The invention relates to compounds that demonstrate efficacy in blocking PACAP receptors (e.g. PAC1) and associated methods of treating neurological diseases or disorders using the disclosed compounds. The neurological diseases or disorders include, but are not limited to, stress-related diseases (e.g. chronic stress, post-traumatic stress disorder (PTSD), anxiety, or general anxiety disorder), pain-related diseases (e.g. chronic pain, primary headache disorders, or migraines), or addiction (e.g. addiction to a substance (e.g. addiction to cocaine, amphetamines, methamphetamine, methylphenidate, nicotine, alcohol, prescription medication, marijuana, tobacco, or an opioid selected from heroin, fentanyl, codeine, hydrocodone, morphine, oxycodone, hydromorphone, and methadone)).