@darkstarofchaos makes some super interesting, well backed-up points. However, to extend the discussion and, perhaps to play devil’s advocate, I would like to offer another perspective on this fascinating topic on my favourite character.
(Disclaimer: People are free to decide for themselves whether they want to interpret Starscream’s behaviour as ADHD/autistic or not. I’m just offering some arguments explaining my own reasoning for NOT interpreting Starscream’s behaviour in this way, which some people might agree with, and others might not.)
Firstly, I think it’s important to mention a key issue with discussing mental health conditions diagnoses in this way, and that is the blur between what is a medical diagnosis of mental health issues, and personality.
There are 2 significant implications involved with using mental health conditions in interpreting certain behaviours:
1) The person’s behaviours/mental states/thought processes have become, or are, to some degree, involuntary, or something they cannot control or cope with in a healthy manner.
2) The person suffers in some way because they cannot voluntarily control their behaviours/mental states, whether they are affected by the mental states directly (e.g. anxiety, depression), or they suffer social/physical consequences due to their mental states (e.g. lack of motivation to feed yourself properly; social stigma and ostracisation from social groups because of behaviour)
Obviously, Starscream suffers from Megatron’s abuse, and sometimes the abuse of other Decepticons, for some of the things he says or does. The extent to which this affects his ‘everyday functioning’ I think is pretty debatable, so I’ll leave that open to people’s imaginations.
If we consider only criteria 1 for now though, then I would argue that Starscream’s behaviours are intentional (e.g. openly criticising Megatron’s plans, loudly and aggressively talking to other people etc.). He is blatant and scathing towards Megatron because he actively hates him, and intentionally wants to make sure Megatron knows it - not because he doesn’t understand that he shouldn’t speak to his superior in this way, or that the way he speaks is aggravating to others. He speaks that way because he actively wants to hurt/threaten/insult/humiliate others, be it Megatron, his superior, or any other underling of his (e.g. Rumble, Skyfire, Skywarp and Thundercracker etc.)
I would also argue that his military ranking provides quite a strong, alternative explanation for his less empathetic behaviours. Because Starscream is a very important figure of authority in a strictly hierarchical environment, basically every other character he interacts with (outside of Megatron) is his underling, or an enemy. He knows his position, and his importance, outweighs those of the other Decepticons - so he simply doesn’t care about how they feel, or think, as long as they do what he tells them. While I certainly think he lacks empathy, I believe there’s also an element of active disinterest in anything other than himself, or anything that does not further his own cause.
I also think this attitude extended itself naturally to Skyfire, because at that point he had had millions of years’ experience in being a military commander and the habit was likely hard to break (that’s assuming he was different pre-war). He’s not entirely, involuntarily unaware of others’ discomforts and unhappiness around him. He just… actively doesn’t care.
As for recognising the Stunticons as Autobots in disguise, as well as identifying Galvatron to be Megatron without any notable evidence to suggest otherwise, maybe this could also be interpreted as evidence of Starscream’s sensitivity to other’s behaviour. Because there is no indication, appearance wise, to lead him to the assumptions that he did, then he could only have reached the conclusions he did through observation of their behaviours, be it the way they spoke, behaved, or moved. An autist should otherwise be less susceptible to picking up these subtle cues and differences in behaviour, particularly if we assume the others around Starscream to be non-ASD, in which case, they should theoretically be ‘better’, and quicker, at picking up these differences before Starscream noticed.
It could also be because Starscream is an inherently suspicious and paranoid character, which leads him to making wild assumptions and leaps of logic (even if they actually turn out to be correct, because plot.)
(That, or the writers just couldn’t be bothered to give anyone else screen-time. #justiceforreflector.)
On a more technical squabble, I think it’s important to point out that the main characteristics of ASD/ADD which were addressed above only cover a very small selection of the actual criteria for both in the DSM-V or ICD-10/11. Although some symptoms/behaviours may be commonly associated with a particular condition, unless otherwise specified however (e.g. schizophrenia), displaying only 2 or 3 behaviours is usually not enough to warrant an official diagnosis. (For example, there is ample evidence highlighting Starscream’s impulsivity. Hyperactivity… It’s hard to tell, granted, with the animation. And as for attention deficit, well… he doesn’t appear particularly inattentive, easily distracted, or careless/forgetful/disorganised). I do think some of the points (e.g. him reacting badly to being insulted, his interests in science, him being a soldier etc.) aren’t really that specific to ASD, but then again, G1 was pretty badly made, so there’s lots of room to fill in the blanks with your imagination.
That said, although I study psychology, I don’t have autism (to my knowledge), or close friends who have been professional diagnosed (to my knowledge), so there is a lot I don’t know. Also, ASD is a very complex condition that is different for everyone, so it’s plausible to imagine Starscream’s behaviours as how ASD has exhibited itself in him.
To summarise, G1 was pretty shoddy, so there’s plenty of room to imagine Starscream as ASD, but also plenty of room to imagine him as a natural twat. His psychology is still fascinating to examine though, and I, too, have too much time on my hands.