Answer:
vicious cycle
Explanation:
According to my research on depressive disorder, I can say that based on the information provided within the question Neal's depression is most likely due to a vicious cycle in Neal's actions. Neal is dealing with negative stress which turns him pessimistic, his pessimism causes him to become depressed, and finally his depression causes him more stress which once again causes him to be pessimistic and so on. This is a never-ending circle of depression.
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