PCSK9 and Alzheimer disease: However, by analyzing the two pathways contributing to total HDL-CEC, we found a significant increase of AD HDL-CEC (+7.8%; p = 0.0008; Figure 1B); however, PCSK9-i treatment promoted a trend towards a reduction of ABCA1 mediated HDL-CEC, without reaching statistical significance (p = 0.0513) (Figure 1C).