Lorraine McMullen feared she was about to develop dementia after reading it was common in people at that age who suffered from a thyroid problem.
The mother-of-two, who was said by work colleagues to be a happy and fun member of staff at Fulwood and Cadley Primary School, kept her anxiety and depression secret from those outside her family.
"(To everyone) She was such a happy outgoing individual," said husband Steven McMullen. "She was like that when people were there, but when she was on her own she was down.
"She spent her 55th birthday in bed. She wouldn't open her cards or look at anything. She just ignored it."
Mr McMullen found his wife dead in the shed of their home in Blundell Road, Fulwood three days later, after he had return from walking the dog.
Area Coroner Richard Taylor reached a suicide conclusion after hearing Mrs McMullen had referred herself to mental health services in the days before she died.
The inquest was told she admitted in a telephone appointment with the Minds Matter service that she felt like taking her own life. But in a follow-up call with another practitioner just hours later she said she had been reassured and no longer had thoughts of self-harm.
Mrs McMullen, known affectionately as Mrs Mac at the school where she worked for 20 years, had been suffering from anxiety and depression for 14 years, unknown to those outside her family.
She also suffered from an over-active thyroid which she believed could cause dementia in patients after the age of 55, even though there was no real evidence to show that.
"She had read it somewhere years before that when people reached 55 there was more chance of dementia," said husband Steven.
"She obsessed about it all the time. So (reaching) 55 was a very big milestone for her.
"I could reassure her and then she would be fine. But then she was back to normal and obsessive. She had done that for years.
"I had never noticed any sign of self-harm. She never discussed ending her life.
"I didn't see anything like this happening. But on the Monday I came home from work and she was in bed. Her birthday was on the Thursday and while I was walking the dog she called me to say 'I'm going to let you go. You can leave me. I know I'm a nuisance and I'm bothering you.'
"But when I got home she said she was alright now and told me 'forget I mentioned it.'
Coroner Richard Taylor said that as Mrs McMullen approached her 55th birthday her anxieties came to the surface again. But he said that what happened could not have been predicted.
"There had been no indication this was ever going to happen," he said.
Mr McMullen added: "She just couldn't get it (reaching her 55th birthday) out of her head. She had obsessed about it for years and she couldn't cope with it."