Pauline Phillips began writing the column after her twin sister, Esther Lederer, started writing a similar one for the Chicago Sun-Times in 1955. Lederer, who wrote as Ann Landers, died in June.
Phillips' daughter, Jeanne Phillips, now writes the Dear Abby column.
In a statement released Tuesday by the column's distributor, Universal Press Syndicate, the family said the deterioration of Pauline Phillips' memory has been slow.
Kathie Kerr, a spokeswoman for Kansas City-based Universal Press Syndicate, said she didn't know when Phillips had been diagnosed with Alzheimer's.
"I do know that she's in good spirits and physically is in good shape," Kerr said.
The column's distributor released the statement following media inquiries about Phillips' health, Kerr said.
Phillips, 84, has not been involved in the day-to-day business of the column for a couple of years, Kerr said.
Phillips acknowledged in December 2000 that she had shared writing duties with her daughter since 1987. Last month, Jeanne Phillips began taking sole credit for the column, which appears in 1,300 newspapers nationwide.
By Amy Shafer