It is well established that seasons can affect mood. But a new study by researchers from Hungary claims the season during which we are born may influence our risk of developing mood disorders later in life.

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The season during which we are born could influence our risk of mood disorders in adulthood, according to researchers.

The research team was led by Zoltan Rihmer of Semmelweis University in Budapest, Hungary, and their findings were disclosed recently at the European College of Neuropsychopharmacology (ECNP) Congress in Germany by presenting author Xenia Gonda.

Seasonal affective disorder (SAD) is possibly the most well-known mood disorder triggered by the changing seasons. During autumn and winter months, individuals with SAD can experience depressive symptoms – such as sadness, anxiety, feelings of hopelessness and guilt, and even suicidal thoughts. These symptoms usually lift in the spring and summer months.

SAD can occur at any point in life. But can the risk of such disorders be influenced by the season during which we are born?

According to Gonda, biochemical studies have indicated that the season a person is born in may affect their levels of dopamine and serotonin – neurotransmitters that can influence mood – which can be detected in adulthood. “This led us to believe that birth season may have a longer-lasting effect”.

For their study, the researchers analyzed more than 400 participants. They looked at the birth season of each participant before assessing their personality traits in adulthood.

They found that participants born in summer were much more likely to have swift, frequent changes between cheerful and sad moods – referred to as a cyclothymic temperament – compared with those born in winter.

Participants born in spring and summer were much more likely to have a hyperthymic temperament – defined as being extremely positive and cheerful with high energy levels – compared with those born in autumn or winter.

Those born in autumn, however, were much less likely to have a depressive temperament than participants born in winter, while those born in winter were less likely to have an irritable temperament than those born in spring, summer or autumn.

Commenting on their findings, Gonda says:

Basically, it seems that when you are born may increase or decrease your chance of developing certain mood disorders. We can’t yet say anything about the mechanisms involved. What we are now looking at is to see if there are genetic markers that are related to season of birth and mood disorders.”

Prof. Eduard Vieta, of the ECNP, notes that it is well known that a person’s temperament is influenced by genetic and environmental factors, but the findings from Rihmer and team suggest that birth season also plays a role. “And the finding of ‘high mood’ tendency (hyperthymic temperament) for those born in summer is quite intriguing,” he adds.

Last month, Medical News Today reported on a study by researchers in Israel, which found that the season during which a baby is born may influence motor development in its first year of life.