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People with dementia experience changes that can impact how they live everyday life. But one of the most damaging and threatening experiences they face is the potential to wander and become lost.
Fear that a person with dementia will leave a safe environment alone and become lost has led to some carers resorting to extreme measures to ensure the person's safety, such as 24 hour supervision, or the use of physical and chemical restraints.
Many of these measures are either not sustainable, or removes the person's autonomy and lowers their quality of life.
Dementia is a term used to describe symptoms associated with progressive and incurable decline in brain function. Dementia can be caused by over 100 diseases with Alzheimer's disease being the most common cause.
"Dementia can cause damage to the parts of the brain needed for successful navigation. This puts people with dementia at more risk of becoming lost," MacAndrew explains in an interview with ScienceAlert.
"Internationally, it is estimated that 30-60 percent of people with dementia will experience at least one getting lost event."
Wandering and then getting lost can lead to life-threatening situations, such as exhaustion, falls, malnutrition, and in the worst cases, deaths.
MacAndrew explained to ScienceAlert that this tendency to wander can be triggered by a number of factors including the "cause of dementia and the area of the brain damaged by disease, past habits and interests, and immediate unmet needs such as pain, boredom and hunger".
To get an idea of how many people with dementia go missing, MacAndrew and her colleagues searched the media for all reported missing people with dementia in Australia between 2011 and 2015.
Of the 130 cases they found, only 71 percent of the missing people were located alive. Of those found alive 20 percent were found injured.
These statistics are likely less than the true figures, explain the researchers, as not all cases of missing people are reported in the news.
"Most people with dementia who become lost and are found, are found less than 5 kilometres from their last known location," says MacAndrew.
"Those found 1-2 hours after being noticed as missing have a greater chance of being found alive; delays in starting a search decrease the potential to find them."
Misconceptions about having to wait 24 hours before reporting someone missing have led to search delays in the past, according to the Search and Rescue unit in Brisbane.
"This is not the case - particularly for vulnerable people like people with dementia," MacAndrew explains.
The researchers have recommended Australia adopts a standardised system of reporting a missing person with dementia and perhaps an alert system such as the 'Silver Alert' system, similar to the Amber Alerts we have for missing children.
This type of system has already been implemented in the US, where they have similar rates of people with dementia going missing.
Becoming lost can be especially problematic during natural disasters and those with dementia are also at greater risk during these events.
"Research studies reveal exposure to a natural disaster may exacerbate dementia symptoms and increase the risk of functional decline, hospitalisation and mortality," says nurse researcher Dr Linda Schnitker who was also part of the study.
Increased deaths of residents with dementia have been reported after disasters such as 2008's Hurricane Gustave in the US. Tropical cyclone Yasi in Australia also highlighted the additional risks.
The guide includes advice on how to judge what type of response is required for different emergencies, how to plan for evacuations and how to prepare an emergency kit.
It also recommends carers to sign up to programs such as MediAlert that provide identity bracelets so if someone does go missing they can easily be identified.
"For carers of people with dementia, there is an extra layer of anxiety and potential danger during disasters. They need to consider how to best help the person they care for and also protect themselves from harm," says Schnitker.
"A current photo, an identify bracelet and access to health records can save lives."