New research from King’s College London and The Open University could help explain why memory in old age is much less flexible than in young adulthood.
Researchers conducted experiments in mice demonstrated that there were drastic differences in how memories were stored in old age compared to young adulthood. These differences, at the cellular level, meant that it was much harder to modify the memories made in old age.
The study led by Professor Karl Peter Giese, from the Institute of Psychiatry, Psychology and Neuroscience at King’s College London was published in the journal Current Biology and funded by the UK Biotechnology and Biological Science Research Council.
Memories are stored in the brain by strengthening the connections between nerve cells, called synapses. Recalling a memory can alter these connections, allowing memories to be updated to adapt to a new situation. Until now researchers did not know whether this memory updating process was affected by age.
The researchers trained young adult and aged mice in a memory task, finding that the animals’ age did not affect their overall ability to make new memories. However, when analysing the synapses before and after the memory task, the researchers found fundamental differences between older and younger mice.
New memories were laid down via a completely different mechanism in older animals compared to younger ones. Further, in older mice the synaptic changes linked to new memories were much harder to modify than the changes seen in younger mice.
The basic biological processes for laying down memories is shared by mammals, so it is likely that memory formation in humans follows the same processes discovered in mice.
Professor Giese said: ‘Our results give a fundamental insight into how memory processes change with age. We found that, unlike in the younger mice, memories in the older mice were not modified when recalled. This ‘fixed’ nature of memories formed in old age was directly linked to the alternative way the memories were laid down, which our research revealed.’
Professor Giese suggests that ageing should be taken into consideration when treating patients with PTSD, since confronting and modifying traumatic memories is a core feature of some psychological treatments such as trauma-focused cognitive behavioural therapy. [APBN]