Shell-shocked soldiers were often considered cowards or malingerers. One doctor said that shell-shock was a "manifestation of childishness and femininity". Treatment included electro-shock therapy, hot and cold baths, massage, daily marches, athletic activities, and sometimes hypnosis. Officers were sometimes given psychoanalysis as well, especially at the famous Craiglockhart War Hospital in Scotland, which treated poets Siegfried Sassoon and Wilfred Owen.
Medical evidence showed that shell concussion could cause neurological damage - tiny hemorrhages in the brain and central nervous system. But men exhibited symptoms of shell-shock even when they had not been exposed to shell fire. In 1916, a distinction was made between those who were shell-shock wounded (W) and sick (S). Wounded was honourable.
Here is a clip that shows soldiers who were severely shell-shocked.