Common antidepressents are less effective at high altitudes, rodent study suggests

May 31, 2018, University of Utah
Credit: CC0 Public Domain

Three common antidepressants – Paxil (paroxetine), Lexapro (escitalopram), and Prozac (fluoxetine) – could be less effective at high elevations, suggests research involving lab rats and led by scientists at University of Utah Health.

When rats were placed in conditions that simulate moderate-high altitudes, the three pharmaceuticals failed to suppress behaviors that model human . By contrast, another antidepressant, Zoloft (sertraline), worked under these conditions. The results of tests with the four drugs – all of which fall in the class of antidepressants known as serotonin reuptake inhibitors (SSRIs) – are published in the May online edition of Pharmacology, Biochemistry and Behavior.

"Being at altitude can worsen levels of depression and lower the response to SSRIs," said Shami Kanekar, research assistant professor of psychiatry and lead author on the study. "We may need to be more careful about which antidepressants are prescribed to people living at altitude." Future studies will need to determine if these selective effects of SSRIs in animals are also seen in people.

Previous work has shown links between living at higher altitudes and susceptibility to depression. Rates of depression and suicide are particularly high in Utah and other states in the Intermountain West region of the United States where elevations are considerably higher than in the rest of the country. Similar trends are also seen in countries such as Austria and Peru that have large populations living at high elevation.

Connections between altitude and depression have also been documented in tests with where conditions can be carefully controlled. Kanekar found that rats acclimated to 4,500 feet, or in hypobaric chambers mimicking conditions at 10,000 feet, were more likely to display depression-like behaviors than those in chambers calibrated to sea level conditions. Depression was evaluated by validated methods, including the inclination to swim and climb.

The current study adds an important element to the discussion by demonstrating that of four SSRIs tested, only Zoloft significantly and consistently lessened signs of depression seen at altitude. Moreover, there were clear differences between females and males in both antidepressant response and depression-like behavior at altitude.

Despite being within the same class of antidepressants, individual SSRIs have different pharmacological profiles, potentially explaining their varied effects.

"Utah has very high rates of both depression and anxiety. In many instances, long-term treatment is required but does not work well," says the study's senior author Perry Renshaw, professor of psychiatry. "This work suggests that only some antidepressants are likely to be effective at altitudes higher than 2,000 feet."

While the current study investigated short-term impacts of the drugs and changes in altitude, it remains to be determined whether responses to also differ over the long-term in people.

If the findings hold true, they could also have implications for individuals with diseases that affect breathing such as asthma, sleep apnea, and chronic obstructive pulmonary disease (COPD). These so-called hypoxic conditions lower amounts of oxygen in the bloodstream, mimicking impacts of low oxygen environments at . Patients with these conditions are also susceptible to increased rates of depression and suicidal behavior.

In addition to Kanekar and Renshaw, Chandni Sheth, Hendrik Ombach, Paul Olson, Olena Bogdanova, Matthew Petersen, Chloe Renshaw, Young-Hoon Sung, and Kristen D'Anci are authors on the study.

Explore further: Thin air, high altitudes cause depression in female rats

More information: Shami Kanekar et al. Hypobaric hypoxia exposure in rats differentially alters antidepressant efficacy of the selective serotonin reuptake inhibitors fluoxetine, paroxetine, escitalopram and sertraline, Pharmacology Biochemistry and Behavior (2018). DOI: 10.1016/j.pbb.2018.05.002

Related Stories

Thin air, high altitudes cause depression in female rats

March 26, 2015
In a novel study, University of Utah (U of U) researchers have shown that hypobaric hypoxia (the reduced oxygen experienced at high altitude) can lead to depression.

Could living at high altitude increase suicide risk? Evidence suggests possible treatments

March 10, 2018
High-altitude areas—particularly the US intermountain states—have increased rates of suicide and depression, suggests a review of research evidence in the Harvard Review of Psychiatry.

Male depression may lower pregnancy chances among infertile couples, study suggests

May 17, 2018
Among couples being treated for infertility, depression in the male partner was linked to lower pregnancy chances, while depression in the female partner was not found to influence the rate of live birth, according to a study ...

Insights into depression could aid development of new treatments

February 26, 2018
Fresh insights into changes in the brain linked to depression could pave the way for new therapies.

Do antidepressants lead to chronic use?

January 3, 2018
Data from Netherlands point to the chronic use of antidepressant drugs in general practice in a study published in the current issue of Psychotherapy and Psychosomatics. Antidepressant use is highly prevalent. Research has ...

Depression and anxiety may reduce chances of IVF pregnancy

March 7, 2016
Depression and anxiety, and not necessarily the use of antidepressant medication, are associated with lower pregnancy and live birth rates following in vitro fertilisation, according to a large register study from Karolinska ...

Recommended for you

Self-perception and reality seem to line-up when it comes to judging our own personality

December 14, 2018
When it comes to self-assessment, new U of T research suggests that maybe we do have a pretty good handle on our own personalities after all.

Levels of gene-expression-regulating enzyme altered in brains of people with schizophrenia

December 14, 2018
A study using a PET scan tracer developed at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital (MGH) has identified, for the first time, epigenetic differences between the brains of individuals ...

Researchers discover abundant source for neuronal cells

December 13, 2018
USC researchers seeking a way to study genetic activity associated with psychiatric disorders have discovered an abundant source of human cells—the nose.

Video game players frequently exposed to graphic content may see world differently

December 13, 2018
People who frequently play violent video games are more immune to disturbing images than non-players, a UNSW-led study into the phenomenon of emotion-induced blindness has shown.

New genetic clues to early-onset form of dementia

December 13, 2018
Unlike the more common Alzheimer's disease, frontotemporal dementia tends to afflict young people. It accounts for an estimated 20 percent of all cases of early-onset dementia. Patients with the illness typically begin to ...

How teens deal with stress may affect their blood pressure, immune system

December 13, 2018
Most teens get stressed out by their families from time to time, but whether they bottle those emotions up or put a positive spin on things may affect certain processes in the body, including blood pressure and how immune ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.