Women taking the contraceptive
pill 'more likely to be depressed'
Behind the Headlines
Friday September 30 2016
The pill contains artificial hormones
"Are you on the Pill? You're more likely to be depressed: Women who
use contraception are up to 70% more likely to be on antidepressants,"
reports the Mail Online.
The news is based on a study by researchers in Denmark to see whether
hormonal contraceptive methods were associated with depression. More
than 1 million women aged 15 to 34, with no prior history of depression,
were included in the study.
The researchers found that, compared to non-users, those who took the
pill were 23% more likely to use antidepressants.
However, it's important to note this study is not able to prove that the
contraceptive methods are responsible for the depression, only to find
possible links to investigate further.
The researchers don't advise that women should stop using their
contraception, just that further studies are needed. If this association is
found to be true, depression may have to be added as a possible side
effect of hormonal contraception.
Where did the story come from?
The study was carried out by researchers from the University of
Copenhagen and was funded by the University of Copenhagen and the
Lundbeck Foundation.
The study was published in the peer-reviewed medical journal JAMA
Psychiatry.
The study authors revealed that Dr Kessing had consulted for Lundbeck
and AstraZeneca and receiving honoraria for this work, while Dr
Lidegaard received honoraria for talks within the past three years from
Exeltis.
The story was reported accurately in the media, with The Telegraph
stating: "The Danish study didn't aim to show that the Pill directly causes
depression. But it does point to a worrying association between women
taking the contraceptive and those also being prescribed an
antidepressant." This is useful to note as this kind of study is not able to
prove cause and effect.
What kind of research was this?
This was a large prospective cohort study which aimed to investigate
whether the use of hormonal contraception is associated with future use
of antidepressants and diagnosis of depression.
This type of study is able to provide possible links between the exposure
and outcome, but is not able to prove that one causes the other. It
remains possible that other factors, such as concerns over pregnancy, or
taking regular medication, might contribute to the outcome.
What did the research involve?
The researchers used data from the National Prescription Register and
the Psychiatric Central Research Register in Denmark.
Women and girls aged between 15 and 34 years of age, living in
Denmark, were followed up from January 1 2000 to December 2013.
They were excluded from the study if they had:
• a previous diagnosis of depression
• been prescribed antidepressants
• another major psychiatric diagnosis
• cancer
• venous thrombosis
• infertility treatment
Contraceptive methods were categorised by oestrogen type and dose,
progesterone type and the method of contraception. Data was collected
from the National Prescription Register.
Data for the use of antidepressants was collected using two outcome
measures:
• collecting a prescription for antidepressants
• being diagnosed with depression at any inpatient or outpatient
psychiatric department in Denmark
Non-users were defined as those who never used hormonal
contraceptives, plus former users.
What were the basic results?
The analysis included 1,061,997 women, with an average age of 24 years.
During follow-up, 55.5% of women were current or recent users of
hormonal contraception. A total of 133,178 first prescriptions of
antidepressants and 23,077 first diagnoses of depression were detected
during follow-up.
The researchers compared users of hormonal contraception with nonusers and found more users had been prescribed antidepressants or
diagnosed with depression.
They calculated the increase in risk of using antidepressants according to
contraceptive method as:
• oral contraceptives – 23% (relative risk [RR] 1.23 (95% confidence
interval [CI], 1.22 to 1.25))
• progestogen-only pill – 34% (RR 1.34 (95% CI, 1.27 to 1.40))
• contraceptive patch (norgestrolmin) – 100%, (RR 2.0 (95% CI, 1.76 to
2.18))
• vaginal ring (etonogestrel) – 60% 1.6 (RR (95% CI, 1.55 to 1.69))
• levonorgestrel intrauterine system (IUS) – 40% (RR 1.4 (95% CI, 1.31 to
1.42))
Similar figures were found for depression diagnoses.
The researchers also found the risk of depression decreased with age.
Adolescents using combined oral contraceptives had an 80% increased
risk of antidepressant use (RR 1.8 (95% CI, 1.75 to 1.84)) and those using
progesterone-only pills a 120% higher risk (RR 2.2 (95% CI, 1.99 to 2.52)).
How did the researchers interpret the results?
The researchers concluded that the "use of hormonal contraception,
especially among adolescents, was associated with subsequent use of
antidepressants and a first diagnosis of depression, suggesting
depression as a potential adverse effect of hormonal contraceptive use."
Conclusion
This was a large prospective cohort study which aimed to investigate
whether using hormonal contraception is associated with the future use
of antidepressants and a diagnosis of depression.
The researchers compared users of hormonal contraception with nonusers and found users were more likely to be prescribed antidepressants
and diagnosed with depression.
However, there are a few important points to consider about the results,
such as:
• this study is not able to prove that the contraceptive methods are
responsible for the depression – only to find possible links to
investigate further
• some of the associations are based on a comparatively small number
of events
• the risk of using antidepressants and being diagnosed with depression
peaks at approximately two to three months of contraceptive use,
but then begins to fall
The researchers tested for a range of other things that might explain the
results. For example, they looked at whether doctors were more likely to
prescribe hormonal contraception to women who were already low in
mood, or whether the initiation of a sexual relationship might influence
the risk of depression. They found nothing that could easily explain the
link that was shown across all age groups and types of contraception.
Further studies are required to prove this link. If the link is proven in
future studies, depression may have to be added as a possible side
effect of hormonal contraception.