About 60 people - including police, firefighters and defence personnel - are continuing to search for an elderly Auckland woman with Alzheimer's who has been missing for six days.

North Shore police Inspector Sunny Patel said police held "grave concerns" for Pat Wearn, 73, who was last seen leaving her Caversham Dr, Torbay home at lunchtime on Monday to go for a walk.

Search and Rescue volunteers have travelled from as far as the Waikato, Thames and Pauanui to help authorities search nearby properties, dense bush and reserves for Wearn.

Civil Defence members and navy and airforce personnel have also been called in to assit firefighters and police with the search.

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Patel appealed to Torbay residents to recheck their properties for her.

"I know we keep saying this but it so important for anyone who hasn't checked their backyard each day, to please do so," Patel said.

"Pat may have sought shelter and if you checked your property on Tuesday, she could have tried to find someone to lie down on Wednesday morning and be laying somewhere that hasn't been checked in a few days."

He asked anyone who was unable to adequately check their own property to contact North Shore police on 09 477 5000 for assistance.