My autistic daughter is also intellectually disabled. She needs lots of special care, often on a difficult-to-predict basis. It was especially so in the first years following her official diagnosis. Not sure if it's a good thing to mention this, though: I'm afraid the employer could take this as evidence that there's a significant risk that I could some day descend into a poor productivity phase (or even another leave, at no notice). It may also be the case someone could take all this as a positive, by correlating it to a potential underlying disposition or motivation to hard work and responsability, but it seems better not to count on the possibility that this effect could override the first one.

An option would be to tell employers that I was on a leave to take care of a very sick family member (say suffering from the illness I suffered from) that since then has been definitely transferred to a special care facility, while trying to "fill" the gap with some skill-sharpening/expansion activities I did during the period. Classical example being online courses directly related to my main career path. Unfortunately it was not the case, as a I took online courses on online education, while planning to apply for typical engineering jobs. It's still something to show for that time off. I can try to make it applicable - e.g. I can relate it to being able to gain a skill to train others or take team leadership if necessary, or find ways to train people in other offices without having to travel.

Current employer is aware of my somewhat extraordinary circumstances involving both, being a father of a disabled child (my autistic daughter is also intellectually disabled and needs lots of special care, often on an unpredictable basis) and suffering from anxiety disorders myself. The employer was able to offer special working conditions regularly (e.g. working from home during a crisis).