An auntie is running to raise money and awareness of a poorly understood type of autism, which can be mistaken for ‘naughtiness’.

Fiona Brinkworth, from Fleetville, St Albans, is training for the Milton Keynes Marathon in aid of the charity which supports her eight-year-old niece.

The 26-year-old will run the 26 miles for the PDA Society, which she says is fundamental to helping families experiencing Pathological Demand Avoidance Syndrome.

Her niece, who also lives in St Albans, was diagnosed with autism aged three. Usual parenting strategies did not work with her but nor did approaches designed for typical autism.

Fiona said: “They somehow instinctively found their own way of approaching things with her but to be honest were baffled. It was only when someone in a SEND (special educational needs and disability) support group suggested looking into PDA, that everything finally started to make sense. It is not well known even amongst professionals and not something we had ever heard of.

“The PDA Society has been a brilliant source of information and support for our family. The conference her dad attended really helped and it was great for him to listen to speakers and meet other parents – a useful reminder we are not alone.”

Squiggle’s mum Katie Brinkworth, 37, is a lifestyle blogger and writes about home education among other topics. They use Squiggle as a nickname to protect her anonymity.

The features of PDA include obsessive resistance of ordinary demands, appearing sociable but lacking depth in understanding, severe and sudden mood swings, language delay and obsessive behaviour focused on people rather than things. Sufferers are often comfortable to an extreme extent when engaging in role-play and pretending.

According to the PDA Society website: “PDA is increasingly recognized as part of the autism spectrum. The central difficulty for people with PDA is their avoidance of the everyday demands made by other people, due to their high anxiety levels when they feel they are not in control.”

Because of this many children with PDA avoid doing as they are told to a far greater extent than is considered usual – but because it is still poorly understood generally, the symptoms of PDA are often mistaken, especially by strangers or teachers, for ‘bad behaviour’.

Katie explained: “Children, like anyone else, need to feel understood, supported and valued. This is why it is so crucial for parents to understand their children. It makes a massive difference to how they connect with them. It also enables parents to develop approaches that work for the individual, therefore creating a calmer happier environment.

“Understanding autism fosters greater empathy towards that person, which positively affects the relationship. Ignorance and lack of understanding can create fear and hate. I have seen some nasty online attacks about PDA because people don’t actually understand it.

“When people are more familiar with something, it becomes more comfortable and accepted – even celebrated. This is why raising awareness is an important part of the process. It is much easier all round when you feel you can expect understanding and empathy rather than judgement and discrimination.”

Her sister-in-law Fiona, who is aiming to raise £1,000 for PDA Society through the event in May, added: “This will be the hardest challenge I’ve taken on ever, so please dig deep and make all these blisters worth it!”

To donate, go to www.justgiving.com/fundraising/fiona-brinkworth.