Elderly patients who take anti-depressants run a higher risk of getting osteoporosis, it has emerged.

Two studies found that patients who used drugs such as Prozac and Seroxat developed thinner bones.

Depression affects up to one in five people at some point in their lives, with 1.5million Britons aged 16 to 75 suffering from it at any time.

Last year, 16.2 million prescriptions for antidepressants called SSRIs were given, up from 14.7million in 2005. The selective serotonin re-uptake inhibitors can trigger suicidal thoughts and self-harm and are not recommended for patients under 18.

The U.S. studies were published in the journal Archives of Internal Medicine.

Researchers from Oregon Health and Sciences University looked at almost 6,000 men aged at least 65.

And scientists at the University of Minnesota in Minneapolis investigated 2,722 women with an average age of 80.

Both found hip bone density fell among patients taking SSRIs. The drugs inhibit a protein that carries serotonin, a brain chemical involved in depression. But the same protein also exists in bones.