Final answer:
Anorexia nervosa is the mental disorder with the highest mortality rate due to severe malnutrition and other medical complications.
Step-by-step explanation:
The mental disorder that carries the highest mortality rate is anorexia nervosa. Anorexia nervosa is an eating disorder characterized by an intense fear of gaining weight, a distorted body image, and extreme restriction of food intake. This disorder can lead to severe malnutrition and other medical complications, which can ultimately result in death.