The bright side and the dark side of aging

It is well known that aging causes a decline in several domains of cognitive function. Memory tasks, speed processing and the ability to switch from one task to another are examples of cognitive skills with a tendency to diminish, as we grow older. But nevertheless, it is also known that, in the absence of neuropsychiatric pathologies, several other every-day functions tend to remain stable over time (1).

In fact, in modern societies, an increasing number of older adults maintain high levels of satisfaction, personal independence, and a relatively stable health status. Paul B Baltes, who is like a rock star in psychology of aging, described this process as ‘successful aging’ (2,3). I still want to add something more about Paul B Baltes: he was one of the great persons that made it possible the incredibly awesome idea of creating a fellowship funding program in aging research. I still don’t know why, but I was admitted as a postdoc student in that program. I still feel extremely grateful for not having to worry about money at the end of the month.

So, after having stated my deep and selfless admiration for Paul B Baltes and his work, let’s go back to aging. One of the functions that seems to be stable across life span is emotional management. In this field, it has been formulated an influential theory called the “emotional paradox”. This paradox refers to the fact that, despite being proportionally more exposed to emotional adversities (e.g. the loss of significant others, declines in physical strength, increments in the vulnerability to disability), the subjective well-being of healthy older adults is maintained or even increased with age (4,5).

Nevertheless, aging is a highly heterogeneous process, influenced by multiple genetic and environmental factors. As such, it is not surprising that emotional processes present strong differences, even across healthy older individuals.

For example, subjective rates of happiness might be influenced by political and economical population characteristics. Last year, a very cool study observed marked variations across different countries in subjective rates of well-being, with relatively high rates of happiness in high-income English speaking countries, in Latin America and in Caribbean countries, and high rates of unhappiness in several transition countries, such as in Eastern Europe and in countries of the former Soviet Union (6).

Health status is obviously another factor to take into account when studying subjective well-being in aging. Here, I’m going to focus on the role of vascular burden. It seems clear now that vascular factors are associated with lower cognitive outcomes, especially in the domain of mental speed (7). In addition to this, late-life affective symptomatology seems to be closely related to vascular pathology. This phenomenon is also referred to as “vascular depression”. Essentially, the vascular depression hypothesis proposes that vascular risk factors may be associated with the beginning or with the chronicity of depressive symptoms (8). Vascular depression has been associated with several neurological, immunological and cognitive changes (8). Amongst them, the best established is the presence of ischemic lesion burden, observable via white matter hyperintensities. A meta-analysis on 30 studies reported that relative to controls, patients with late-life depression exhibited a more frequent and severe white matter hyperintensities. Interestingly, the same study reported that white matter hyperintensities were more severe in individuals with late-life depression relative to individuals with early-life depression (9). This last finding rises the interesting possibility that late-life depression might constitute a different entity of depressive disorders (9). Complementing this finding, a very recent study in community dwelling older adults has found that severity of white matter hyperintensities seems to predict the development of depressive symptoms (10).

So, to sum up, one should not neglect the deleterious effects of vascular burden in aging. Several studies seem to indicate that vascular factors might compromise subjective well-being in aging. However, there are good news too! Vascular risk factors can be highly influenced by lifestyles. I really want to avoid ending this paragraph writing a list of healthy things to do and unhealthy things to avoid. So, yah know, if you don’t really want to change your unhealthy habits at all, not even for the sake of your future health in 50 years, maybe you should consider moving to a Caribbean or Latin American country. I’m not sure if this last point makes any sense, but it won’t hurt after all!

REFERENCES

  1. Park DC, Reuter-Lorenz P. The adaptive brain: aging and neurocognitive scaffolding. Annu Rev Psychol. 2009; 60:173–96.
  2. Baltes PB. Theoretical propositions of life-span developmental psychology: On the dynamics between growth and decline. Dev Psychol. 1987; 23(5):611–26.
  3. Baltes PB, Baltes PB. On the Incomplete Architecture of Human Ontogeny. Am Psychol. 1997; 52(4):366–80.
  4. Carstensen L. Taking time seriously: A theory of socioemotional selectivity. Am Psychol. 1999; 54:165–81.
  5. Mather M. The emotion paradox in the aging brain. Ann N Y Acad Sci. 2012; 1251: 33–49.
  6. Steptoe A, Deaton A, Stone A a. Subjective wellbeing, health, and ageing. Lancet. 2014; 6736(13):1–9.
  7. López-Olóriz J, López-Cancio E, Arenillas JF, Hernández M, Jiménez M, Dorado L, et al. Asymptomatic cervicocerebral atherosclerosis, intracranial vascular resistance and cognition: The AsIA-Neuropsychology Study. Atherosclerosis. 2013;230(2):330–5.
  8. Taylor WD, Aizenstein HJ, Alexopoulos GS. The vascular depression hypothesis: mechanisms linking vascular disease with depression. Mol Psychiatry. 2013;18(9):963–74.
  9. Herrmann LL, Le Masurier M, Ebmeier KP. White matter hyperintensities in late life depression: a systematic review. J Neurol Neurosurg Psychiatry. 2008;79:619–24.
  10. Park JH, Lee SB, Lee JJ, Yoon JC, Han JW, Kim TH, et al. Epidemiology of MRI-defined vascular depression: A longitudinal, community-based study in Korean elders. J Affect Disord. 2015; 180:200–6.
  11. Vu NQ, Aizenstein HJ. Depression in the elderly: brain correlates, neuropsychological findings, and role of vascular lesion load. Curr Opin Neurol. 2013; 6:656–61.
  12. Byrne GJ, Pachana N a. Anxiety and depression in the elderly: do we know any more? Curr Opin Psychiatry. 2010; 23(6):504–9.
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