Loss of orexin neurons is primarily associated with which condition?

Loss of orexin neurons is primarily associated with narcolepsy because orexin, also known as hypocretin, is a neuropeptide that plays a crucial role in regulating wakefulness and maintaining sleep stability. In individuals with narcolepsy, particularly narcolepsy type 1, there is a significant reduction or complete absence of orexin-producing neurons in the hypothalamus. This loss leads to the characteristic symptoms of narcolepsy, including excessive daytime sleepiness and sudden episodes of sleep, as well as sleep disturbances like cataplexy.

The other conditions listed do not have this specific association with orexin neuron loss. While they may involve different aspects of sleep or attention regulation, they are not directly linked to the dysfunction of orexin pathways in the same way that narcolepsy is. The precise role of orexin in promoting alertness and regulating the sleep-wake cycle makes its loss a defining feature of narcolepsy.