Did a quick google search and it seems like autism and aphantasia are linked by impaired imagination and social skills. There's a higher rate of aphantasia among autistic individuals than the general population, and vice versa--those with aphantasia have a higher rate of autistic traits than the general population. Personally I have some degree of aphantasia, and I do feel its related to being autistic.

Oh, that's a new term for me but it fits. I can think of a river and might recall flashes of rivers I've seen in my past but I can't hold an image in my mind that I can see. I just think of the word river over and over again.