Aaron's persistent feelings of sadness and impending doom dominate his life. every time he says anything even a little positive to his therapist, the therapist smiles. otherwise the therapist has a stone face. this therapist is probably using some variation of:

explanation:

allergens: overstimulate the nerve system

neurotics: attack nerve cells

mutagens: damage or otherwise alter dna sequence

generators: cause defects during growth and development  

carcinogens: cause unchecked cell growth

i hope you get the idea according to me these are the effects that happened.