Women with postpartum depression experience smell differently
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Women with postpartum depression experience smell differently than other women do, according to a study published by Scientific Reports.
These findings add further evidence that postpartum depression and major depression are different, requiring separate research and medical attention, according to the researchers.
“Postpartum depression has been long regarded as a sub-category of major depressive disorder. This condition has a very poor diagnostic rate, with many women suffering from it without being properly diagnosed or treated,” author Mei Peng, PhD, MA, of the University of Otago Department of Food Science in New Zealand, said in a press release.
“Recently, the scientific community has been questioning whether postpartum depression should be studied and treated separately from major depression following insights into the different effect each disorder has on neurobiology,” Peng said.
Between 6% and 12% of women experience pregnancy-related depression during pregnancy, the researchers said, with more than 20% affected after having a baby.
The researchers believe that resolving the status of postpartum depression may have important implications for its diagnosis, treatment, policy and research.
“Our world-first study helps show the sensory symptoms related to postpartum depression are very different from those of major depression. Specifically, patients with postpartum depression show normal olfactory sensitivity, whereas patients with major depressive disorder would show substantially declined olfactory sensitivity,” said Peng.
The multidisciplinary study compared the olfactory abilities of 18 prenatal and 21 postnatal (up to 1 year following pregnancy) depressed mothers to a healthy cohort of 39 women.
The researchers used the Edinburgh Postnatal Depression Scale (EPDS) before the olfactory test sessions to gauge the participants’ levels of postpartum depression.
Also, each participant attended two olfactory testing sessions of an hour each 4 weeks apart. The olfactory testing consisted of an olfactory threshold test, odor hedonistic testing and odor intensity testing.
The Snap & Sniff Olfactory Test System (Sensonics International), which includes five blank-odor pens and 15 odorant pens, was used for the olfactory threshold testing with a staircase testing paradigm.
During the odor hedonistic testing, participants rated three “pleasant” and three “unpleasant” odors based on the Labelled Affective Magnitude Scale, which uses a hundred points across nine anchors from the “greatest imaginable like” to the “greatest imaginable dislike.”
Similarly, participants used the Labelled Magnitude Scale to rate the strength and intensity of those same six odors on a hundred-point range with seven anchors spanning from “no sensation” and “barely detectable” to “very strong” and “strongest imaginable.”
There was no difference between each group’s ability to detect smells during the olfactory threshold testing, the researchers said, with no significant relationship between odor threshold and EPDS score (r = 0.13).
However, the testing revealed a significant negative relationship between EPDS and hedonistic ratings for the three “unpleasant” odors — odorant one (r = 0.41; P < .001), odorant three (r = 0.44; P < .001) and odorant five (r = 0.42; P < .001) — suggesting that individuals with higher depression scores are more likely to rate these odors worse.
The researchers also found a negative relationship between EPDS and intensity ratings for one of the “pleasant” and two of the “unpleasant” odorants, as participants with higher EPDS scores experienced lower odor intensities. Those included odorant two (r = 0.34; P = .002), odorant three (r = 0.32; P = .004) and odorant five (r = 0.30; P = .008).
“These findings imply that postpartum depression is associated with alterations in higher-order olfactory perception, but not early processing of odors,” said Peng.
The researchers noted that odor identification and discrimination were outside of the scope of their analyses. Also, many participants were overweight, and previous studies have suggested a close relationship between obesity and olfactory function.
The researchers now are seeking funding to further study the effects of pregnancy on women’s long-term quality of life.