Autism

Sarah Jane Smith's granddaughter Lily was autistic. This manifested in many ways, including her tendency to scream when prevented from doing something she loved, such as playing in the snow, or her habit of attacking other children or simply hitting them. (PROSE: Lily) Professor Maeve Ruthven likened a fearful cry during her abduction to an autistic gurgling sound. (PROSE: Dry Pilgrimage)

Ryan Scott, who was also autistic, would sing to isolate himself from the world. (PROSE: Into the Silence)

Olivia Jennings thought that the Sixth Doctor might be autistic. (AUDIO: The Curious Incident of the Doctor in the Night-Time)

The Eighth Doctor spoke positively on many autistic children's "phenomenal" abilities to recall shapes and numbers. (PROSE: Fear Itself) Likewise, a young Bernice Summerfield likened her friend Eutemio's great enthusiasm for plane technology to "high-functioning autism on amphetamines." She suspected that his possible autism made him a good archaeologist for her team. (PROSE: Bernice Summerfield and the Library of Books)

Behind the scenes

Bethany Black, who appeared in Sleep No More, confirmed that she was autistic. (REF: THWR 250, THWR 251)

Chris Chibnall wrote the Thirteenth Doctor with the intent that they would share many of the same traits as those who were on the autism spectrum.