A children's author whose body was found in a cesspit "panicked" about forgetful incidents in the weeks before she vanished, her mother told a court.
Helen Bailey was found dead at her home in Royston, Hertfordshire, last July.
Her fiancé, Ian Stewart, 56, denies murdering the 51-year-old by plying her with sedatives in a financially-motivated plot.
Eileen Bailey told St Albans Crown Court her daughter had felt "highly anxious" and "spaced out" all the time.
Ms Bailey's body was found alongside that of her dachshund, Boris, under the garage at the home she shared with Mr Stewart three months after he had reported her missing.
In the weeks before she had vanished, Mrs Bailey said her daughter had confided in her about leaving Boris on the beach by mistake and not being able to recognise her hands on a computer keyboard.
"That really worried me. She just had such a good memory beforehand," Mrs Bailey told the jury.
A post-mortem examination found traces of an anti-insomnia drug which had been prescribed to Mr Stewart, the court heard previously.
Mrs Bailey described how her daughter had called her and told her "in this panicked voice" that she had "just slept five hours" after having a full night's sleep.
She told the court she thought Mr Stewart had cooked her daughter breakfast on the morning of the call, but on cross-examination said she could not be sure.
Mrs Bailey, 88, also said she had felt "uneasy" about the relationship between Ms Bailey and Mr Stewart.
"Latterly I was quite unhappy - mainly because of Helen's state of mind," she said.
Mr Stewart denies murder along with five other charges - preventing a lawful burial, fraud and three counts of perverting the course of justice.
The trial continues.