Marissa has been diagnosed with major depressive disorder. the amounts of serotonin and norepinephrine in her brain are likely to be depleted when she is depressed.
Step-by-step explanation:
Depression is a mood disorder. A person with a depressive disorder finds themselves in a constant negative mood state. People diagnosed with depressive disorder have various symptoms it includes low self-esteem, feeling inferior, inadequate, incompetent etc.
The daily routine becomes cumbersome like eating, taking a bath, putting on clothes. There are somatic symptoms like loss of appetite and weight loss, sleep disturbances.
Neurotransmitters like serotonin, norepinephrine and dopamine play a crucial role in brain chemistry because they regulate the feel good hormones and the pleasure/reward compartments of the brain.
A person with depression has depleted serotonin and norepinephrine, which is why medications that mimic the structure of these neurotransmitters when taken alleviate some percentage of the depressive disorder.