10/07/2017 10:29 PM AEST | Updated 10/07/2017 10:29 PM AEST

The Heartbreaking Human Cost Of Dementia In Australia

More than 400,000 Australians currently live with the disease.

Dementia is the second leading cause of death in Australia and with more than 400,000 people living with the disease -- and the possibility of that number rising to more than half a million by 2025 -- the national issue is becoming epidemic.

In an investigation by the ABC's 'Four Corners' program on Monday night, the heartbreaking realities of the mental disorder were brought to light as individuals battle with the loss of identity and confusion that comes with conditions such as Alzheimer's Disease.

Dementia, and its various forms and causes, refers to symptoms affecting the brain that can often result in interferences to a person's thinking, behaviour and typical social activity.

For 79-year-old Brian Fischer, the hardest thing to come to terms with when it comes to living with Alzheimer's Disease is "the realisation that you can't do as much as you used to be able to do."

"I can't put a date on it when it really became difficult. I was losing the zest, the zoom, the desire to go and achieve things that I knew I could achieve," he told 'Four Corners'.

"Then you stop three or four things, then you think, 'what am I doing? I don't do anything anymore,'".

For Brian's wife, Heather, that personal loss of identity as a result of the disorder came to a head when he began acting out as a way to vent his frustrations.

"We had three awful years of tension and friction and a feeling of absolute hopelessness," she said.

"Twelve months ago, Brian was getting so frustrated that he started becoming a little physically aggressive, which was just not him. And he would be angry and throw things.

"On one occasion he actually hit me across the face, which was just devastating for him because he's a kind, gentle man who would not approve of that in anybody whatsoever."

And for Brian, the damage done to his self-esteem was immediate. "I'm embarrassed to talk about it. I'm ashamed to talk about it," he said.

"Yes, I have hit Heather. She tried to help me with something once and put her hand up towards my face, and I said, 'don't do that.' I don't know why. It's not me.

"Here was I, hitting the person I loved, hitting my best friend. She puts herself out so much to help me and I'm starting to get physically violent."

For Mandy Lovell, the wife of younger onset dementia sufferer Garry, the slow degradation of a loved one is a sad reality of Dementia.

"It's really difficult to lose little pieces of the person that you love. Sometimes that happens quite quickly. And other times, you kind of don't realise that it's happened until a little bit later," she said.

"And I think the hardest thing to witness is watching someone that you love suffer."

There are more than 25,000 people living with diagnosed younger offset dementia, which is expected to rise to more than 42,000 by 2056 and can affect anyone under the age of 65 -- with some in their 30s included in those suffering from the condition.

And while this paints a bleak picture for individuals living with the disease, Garry told 'Four Corners' he finds more hope in living positively with belief in the researchers "doing a lot of work trying to find something" to aid sufferers.

"I'm hoping they'll find some kind of drug that might slow it down or even stop it. So I'm kind of positive to think like that, which doesn't make you feel doom and gloom all the time," he said.

"That's always a good thing to think about if you're feeling a bit gloomy, just there's a lot of people doing a lot of work trying to find something, even if it just slows it down. I mean, that could happen any time."

While there are some medications currently being tested by scientists working at limiting reduced brain function, calls within Australia for a national strategy to deal with Dementia were ramped up in 2016 in order to curb the potential health and economic crisis.

According to Dr Ronald Petersen, Ronald Reagan's former physician and currently Director of the U.S. Mayo Clinic Alzheimer's Disease Research Centre, a national approach could have the same success as fights against other diseases, such as influenza and pneumonia.

"The increasing ageing of so many countries and societies, with age being the biggest risk factor for the disease, it is absolutely fundamental that we attack this now because if we wait five to 10 years we're going to get even farther behind the eight-ball," he told HuffPost Australia.

You can watch the full 'Forget me not' episode aired by 'Four Corners' on Monday on ABC iView.