Christie Brinkley and Billy Joel have been the friendly exes and that is on display after his recently shared medical diagnosis.

Christie Brinkley is showing support for her ex-husband Billy Joel following news of his recent brain diagnosis. The supermodel, who shares daughter Alexa Ray with the legendary singer, posted a video on Instagram Saturday -- just one day after Joel revealed he had been diagnosed with normal pressure hydrocephalus.

Earlier this year iconic model Christie Brinkley debuted her new memoir, Uptown Girl, where she discussed her own life while detailing failed marriages with Peter Cook and musician Billy Joel - among other things.