ADHD is not a 'messiness' disorder. The behavior of an ADHD sufferer arises from a complex set of symptoms, usually related to executive dysfunction. As the name may reveal, executive functioning is an abstract yet measurable concept that encompasses a variety of higher-level processes, including regulation of focus, self-management (including keeping oneself organized), and one's capacity for paying attention to detail. Any messiness that arises from this is just an effect from the cause-and-effect relationship that is ADHD.

Likewise, OCD is not a 'neatness' disorder. OCD is marked by obsessions and compulsions. A child with ADHD may have OCD and never feel any compulsion to clean a messy room. There are many different ways that obsessions and compulsions can be demonstrated. A person with OCD may perform rituals, engage in lengthy routines, avoid certain foods, or pick at their skin. They may fear or avoid strange things for no reason at all. Many people with OCD have phobias, and these phobias may interfere with normal life, such as a fear of blood leading someone to never step foot in a doctor's office. Perfectionism and OCD are not the same thing, though perfectionism can be a quality in both.