Researchers at Johns Hopkins University School of Medicine in the USA have found that people with mild cognitive impairment show a loss of serotonin transporters compared to a healthy control group.
Whilst the degeneration of the serotonin system as a part of aging and in Alzheimer’s Disease is well known, there is little evidence for its demise in mild cognitive impairment.
In this study, 28 adults with mild cognitive impairment and 28 healthy, cognitively normal matched control adults underwent a number of brain imaging procedures.
People with mild cognitive impairment show a loss of serotonin transporters
The results showed that serotonin transporter levels in patients with mild cognitive impairment were 10-19 percent lower in the cortical regions and the raphe nuclei and 10-38 percent lower in the striatum and the thalamus, compared with the control group.
The researchers note that the loss of serotonin transporters in mild cognitive impairment may have “a significant impact on brain function and behaviour” given their widespread distribution in the brain and previous evidence identifying serotonin degeneration in Alzheimer’s Disease.
They conclude that serotonergic agents could be potentially used to prevent cognitive decline and the emergence of neuropsychiatric symptoms in patients with mild cognitive impairment.
However, they admit that further investigation is needed to establish whether serotonin degeneration is a causative factor or a downstream effect of Alzheimer’s Disease.
Smith GS et al. Molecular imaging of serotonin degeneration in mild cognitive impairment. Neurobiol Dis. 2017;105:33-41.