Seasonal variation in human brain serotonin transporter binding

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Seasonal variations in mood and energy are common, with reduced well-being during winter.
• Brain serotonin is crucial for regulating mood, sleep, and energy balance.
• The molecular basis for seasonal changes in serotonin function remains largely unknown.

Purpose of the Study:

• To investigate seasonal fluctuations in serotonin transporter binding in the human brain.
• To explore the relationship between serotonin transporter binding and daily sunshine duration.

Main Methods:

• Positron emission tomography (PET) using a carbon-11 labeled tracer to measure serotonin transporter binding potential.
• Assessment of binding potential in healthy volunteers over a four-year period.
• Correlation analysis with meteorological data, specifically sunshine duration.

Main Results:

• Serotonin transporter binding potential was significantly higher in fall and winter compared to spring and summer.
• Higher binding potential values correlated negatively with the duration of daily sunshine across all brain regions studied.
• These findings indicate a clear seasonal pattern in serotonin transporter density.

Conclusions:

• Serotonin transporter binding potential exhibits significant seasonal variation in the human brain.
• Increased serotonin transporter density, observed in darker months, is linked to reduced synaptic serotonin.
• This seasonal regulation of serotonin transporter density represents a novel physiological mechanism potentially explaining seasonal mood and behavioral changes.