Elna Koopman from Ukiah hasn't been seen since leaving her home Monday around 12 p.m.
Authorities say she has early stages of dementia and may be confused as to where she lives.
Koopman owns a Toyota Sienna minivan, with the California license plate number: 5HGN279.
She owns a home in Dallas, Texas and maybe be driving there.
If you see her, police are asking that you call them.