PDE4A and early-onset autosomal dominant Alzheimer disease: Indeed, selective PDE4 inhibitors have generated substantial interest as a treatment for several autoimmune conditions including ankylosing spondylitis, Alzheimer’s disease, psoriasis, psoriatic arthritis, sarcoidosis, systemic lupus erythematosus, inflammatory bowel disease, atopic dermatitis, rheumatoid arthritis, and multiple sclerosis.