There is no publicly known official diagnosis of autism or Asperger's Syndrome for Michael Jackson. People will speculate about various possible conditions he might have that explain his actions. However, only a professional can make that diagnosis with any accuracy, and no such professional is currently known to have made such a diagnosis as yet.
For a diagnosis of autism, he should have had delayed language and cognitive development. With either average or above average intelligence, if he has one of these conditions, it is more likely that he would be diagnosed with Asperger's Syndrome.
Michael Jackson certainly shows signs of Asperger's Syndrome (AS). His unusual behaviour has often been blamed on his upbringing: however his siblings are relatively normal, with a similar upbringing, so I do not feel this is the cause.
Michael is often seen as shy, and has difficulty relating to many people. His friends are a few people with whom he has common interests, especially the background of being a child star. He mostly seems to be able to relate to children, however, perhaps reflecting the social immaturity which may be seen in Asperger's. Regardless of maturity level, people with Asperger's seem to be more comfortable with those older or younger than their peer group.
He performed the song "Ben" at a young age (in 1972), about his pet rat being his only friend. This song was written by Don Black and Walter Scharf for the film Ben. It is possible that he was able to relate to the lyrics, but there is not evidence that it was significant for him as anything other than a successful single. Another of his key relationships was with his chimp, Bubbles: it is common for those with AS to relate better to animals than people.
I wonder if the lines at the start of "Thriller": where Michael is with a girlfriend, then says "I'm not like other guys" and turns into a werewolf, reflect his feeling that he is different from other people.
Like many with AS, Michael has some unusual ideas and interests, not seeming to realise the impact these have on what others think of him as a public figure, and contributing to his loss of popularity. One example would be his paranoia about germs.
Like many with AS, Michael is very talented in one area: music, but has a lack of common sense in many other areas, such as money management and social behaviour. He also tends to perseverate in his activities. In the late 1990s and early 2000s, when he began to lose popularity, instead of changing his image and music, or taking up another activity, he persisted with similar music and dance moves despite evidence that this not longer worked. Contrast this with, for example, Madonna, who does not have AS, and her keen sense of the need to change with the times.
The following information was provided to me because I am not very familiar with Michael Jackson's behaviors. No single behavior proves that Michael Jackson does not have autism or Asperger's Syndrome, just as no single behavior proves that he does.
Eccentric interests are one reason given for considering the possibility that he has AS. However, his wearing of a surgical mask has been variously attributed to a desire for privacy, to vitiligo, or to a fear of germs. A number of people without autism or AS have a fear of germs, although it is also seen in some people with autism and AS. There were rumors about him sleeping in an oxygen chamber, but he claimed that he purchased it to donate to the Brotman Medical Center. As a public figure, any activity of his could be exaggerated, since it helps to sell newspapers. Thus, it can be more difficult to evaluate behaviors as signs of AS if one does not know the person in his or her private life.
At concerts, Michael Jackson is surrounded by people who crowd around him, and this does not seem to disturb him the way it would disturb a person with autism or Asperger's Syndrome. He also does not seem to have difficulty interacting with them.
Most people with autism and Asperger's Syndrome are stressed by change. They might feel more comfortable wearing the same clothes, having the same blankets and pillows on their beds, keeping the furniture in the same locations in rooms, using the same glasses and dinnerware, eating the same food at the same time every day, etc. Being on tour likely would be very stressful, although people with Asperger's Syndrome can learn to accommodate it. They are not reports of Michael having this sort of stress during his first years of touring when difficulties would probably be most pronounced.
In addition, people with autism and Asperger's Syndrome are often described as lacking a sense of humor. Although this is not necessarily true, their senses of humor are more likely not to be understood by others. In general, they interpret words literally and use them literally, which interferes with understanding and expressing certain types of humor. Michael Jackson is purported to be hilarious, often using sarcasm. This could also indicate that he does not have autism or Asperger's Syndrome.
It might be added that people with AS often have retarded hand-eye-coordination, which would seriously compromise the ability to dance. Persons with AS can be very athletic, but rather in sports like running (as my brother, who has AS) or swimming, not involving complicated movements. As arguably one of the best pop dancers in the world, Michael Jackson is unlikely to have had Asperger's Syndrome.
I also asked the opinion of some other people familiar with autism and Asperger's Syndrome, as well as Michael Jackson's behaviors, and they doubt that he has either condition, although I was not given a list of contraindicators by them. However, it was pointed out that although he had the same general upbringing as his siblings, he was a child star at a younger age, so there was a difference in environmental factors that could explain the differences between his siblings and him.
Does Michael Jackson instead have Exposure Anxiety, a condition that might be confused with autism? As a performer he was fearless, wildly creative, innovative, in his own world and a league of his own. As a person, he was somewhere between painfully shy and extremely vigilant. In his interviews he'd fluctuate between almost autistic in his avoidance of direct touch, eye contact and his voice could retreat to a timid whisper. Then, in the blink of an eye, he could confront before, just as quick, he'd be gone again. His gaze, when not performing, was fleeting, his body speaking the typical fight-flight postures of Exposure Anxiety. And like those with Exposure Anxiety who find freedom in doing not 'as oneself', 'by oneself' or 'for oneself', he could reach amazing heights of expression when in the role of performer or philanthropist.
Akin to those with Exposure Anxiety, he found it easier to be around animals and in relative solitude and was fascinated with a man who spent most of his life hiding; The Elephant Man. Michael Jackson could sing with the passion of the gods, but in public conversation seemed afraid of the sound of his own voice. He could perform and pose with the confidence of a super model, but spent large parts of his adulthood, removing himself from the exposure of his own face. He spent his life connecting with other people but put a glove between them and the exposed contact of a handshake.
Watching him some years ago when I first wrote of Exposure Anxiety, I felt an urge to write to him about Exposure Anxiety, but didn't. Ironically, I felt it was too exposing to do something so personal, especially in the direction of someone already so public, so exposed. Two weeks before his death I sent out an article on Exposure Anxiety calling for public views on which famous people might have this. Several suggested Michael Jackson and so, agreeing with this, I listed him on my blog in an article on Exposure Anxiety in which I listed famous people who may have had Exposure Anxiety.