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Almost a third of UK adults suffer from some form of seasonal affective disorder (SAD), according to a YouGov survey of 2,031 people commissioned by The Weather Channel. Meanwhile research presented during a European College of Neuropsychopharmacology meeting offers new insights into this condition.

In the Weather Channel survey, 57 per cent of those interviewed said that their overall mood is worse in winter than summer. Sixty-six per cent said their mood in the winter makes them feel less active and 8 per cent reported suffering from SAD. A further 21 per cent suffered subsyndromal SAD.

€Previous studies have suggested that the rate of SAD is around 3 to 4 per cent of the population. This finding of a rate of 8 per cent of British adults is quite striking and suggests a bigger problem than previously thought,€ comments psychologist Professor Lance Workman from the University of South Wales. Twenty-one per cent reporting subsyndromal SAD €is also concerning€, he says, and suggests that, €rather than this being a rare problem, changes of mood in the winter months affect nearly one in three of the British population€.

During the ECNP meeting, researchers from the University of Copenhagen reported significant seasonal differences in serotonin regulation when they scanned 11 SAD patients and 23 healthy people using positron emission tomography. SAD patients showed higher levels of serotonin transporter (SERT) €“ by, on average, 5 per cent €“ in the winter than the summer. Healthy people showed, on average, no significant seasonal change.

'Found the dial'

€We believe that we have found the dial the brain turns when it has to adjust serotonin to the changing seasons,€ said lead researcher Brenda McMahon. €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.€