Autism

Autism was a degenerative disorder, initally thought to be idiopathic, but whose mechanism was actually triggered by the [contagious virus] vaccine and which effects were reverse-engineered back into time by the WHO (TV: The Invisible Enemy). While thought to be cocntagious, this was actually because autists tended to congregate online in certain spaces and emulate each other's behaviour patterns. (PROSE: My Diary Desu) Being a spectrum, autists could blend in more or less well with their surroundings. On the lighter side of things, Binge and other tripfags were reasonable individuals who were only there to discuss the programme, while other more invested anons typically answered all manner of bait and Judy posts. At the bottom of the spectrum were the likes of Asher and Karenfag whose opinions were the most basic and NPCish possible and who couldn't stop themselves from injecting their personal problems into the thread, hence the use of trips to drive it home that they would never be real boys.

Judy's former son was affected by it.

In the show itself
It is commonly agreed that 12 and s8 onwards Clara were situated somewhere on the autism spectrum, as evidenced by the difficulty with which they conducted their interpersonal relationships and retreated further inside the TARDIS. Similarly, nearly every Classic charactere, main, recurring and guest alike seems to manifest some kind of autism, though this is certainly less than deliberate and about as valid as Twitter users diagnosing themselves. The fact is that the dialogue portrayed on screen was a product of its time and displayed the usual inhibition and staidness of the country historically, as well as Doctor Who being an adventure show with emphasis naturally on the plot, set and monsters rather than the actual lines and delivery. A good chunk of the latter can also be ascribed to shit writing, which might as well be considered a stylistic and integral trait of the show now. Thank god we have such realistic and lively dialogue in nuWho!