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   Biochemical cause of seasonal depression (SAD) confirmed by researchers   
      
   Date:   
   October 20, 2014   
   Source:   
   European College of Neuropsychopharmacology (ECNP)   
      
   Woman looking sad in fall scene (stock image). SAD affects a significant   
   amount of people as daylight levels drop in autumn.   
   Credit: © djtaylor / Fotolia   
      
      
   New research confirms why some people suffer from the winter blues while   
   others get through the winter without any problems. A longitudinal study from   
   a group of researchers from the University of Copenhagen has found that that   
   people with Seasonal    
   Affective Disorder (SAD) show significant seasonal differences in the way they   
   regulate the neurotransmitter serotonin in comparison to the majority of the   
   population. This work is being presented at the ECNP congress in Berlin.   
   SAD affects a significant amount of people as daylight levels drop in autumn.   
   At Northern European latitudes (for example all of Scandinavia, Glasgow and   
   Moscow) around 1 person in 6 suffers from SAD.   
      
   The researchers scanned 11 SAD patients and 23 healthy individuals using   
   Positron Emission Tomography; they were able to show significant summer to   
   winter differences in the levels of the serotonin transporter (SERT) protein;   
   SAD patients showed higher    
   levels of SERT in the winter months, corresponding to a greater removal of   
   serotonin in winter.   
      
   Serotonin (also known as 5-HT) is a neurotransmitter which affects mood, in   
   fact many anti-depressant drugs, such as SSRIs (Selective Serotonin Reuptake   
   Inhibitors, such as Prozac) work by allowing serotonin to be retained in the   
   synapse where it exerts    
   its effects.   
      
   Lead researcher, Brenda Mc Mahon said "We believe that we have found the dial   
   the brain turns when it has to adjust serotonin to the changing seasons. The   
   serotonin transporter (SERT) carries serotonin back into the nerve cells where   
   it is not active, so    
   the higher the SERT activity the lower the activity of serotonin. Sunlight   
   keeps this setting naturally low, but when the nights grow longer during the   
   autumn, the SERT levels increase, resulting in diminishing active serotonin   
   levels. Many individuals    
   are not really affected by SAD, and we have found that these people don't have   
   this increase in SERT activity, so their active serotonin levels remain high   
   throughout the winter."   
      
   The SAD patients had an average 5% higher SERT level in the winter compared to   
   the summer, whereas the healthy participants on average showed no significant   
   change.   
      
   Commenting for the ECNP, Professor Siegfried Kasper (Vienna) said "SERT   
   fluctuations associated with SAD have been seen in previous studies, but this   
   is the first study to follow patients through summer and winter comparisons.   
   It seems to offer    
   confirmation that SERT is associated with SAD"   
      
   Story Source:   
   The above story is based on materials provided by European College of   
   Neuropsychopharmacology (ECNP). Note: Materials may be edited for content and   
   length.   
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   Cite This Page:   
   MLA APA Chicago   
   European College of Neuropsychopharmacology (ECNP). "Biochemical cause of   
   seasonal depression (SAD) confirmed by researchers." ScienceDaily.    
      
   ScienceDaily, 20 October 2014.    
      
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