With a quarter of acute hospital beds occupied by people with dementia, she said it is vital that hospital design promotes patient safety rather than put people at risk.
The former BBC News presenter was speaking at the launch of the world's first dementia-friendly Virtual Hospital at the Design Council in central London.
Faster growing group of hospital admissions
"Patients living with dementia are the fastest growing group of new admissions in our hospitals, but even some of the most modern are wholly unsuitable environments for people affected by this condition," she said.
"This new virtual resource demonstrates how acute design can be practically applied to meet the needs of this group of patients more effectively."
The Virtual Hospital has been developed by the Dementia Services Development Centre (DSDC), which is part of the University of Stirling.
"We know that traditional acute hospitals are very dangerous places for people with dementia," added DSDC director, Professor June Andrews.
"But we also know from the evidence how to make them safer environments, and we have developed this resource to share our knowledge widely.
"As our populations age, dementia rates are set to soar around the world. Many older people experiencing cognitive decline will still need to access acute care, and they deserve to have their needs met safely."