Seven years later, his dad died.
That spurred Professor Brodaty, then a psychiatrist focused on depression, to dedicate his life to researching what at the time was a poorly understood condition.
Now 78, the pioneering brain researcher has been awarded Senior Australian of the Year for his work, which has touched countless lives.
In 1985, Prof Brodaty established one of the nation's first memory clinics, and went on to develop a dementia screening procedure which is now used around the world.
He also led a national training program for GPs, helping more than 5,000 doctors better understand the complex neurological condition, and has published more than 400 papers and book chapters.
Prof Brodaty founded the Centre for Healthy Brain Ageing in 2012, leading crucial research which improved the medical community's understanding of dementia risk and prevention techniques.
His three-year "maintain your brain" trial found changes to a person's diet and exercise routine could help delay the onset of dementia by about one year.
Australia Day Council boss Mark Fraser said Prof Brodaty's work would have long-lasting benefits.
"Henry has turned his personal experience into a lifelong commitment to improving outcomes for people living with dementia," he said in a statement.
"His research is expanding understanding of the condition and identifying ways to prevent and delay its onset. His work will benefit not just those affected today, but all of us in the future," Mr Fraser said.
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