Henry Darger and autism
It seems to me that all the most common indicators of autism were present in the case of Henry Darger. Most notably, there was his penchant for keeping track of numbers, whether it be in his stories (war statistics) or in real life (keeping track of the weather ritualistically). Autism is typically characterized by repetitive or restricted behavior, which Henry Darger most certainly exhibited. As the film shows, his habits were repetitive and ritualistic. The film also demonstrates how highly restricted Henry's interests were.
Even his friendships were indicative of autism. From Wikipedia: "Contrary to common belief, autistic children do not prefer to be alone. Making and maintaining friendships often proves to be difficult for those with autism. For them, the quality of friendships, not the number of friends, predicts how lonely they feel." The film shows how important his Henry's few friendships were, as well as how lonely he felt when those friends were lost.
Henry's behavior was also indicative of autism. His resistance to change, his compulsive behavior, his talking to himself, and even his eating and sleeping habits demonstrated it.
To be honest, as I watched Henry's story unfold, I couldn't help but be reminded of controversial Internet personality Chris Chan, who has been diagnosed as with high-functioning autism. Chris has a series of drawings and stories remarkably similar to that of Henry's. Their manner of speech is nearly identical, as is their writing style. Both use long-winded narratives and describe even the minute aspects of their stories in great detail.
In the documentary, the possibility of Henry Darger's mental illness is touched on briefly. It's suggested that Henry may be schizophrenic, but this notion is quickly dismissed in the film. It disappoints me that the autism angle, which would explain much of Henry's behavior, is never explored.