Subjective age (SA) refers to how an individual perceives and experiences themselves as being younger or older than their chronological age, which is their actual age based on birth date.
The concept of SA has been increasingly recognized in ageing research as a crucial construct due to its relationship with various late-life health outcomes, including physical health, self-rated health, life satisfaction, depressive symptoms, cognitive decline, dementia, hospitalisation, and frailty. Although chronological age is a primary factor that contributes to these outcomes, research has shown that SA can be an independent predictor of individual differences in the ageing process.
A recent study aimed to explore the relationship between SA and the neurobiological process of ageing. The study enrolled 68 healthy older adults who underwent a SA survey and magnetic resonance imaging (MRI) scans. The results showed that individuals who perceived themselves as younger than their real age had larger grey matter volumes in certain brain regions, including the inferior frontal gyrus and the superior temporal gyrus, and younger predicted brain age. The findings suggest that the subjective experience of ageing is closely related to the process of brain ageing, indicating that SA could be an important marker of late-life neurocognitive health. The findings were published in the journal Frontiers in Aging Neuroscience.
However, the study also had several limitations that need to be considered. Firstly, the age-predicting model showed relatively lower accuracy among the subjects, which may have resulted from several factors, including the difference in sample characteristics, data collection protocols, and modelling parameters. Secondly, the study used a coarse measurement of SA, which may have resulted in the loss of information regarding the extent to which participants feel about their age within each categorized group. Thirdly, the interpretation of SA could have been clearer if both the aspects of social influence and interoceptive awareness were questioned separately. Finally, the study was cross-sectional in nature, and therefore, the temporal relationships between SA and the neurobiological process of ageing could not be fully understood.
In conclusion, the study highlights the importance of SA as a predictor of late-life health outcomes and underscores the need for further research to explore the neural mechanisms of SA and its relationship with the ageing process. Future longitudinal studies are necessary to better understand the temporal relationships between SA and brain ageing, as well as to distinguish the specific neural mechanisms of interoceptive perception and social influence.
