British scientists have shed new light on the development of dementia in the synapses of the brain.
Synapse loss is a key feature of dementia, explain Dr Mike Ashby and colleagues at Bristol University, UK.
They say: "It is unclear whether synaptic dysfunction precedes degenerative phases of the disease."
They carried out tests on mice with tauopathy-associated dementia and found that that, even before any decrease in synapse density, there is "abnormal turnover of cortical axonal boutons and dendritic spines".
They add in yesterday’s Cell Reports that: "Strikingly, tauopathy drives a mismatch in synapse turnover; postsynaptic spines turn over more rapidly whereas presynaptic boutons are stabilised. This imbalance between pre- and post-synaptic stability coincides with reduced synaptically-driven neuronal activity in pre-degenerative stages of the disease."
Dr Ashby said: "Our ability to make effective new drugs has been hampered by the fact that we don’t yet fully understand the causes of this debilitating group of diseases.
"Because neurons are so closely dependent on their synaptic partners, it is possible that the changes in synapse stability could be actually part of the reason that neurons begin to die. If this is true, then it points towards new therapeutic strategies based on treating these very early abnormalities in synaptic behaviour."
Commenting on the study, Dr Rosa Sancho of Alzheimer’s Research UK said: "This new study adds weight to the growing body of evidence suggesting that synapses become disconnected before nerve cells themselves die. By using sophisticated microscopes, the Bristol team has gained valuable new insight into the stability of synapses and how this affects communication between nerve cells. These interesting findings will help inform future research into drugs that could help keep nerve cells healthy for longer."
Jackson, J. et al. Altered synapse stability in the early stages of tauopathy. Cell Reports 29 March 2017
Leave a Reply