TH and Alzheimer disease: The estimated number of TH-ir LC neurons in the NCI group was 19,495 ± 2,891(mean ± SD; range = 25,867–14,758), whereas neuron number was progressively decreased in the aMCI (14,283 ± 2,757; range = 19,874–10,645) and AD ( 10,628 ± 2,946; range = 15,834–6,453) groups.