It seems that "it" here refers to "it is hard for patients with this (depression) symptom to imagine the optimistic results of an action." But it is not the equivalent of "it."
Context:
Clinicians refer to this slowing down of motivation in depressed patients as "psychomotor retardation." According to Deisseroth, who is also a practicing psychiatrist, patients may experience this symptom mentally, finding it hard to envision the positive results of an action, or, he said, they may feel physically heavy, like their limbs just do not want to move. "This is one of the most debilitating aspects of depression, and motivation to take action is something that we can model in animals. That's the exciting opportunity for us as researchers," said Deisseroth, who also holds the D.H. Chen Professorship.
Top answer
It has no antecedent; it is merely a dummy.
— RandomGuy
It has no antecedent; it is merely a dummy.
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