I have two children who are on the autistic spectrum -- high-functioning. At one time, they would have been said to have "Asperger's Syndrome" but the latest edition of the specification manual (DSM-5) no longer uses that term. They are great people, and I am proud of them, and it is only when they are actively interacting with others that one notices that they don't interact quite the same as others. The chances are excellent that I am also "on the spectrum" though I am undiagnosed and have succeeded in training myself so that I only occasionally get into communications difficulties.
Some groups look at being on the autistic spectrum as a disease for which one can find a cure. For many other people, being on the autistic spectrum is not considered a "malady". It is a different configuration, and organization, of the brain and it has advantages as well as disadvantages. I have occasional thoughts as to whether this change of brain function might be part of a quantum "jump" in human behavior -- the next step in human evolution such as described by Greg Bear in his book Darwin's Radio. That would explain why the diagnosis is happening in greater numbers.
My sons are in good company with many others (for some historical figures, it is only a likely diagnosis based on behaviors) who are considered to have been on the autistic spectrum -- people like Dan Ackroyd, Charles Darwin, Emily Dickinson, Bill Gates, Steve Jobs, Barbara McClintock, Michelangelo, Andy Warhol, and Mozart -- just to name a few of many.
One may notice that these folks have a couple of things obviously in common. They are very creative and they are capable of great focus. (For some individuals, these aspects are so strong that it renders them almost incapable of interacting with others -- this is why it is considered to be a "spectrum" of behavior.) They also had great difficulties in interacting with others (which can be overcome with work -- replacing "instinctual", or "innate", responses with learned responses). And this difficulty interacting with others is the aspect that can be considered an "invisible malady".
Unlike a Down's Syndrome person or a mobility challenged person or someone who has some other externally observable difference -- you cannot tell a person is on the autistic spectrum by just looking at them (with the caveat that you might interpret based on behaviors). There have been times I have wondered -- would it be better to have an "A" on the forehead as an advance indication or not? Would that carry with it extra preconceptions prior to even directly interacting with the person or would it reset the expectations of the "neurotypical" (non autistic-spectrum person)? In either case, the effect would still depend on the adequate education of the "neurotypical" person (which often still needs considerable improvement).
I also have mild narcolepsy. My family has considered it quite hilarious to take photos of me nodding off at the circus, or the middle of a movie. I have also been known to fall asleep in the middle of a sentence while reading. It normally only lasts a few minutes. There are some medications that help with the condition but not everyone can deal with the side-effects. Midday naps can help as can regular nights of sleep. The primary time to be particularly careful is while driving. However, at work, this can also be an embarrassment to managers when they don't want to deal with medical conditions. Once again, it is an "invisible malady".
There are many other "invisible maladies". Some are recognized by, and accepted by, others because of their prevalence. Migraines are one such -- enough people have migraines -- or directly know someone with migraines -- that people say "oh, yes, I understand". There are others -- kidney stones, hemorrhoids, ingrown nails, and so forth -- that are also known, and accepted, because of prevalence.
It is those differences, and ailments, which are NOT prevalent that cause the greatest difficulty because it is harder for others to empathize and take behaviors into account. Many psychiatric conditions may fall into this category. Sometimes, the "malady" might be acceptable to others but it is too embarrassing for the person to tell others about it affecting them. In any case, the "invisible maladies" become acceptable by others only through experience and education.
