Jay Leno’s wife, Mavis, is experiencing a decline in health due to advanced dementia, with new court documents revealing she sometimes does not recognize her husband or remember her own date of birth. The 77-year-old’s condition was detailed in a recent report filed by her court-appointed counsel, Ronald Ostrin, as part of a conservatorship petition initiated by Jay Leno in January. Leno sought conservatorship to establish a living trust for Mavis, looking to secure her future care through managed assets, especially in the event of his passing. The former “Tonight Show” host disclosed his wife’s diagnosis in the conservatorship documents,…