In the first year after being told by a doctor that they have acne, patients' risk for a diagnosis of major depressive disorder spikes by more than 60 per cent compared to the general population, according to a new study.

Dermatologists and other doctors treating acne should keep an eye on patients' mood symptoms as well, and start treatment or make a psychological referral if depression is present, the authors write in the British Journal of Dermatology.

"The idea for the current study came from another recently published study we did looking at the mental health effects of the acne drug isotretinoin (Accutane)," lead author Isabelle Vallerand, a Calgary researcher, told Reuters Health by email.

"Over the past few years, there have been numerous reports that isotretinoin has been linked to psychiatric disorders," said Vallerand, Vallerand, a researcher with the Community Health Sciences department of the Cumming School of Medicine at University of Calgary.

"Our recently published systematic review did not find an increased risk of psychiatric disorders among people treated with isotretinoin, but we wondered if acne itself may be contributing to mental illness."

5.6 million Canadians suffer from acne

Acne includes whiteheads, blackheads, pimples, cysts and nodules that affect the face, shoulders, back, chest and upper arms. In Canada, it affects nearly 20 per cent of Canadians, or 5.6 million people, including about 90 per cent of adolescents, according to the Canadian Dermatology Association.

A Canadian study of nearly 500 patients with acne that was published in the British Journal of Dermatology also found even having mild acne can bring on feelings of low self- esteem, depression and suicidal thoughts, the CDA said on its website.

While it is intuitive that acne can have negative effects on mood, Vallerand said, the study team wanted to assess whether there was an increased risk of true clinical depression.

Using a large U.K. database of medical records, the researchers analyzed information on patients seven to 50 years old, focusing on 134,437 people with a new acne diagnosis and 1,731,608 similar patients without acne. After following both groups for up to 15 years, researchers found that among acne patients, the probability of developing major depressive disorder was 18.5 per cent, while in the general population, it was 12 per cent. The risk was highest in the first year after a new acne diagnosis and then tapered off, the authors note.

"We found that acne increased the risk of developing clinical depression by 63 per cent in the first year following an acne diagnosis and that this risk remained elevated for five years after the initial acne diagnosis," Vallerand said.

Overall, acne patients had 46 per cent higher risk for major depression than the comparison group. Women outnumbered men among the acne patients, and women were also more likely to develop depression. The authors did not have information about the severity of patients' acne, but speculate that more severe cases might lead to greater depression risk.

Nor did they know what acne medications the patients were using, other than those on isotretinoin.

'More than just a skin blemish'

"While it has been known for many years that people with acne might have a lower mood resulting from their skin, this is the first study to show conclusively that acne can be more than just a skin blemish, and can have a substantial impact on mental health in the form of clinical depression," Vallerand said.

"We believe that health-care providers treating patients with acne should firstly be aware that acne is a risk factor for developing major depressive disorder and that they should encourage any of their patients with acne to feel comfortable raising any mental health concerns to their attention, as these should be taken seriously."

Physicians treating patients with acne should also help to co-ordinate mental-health interventions for patients who develop depression, when needed, she added.

Vallerand received funding for the study from Alberta Innovates MD-PhD Studentship and from the Mach-Gaensslen Foundation of Canada.