Hoarding disorder occurs when a person collects an excessive number of items and stores them in a chaotic manner.

The items often have no monetary value.

Excessive hoarding can interfere with everyday life by blocking access to areas of the home and affecting a person's relationships with friends and family.

Previously classed as a type of OCD (obsessive compulsive disorder), it only became recognised as a medical condition in it's own right earlier this year.

The reasons why someone starts hoarding are not fully understood.

Hoarding can often be a symptom of another condition. For example, someone with mobility problems may be physically unable to clear the huge amounts of clutter they acquire, and people with learning disabilities may be unable to sort and dispose of items.

Mental health problems can also cause compulsive hoarding - those associated include severe depression, psychotic disorders like schizophrenia or OCD (obsessive compulsive disorder).

However, in some cases, hoarding is a condition in itself.

Many people who hoard find it difficult to discard things, thinking: "I may need this someday".

Others may be struggling to cope with a stressful life event, such as the death of a loved one.

Most people with a hoarding disorder have a very strong emotional attachment to the objects they keep.

Hoarding disorders are difficult to treat because often those who hoard don't see it as a problem.

And those who do are reluctant to seek help because they feel ashamed, humiliated or guilty about it.

It's really important to encourage a person who is hoarding to seek help, as their difficulties discarding objects can not only cause loneliness and mental health problems but also pose a serious health and safety or fire risk.

If you think a family member or someone you know has a hoarding disorder, try to persuade them to come with you to see a GP.

This may not be easy, but try to be sensitive about the issue and emphasise your concerns for their health and well-being. Reassure them that nobody is going to go into their home and throw everything out.

If not tackled, hoarding is a problem that could never go away.

An estimated 200,000 Scots are affected by the disorder, and council worker David Woods is one of them.

He was just a university student when he fell in love with learning. So he bought books... and lots of them.

Thirty years on, the 50-year-old council worker lives in a small Edinburgh bungalow with his ever-growing collection: 15,000 books and DVDs surround him on all sides.

"It becomes kind of almost impossible to let go of stuff.

"I didn't think it was a problem. I've kind of done it for a while I think and it's just built up over the years.

"Most of the objects here that I have are books and the thought process is 'what if there's some information in that book that I need to know?' I go into a level of survival.

"I think throwing stuff away gets less painful as you do more of it but it can still kind of bite a little bit. It can still hurt."

On Thursday, October 4, Edinburgh played host to the UK's first major conference looking at the issue, which explored treatments and interventions for the condition.