"I've been attending board meetings and I've had a voice, and we're hoping to do talks at schools to let other teenagers know that it's okay to ask for help."
September is Alzheimer's Awareness Month, and Fergusson-Ross said it wasn't just older people whose lives were changed by the onset of the disease.
"I will be able to share my own experiences, and I think some people do forget about the teenagers and how it can affect them.
"I guess one of the most important things I would say is to not be too afraid of it, and don't let it take up everything."
Fergusson-Ross said even after her grandfather was diagnosed, he still had a twinkle in his eye and he would light up when people came to visit.
"Make as much time for them as possible, and be there for them.
"Alzheimer's affects everyone differently, and you can be aggressive but you can also be quiet, but loved ones shouldn't take it to heart."
Alzheimer's Whanganui manager Wendy Paterson said, as far she knew, Fergusson-Ross was the first youth ambassador for Alzheimer's in New Zealand.
"She came along to our AGM and sits in at our meetings, and she's really, really good," Paterson said.
"We don't have any preconceived or pre-written ideas for her, because she is coming purely from her point of view.
"Tayla knows what dementia is and she's been through it with her grandad, so hopefully she'll be able to make young people understand what it is they're dealing with, so we can get that stigma away."
Paterson said the Alzheimer's Whanganui Fashion Parade fundraiser, scheduled for September 9, had been postponed due to Covid-19, but the annual Memory Walk would still take place on September 26.
"We have the Move for Dementia campaign running this month as well, which is up on our website.
"There are different challenges like aerobics, dancing or something out in nature, and you can share it with your family and friends.
"The whole thing was inspired by Captain Tom Moore in England, and the walks he did for charity."
For more information on Alzheimer's Awareness Month, go to www.alzheimers.org.nz/get-involved/world-alzheimers-month