Psoriatic arthritis is a type of arthritis ONLY seen in people with the skin condition, psoriasis-- an autoimmune skin disorder that causes a scaly, red and itchy rash. PSORIATIC arthritis is caused by an overactive immune system that attacks the joints, causing inflammation, cartilage deterioration, and joint damage. About 15 percent of people with PSORIASIS will develop psoriatic arthritis. But doctors are still scratching their heads as to the CAUSE of PSORIATIC ARTHRITIS. Many people have a family history of the disease. But there is also a theory that psoriatic arthritis may be triggered in people with psoriasis by an infection that kicks their immune system into hyperdrive. Men and women develop PSORIATIC ARTHRITIS at similar rates. It commonly occurs in people ages 30 to 50. SYMPTOMS, such as painful, swollen joints, stiffness, fatigue and intermittent flares of pain, echo those of RHEUMATOID arthritis. HOWEVER, a FEW symptoms are unique to people with PSORIATIC arthritis. For example, they may experience DACTYLITIS, a swelling along ENTIRE fingers and toes. NAILS may become unhealthy-looking-sometimes they lift from the nail bed completely. Sometimes people with psoriatic arthritis get redness and pain in the tissues around the eyes. And there is often pain in a joint in the lower back. To relieve these symptoms, doctors prescribe the same medications used to treat RHEUMATOID arthritis. For more detailed information on arthritis, watch additional videos in this series.