Experts already know that people with major depression are at increased risk of age-related diseases such as cancer, diabetes, obesity and heart disease.
This might be partly down to unhealthy lifestyle behaviors such as alcohol use and physical inactivity.
Depression can make us physically older by speeding up the ageing process in our cells
But scientists suspect depression takes its own toll on our cells.
To investigate, Josine Verhoeven from the VU University Medical Centre in the Netherlands, along with colleagues from the US, recruited 2,407 people to take part in the study.
More than one third of the volunteers were currently depressed, a third had experienced major depression in the past and the rest had never been depressed.
The volunteers were asked to give a blood sample for the researchers to analyze in the lab for signs of cellular ageing.
The researchers were looking for changes in structures deep inside cells called telomeres.
Telomeres cap the end of our chromosomes which house our DNA. Their job is to stop any unwanted loss of this vital genetic code. As cells divide, the telomeres get shorter and shorter. Measuring their length is a way of assessing cellular ageing.
People who were or had been depressed had much shorter telomeres than those who had never experienced depression. This difference was apparent even after lifestyle differences, such as heavy drinking and smoking, were taken into account.
Furthermore, the most severely and chronically depressed patients had the shortest telomeres.
Dr. Josine Verhoeven and colleagues speculate that shortened telomeres are a consequence of the body’s reaction to the distress depression causes.
“This large-scale study provides convincing evidence that depression is associated with several years of biological ageing, especially among those with the most severe and chronic symptoms,” they say.
However, it is unclear whether this ageing process is harmful and if it can be reversed.
Anna Friel has revealed she relies on the “Master Cleanse” regime, which sees food replaced with a mixture of cayenne pepper, maple syrup and lemon juice, to stay slender.
Anna Friel, 36, told Grazia magazine: “It’s amazing. I’ve been drinking it for two months and I feel so much better and my skin has really benefitted.
“If you’re vain, as you get older you start thinking, <<I’ve got to do everything I can to save my skin>>. I’ve tried everything!”
Other celebrity fans of the Master Cleanse include Gwyneth Paltrow and Beyoncé, who lost 20 lbs in just two weeks ahead of filming her movie Dreamgirls by sticking to the plan.
Beyoncé said of the diet: “I lived on water, cayenne pepper and maple syrup for 14 days. It was tough; everyone was eating and I was dying.”
Anna Friel relies on the Master Cleanse regime, which sees food replaced with a mixture of cayenne pepper, maple syrup and lemon juice, to stay slender
Restricting her food allowance isn’t the only way Anna Friel maintains her youthful allowance, as she told the publication she is also a fan of the celebrity favorite “vampire facelift”.
She said: “Vampire facials involve taking two vials of blood from your arm and re-injecting it back into your skin.
“It’s meant to help your skin heal itself and boosts collagen. It makes my skin really glowy and tight again.”
In addition, Anna Friel has regular Cryoderm treatments prior to red carpet appearances – a treatment which involves the skin being warmed up with a machine to stimulate collagen production and therefore reduce the signs of wrinkles – as well as giving herself a DIY version of the method at home.
The actress explained: “I always have a Cryoderm treatment before a red carpet. People say I look really good afterwards.
“I also do the old-fashioned method at home, where I fill my sink with ice cubes and hold them on my face for a minute.”
Ageing is clearly a huge concern for Anna Friel, who said that she will try absolutely anything in a bid to stay looking young.
Anna Friel added: “I felt sick recently because I found one or two grey hair and I read that curry leave help maintain your hair color, so I mix them with hot water and drink it as a tea.
“I’m always searching for pure, natural skin products and Trilogy is great for that too. Their Everything Balm is fantastic.”