IDO has been targeted for neurological disorders: it causes decrease of serotonin level in the brain resulting depression, and it causes the accumulation of neurotoxic quinolinic acid.

• IDO与神经系统疾病也密切相关,它能降低5-羟色胺的水平而导致抑郁, 也可造成脑中喹啉酸等具有神经毒性的代谢产物的累积;