Interesting! I can't claim to identify with this from my childhood, though. Not that I didn't have a temper at times. I had rather clear periods of euphoria (and other typical manic type features) and depression (mostly anxious), but they started at around 14.

My youngest nephew was diagnosed with Asperger's Syndrome when he was quite young. That dx was pretty clear for him. Coincidentally, his older brother eventually also received an Asperger's diagnosis, but years later. My older nephew also received an ADD diagnosis, inattentive type. He has always been a quiet easy-going person, even in childhood. My younger nephew was usually quiet and often depressed, even at a very young age, like 6, but he would have violent outbursts at times a few years later (I think usually provoked to at least a small degree) and my sister said he'd have periods where he'd pace back and forth in distress. The worst of his childhood "mood" issues were suicidal depression related. As he got older (16/17) he would physically fight his father and the police were called (though I believe he was again provoked to various degrees). At about 19, he hit my older nephew to the degree where not only were cops called, but he had a restraining order put against him. He lived with my dad and brother, and while there he was very quiet and calm. He was only tentatively diagnosed bipolar at that time (along with Asperger's), taking bipolar meds, but later more firmly dxd bipolar.

My sister (their mother) also has a bipolar diagnosis, and it seems from her descriptions, and my childhood observations, that her elevated moods were exhibited mostly as violence, fury, and severe frustrated distress (mixed episodes), like my youngest nephew's. My bipolar manic episodes had some of that, but plenty of more classic euphoric manic features.

The point to my share here is that bipolar can look different in different people, but my curiosity about the Disruptive Mood Dysregulation Disorder is if it requires clear depressive symptoms. The articles referenced above don't clearly mention depression. If there is no clear depression, I'd wonder how certain a full fledged bipolar diagnosis will be.