Mechanisms and potential treatments for declining olfactory function and neurogenesis in the ageing brain
Broad, K. D.
Olfaction, Ageing, Neurogenesis, Depression, Flavour
The role of olfactory function in maintaining quality of life and as a potential surrogate marker of neurogenic
activity in the elderly brain is an underappreciated topic. The olfactory system is complex and is unusual in that
its function is maintained by neurogenesis at multiple sites throughout the lifetime of an organism, which in
humans may be over 80 years in length. Declines in olfactory function are common with advancing age and this
is associated with reductions in the quality of life, the perception of flavour and neurogenesis. These reductions
in neurogenesis may simply be a consequence of advancing age or may reflect the nascent development of
underlying neurological dysfunction. There are a number of potential therapeutic interventions that can result
in a gain of olfactory function, these range from behavioural modification, to dietary supplementation and pharmaceutical
intervention but they are all thought to work in part by increasing hippocampal and olfactory neurogenesis.
This review discusses the mechanisms underlying olfactory decline in the elderly, reviews a number
of potential strategies for improving olfactory function and hypotheses that increasing the rate of neurogenesis
in the ageing brain would improve the quality of life not only by improving olfaction but by improving a range of
cognitive processes that are dependent on neurogenesis including mood.