The brains of people with seasonal depression may be too efficient at bundling away a key chemical, a new study suggests.The finding in people with (SAD) backs the prevailing theory about the biochemical causes of depression, and could give clues into new ways to treat the condition.

The prevailing theory of depression is that affected people do not have enough of certain neurotransmitters called monoamines – serotonin, norepinephrine, and dopamine – in the spaces between neurons. Most modern antidepressants work by blocking the absorption of these neurotransmitters back into the cell.

However, there is little agreement on why levels are inadequate in the first place. It could be that depressed people produce lower volumes of the neurotransmitters, or they could break them down too rapidly. Or it could be that the neurotransmitters are removed from the junction between neurons, called the synaptic cleft, too quickly.

Matthaeus Willeit and Harald Sitte at the University of Vienna in Austria and their colleagues now have evidence for the last of these – that serotonin is being removed too efficiently …

Source: Allison Motluk, New Scientist