Final answer:
Enduring despair that remains unresolved over a long time is known as major depressive disorder, a condition where synaptic coupling impacts mood regulation and is linked to the hopelessness theory.
Step-by-step explanation:
Enduring despair that remains unresolved over an extended period of time is called major depressive disorder. This mental illness is characterized by prolonged periods of sadness, where synaptic coupling between a pre-and postsynaptic cell plays a role in the neurobiological aspects of the disorder. The learned helplessness model, including its updated form known as the hopelessness theory, explains how individuals may come to see themselves as unable to change or improve their situations, leading to symptoms of depression.
It's important to differentiate major depression from personality disorders, which are enduring patterns of behavior that lead to distress or impairment but aren't typically characterized by protracted periods of sadness. Major depressive disorder is one of the most common mental disorders in the United States and requires proper diagnosis and treatment to manage. While disorders like PTSD also result from severe psychological trauma and involve prolonged distress, the specifics of the disorder, such as its association with anxiety and its historical context, differ significantly from that of major depression.