Something else to note.

Acetylcholine is a vital neurotransmitter that is synthesized in the body. Patients with Alzheimers typically have a lower level of Acetylcholine and part of the treatment is to increase it with medication. This often leads to a "higher than normal" level of acetylcholine in the body, which is a direct link to depression.

This could be further exacerbated by the existing depression caused by basic PTSD symptoms. I wish the best for you both. Good luck.