Jim Crombie says people don't believe him when he tells them he's been diagnosed with dementia.

"I don't think they understand what dementia is," he said.

Dementia describes a collection of symptoms that are caused by disorders affecting the brain.

According to Dementia Australia, dementia might impact thinking, communication, memory and in some instances behaviour, and/or the ability to perform everyday tasks.

Mr Crombie said there's a misconception amongst the community that intelligent people won't be diagnosed with the disease.

Mr Crombie wants people to know dementia doesn't discriminate. People can be diagnosed regardless of their background, profession and age.

Mr Crombie received his diagnosis of younger onset dementia in late 2014.

"The family said I wasn't driving as well as I should," he said.

"They said I was different but I didn't feel any different."

While Jim's short term memory continues to decline, his long term memory is extraordinary.

Jim can remember memories of his childhood, from when he was aged three-years-old.

"I remember throwing a brick through a tiled roof," he said.

"I climbed a tree in my cousin's backyard and got up on the roof that way."

Since the diagnosis, Mr Crombie said his home has been "re-papered". There are notes stuck in each room to ensure he remembers certain things around the house.

Before the diagnosis Mr Crombie held active roles in the community, including as chaplain at Port Macquarie Local Court. In earlier days he worked as an electrical engineer and mechanical engineer.

Years ago Mr Crombie started up a group for men in Wauchope. It's a group which he continues to participate in and maintains a leadership role.

Mr Crombie also volunteers at The Salvation Army. He credits his Christianity faith as helping to keep going forward.

Mr Crombie's wife Susan is his primary carer and she said her whole life has changed since the diagnosis.

"I've become the chauffeur, banker and organiser," she said.

Mrs Crombie said the role of being a nurse and carer hasn't come naturally and she's learnt a lot along the way.

Read more: Jim and Susan Crombie praise Omnicare Alliance

She has undertaken training and meets a group of other carers each month for ongoing support.

"For a while I felt like I had to throw so much into the carer's role that it felt like we were losing Jim and Susan as a couple," she said.

However, Mrs Crombie said time has made it easier to accept their life as it is now.

Mr Crombie's personality has changed since he was diagnosed.

He finds it difficult to keep his emotions level and gets cranky more often.

"I don't know where it comes from but I've lost that control that I though I had before," he said.

Mr Crombie admits he gets frustrated he can't do things he did previously, like drive a car.

However he has learnt to enjoy other things in life.

Mr Crombie takes part in day centre programs through Hastings District Respite Care at Greenmeadows, as well as receiving tailor-made support from a support worker.

He enjoys reading poetry, researching local history, drawing, painting and chatting to the men at the centre.

Dementia is not a normal part of ageing and it can impact anyone at any age, although it is more common in people over the age of 65 years.

For more information, please visit dementia.org.au

If you are concerned about a loved one and their memory, please call the National Dementia Helpline 1800 100 500.

The National Dementia Helpline is open Monday to Friday from 9am to 5pm, except public holidays.