Interleukin-9 (IL-9) secreting Th9 cells were upregulated in both CAH [median 2.1% (range 0.9 – 3.8%), p < 0.0001] and BADx patients [median 3.3% (range 1.2 – 6.5%), p < 0.0001] compared to controls [median 0.2% (range 0.2 – 0.6%)] with no major difference in AD patients [median 0.5% (range 0.2 – 0.7%), p > 0.9999]. This evidence concerns the gene IL9 and Alzheimer disease.