In the run-up to OCD Week (February 20-26), Lisa Salmon reveals how obsessive compulsive disorder causes behaviours that can rule a person's life and experts from OCD Action explain how the condition can be dealt with.
There's nothing wrong with keeping the surfaces in your house clean. But when you spend hours bleaching them every day, and don't leave the house because you're frightened of the germs outside, you may have obsessive compulsive disorder (OCD).
A problem suffered by between 1-2% of the population, OCD can control a person's life, perhaps because they're cleaning all the time, repeatedly checking doors are locked and appliances switched off, or performing mental rituals in the belief it will stop them harming someone they love.
In the approach to OCD Week (February 20-26), the charity OCD Action hopes to raise awareness that OCD is a serious mental condition, which can ruin people's lives.
Joel Rose, director of OCD Action, explains that while many individuals experience obsessions, compulsions and anxiety similar to OCD, the symptoms must be profound to warrant a diagnosis.
"OCD can be a misused term," he says. "Those who are diagnosed are at the very severe end, and not just a slightly quirky person.
"It's like the difference between being sad and being clinically depressed. True OCD is when it's taking over your life."
The Royal College of Psychiatrists say the disorder has three main parts: thoughts that make you anxious (obsessions), the anxiety you feel, and the things you do to reduce your anxiety (compulsions).
While people can have compulsions without having obsessional thoughts, very often they occur together. Carrying out a compulsion reduces the person's anxiety and gives them an urge to perform it again.
"The obsessions are repeated, unwanted thoughts or mental pictures that cause distress, and keep coming back into your mind even though you try to resist them," explains consultant psychiatrist Dr Paul Blenkiron.
The most common obsessions are a fear of contamination by germs, of behaving in a sexually inappropriate way or being aggressive - for example a mother worrying she'll kill or abuse her baby.
"Compulsions are the actions you do to try and make things all right, like checking or cleaning," continues Dr Blenkiron. "Unfortunately, these only work for a short time and actually keep the problem going by becoming an unbreakable habit.
"Imagine you're convinced that someone you love will be killed in an accident today unless you touch the door handle three times. This is what it's like to have OCD."
Dr Blenkiron says OCD can affect someone's life so severely they're less likely to marry and can have more difficulty functioning in their work, and social life, than people with physical conditions such as diabetes.
Sufferers often think they're going mad, but Dr Blenkiron stresses: "People with OCD are not dangerous or out of control - quite the reverse is true."
He says it's unusual for sufferers to need to go into hospital, as OCD can be successfully treated in the community.
OCD Action says sufferers have the condition for an average of 12 years before they seek treatment, often because it takes them a long time to find the courage to get help.
Treatment involves 'talking therapy' cognitive behavioural therapy (CBT) and drugs, normally antidepressant selective serotonin reuptake inhibitors (SSRIs).
Dr Blenkiron says CBT or medication will help about six or seven out of every 10 people.
CBT often involves a treatment called Exposure and Response Prevention, in which sufferers repeatedly face their anxieties. So if they have a germ fear, they'll touch a dustbin lid but resist the temptation to wash their hands afterwards.
Dr Blenkiron points out research has shown a change in activity and blood flow in the 'overactive' areas of the OCD brain, before and after CBT.
"They're back to normal again," he explains.
There's much debate about the causes of OCD, but the Royal College of Psychiatrists suggest that stress brings on about one in three cases. Hereditary factors could also be important and an imbalance of the chemical serotonin in the brain has been identified in long-term sufferers.
In addition, if you're a neat, meticulous, methodical person with high standards, you may be more likely to develop the disorder.
Many famous names are said to display OCD-like tendencies, including football star David Beckham and tennis ace Rafael Nadal.
Beckham reportedly insists on lining up his shirts according to their colour, and his wife Victoria says he's obsessive about symmetry and order throughout their home.
Similarly, every time Nadal plays a match, he takes a sip from each of his water bottles, then carefully lines them up so their labels all face the same way.
But it's not just sports personalities who display obsessive compulsive behaviour. Movie star Cameron Diaz is said to open doors with her elbows to avoid touching germ-infested doorknobs, and admits to scrubbing her Hollywood home scrupulously and washing her hands many times a day.
However, Rose stresses there's a vast scale of OCD behaviour, and points out: "Whenever it's said that a celebrity has OCD, they've obviously placed themselves somewhere along the OCD scale far enough to talk about it, but not so far that it stops them being an international sports or film star," he says.
"It's about the impact it has on your life."
Could you have OCD?
According to The Royal College of Psychiatrists, those with OCD may have suffer from some or all of the following problems...
:: Recurring unpleasant thoughts.
:: Repeated horrible mental pictures - perhaps seeing yourself doing something uncharacteristically violent.
:: Constant doubts, such as wondering whether you've caused an accident or left the door unlocked.
:: An inability to make simple decisions.
:: A need for 'perfectionism' and everything to be in the right order.
:: Regular feelings of anxiety, fear, guilt or depression, which can be relieved by carrying out certain behaviours.
:: Routinely thinking alternative 'neutralising' thoughts, such as counting, praying or repeating a special word, to correct obsessional thoughts.
:: Performing rituals, such as washing your hands or arranging objects in a particular way, frequently.
:: Hoarding useless and worn-out possessions.
:: Making repeated requests for reassurance from others.
:: For more information on OCD, visit OCD Action at www.ocdaction.org.uk or call 0845 390 6232