The Brain, Too, Has Its Midlife Crisis. How Do These Changes Relate to the Risk of Dementia in Old Age?

Gradual Deterioration or Rapid Decline?

Psychologists studying age-related changes in mental processes believe that a gradual decline in mental abilities begins as early as 20–30 years of age.

When assessing short-term memory, it appears that the rate of change over time is particularly swift and unstable during middle age. This means that in some otherwise healthy individuals, memory deteriorates rapidly, while others may even improve it. This suggests that the brain undergoes significant transformation during this period.

Several brain structures change during middle adulthood. These include the hippocampus, an area critical for forming new memories. The hippocampus gradually shrinks in adulthood, and this process accelerates in midlife. Sharp changes in the size and function of the hippocampus may account for problems with short-term memory.

The Important White Matter

The brain’s functioning is ultimately enabled by white matter, composed mainly of axons connecting individual neurons. These connections mature gradually throughout adulthood, linking areas of the brain responsible for cognitive functions such as memory, logical reasoning, and language processes. The network formed by white matter also manages sensory processes, such as the processing of visual stimuli.

A Well-connected Community

Just as societal elites form circles of influence, different areas of the brain also connect. Well-organised communication between these areas allows us to perform complex tasks and make strategic decisions.

It appears that the brain reaches its peak connectivity precisely when we enter middle age. The period around 50 years of age is often even considered ideal for some major decisions. Soon afterwards, however, the brain’s network begins to disintegrate.

During midlife, many neural connections reach a tipping point from gaining volume to starting to lose it. This means that signals and information can no longer be transmitted as quickly. Around the same time, reaction times also begin to worsen. The function of the sensory network gradually deteriorates during adulthood, but the decline of the cognitive network accelerates in middle age.

Overly Focused on the Oldest Brains

Some neuroscientists believe that research has focused for too long on brain changes in advanced old age, when problems are most noticeable. By then, however, it is often too late for intervention. Middle age could be a period during which early risk factors for later cognitive decline, such as dementia, might be identified. Early intervention should also be conducted during this period.

How to Detect Risk?

But will it be possible to detect the risk of dementia without complex imaging techniques? The answer may lie in a simple blood test. Researchers from Johns Hopkins University and the University of Mississippi have uncovered a link between the presence of inflammatory molecules in the blood and changes in cognitive function.

The prospective observational ARIC study (Atherosclerosis Risk in Communities) assessed the inflammatory score in over 12,000 participants with an average age of 57, using fibrinogen concentration, C-reactive protein, clotting factors, and white blood cell counts.

It was found that participants in the highest quartile of this score experienced a 7.8% sharper cognitive decline after 20 years compared to peers in the lowest quartile of inflammation scores. Age-related systemic inflammation is therefore likely to play a significant role in cognitive decline processes.

Staying Forever Young…

It appears that ‘biological age’, measured through easily accessible and inexpensive clinical tests, is more important for information about future health than an individual’s chronological age. Middle age may be more important for the health of our brain than we realise. The good news, however, is that the brain’s biological age can be influenced, for example, through physical activity.

Editorial Team, Medscope.pro

Sources:

1. Dohm-Hansen Allard S., Nolan Y. The middle-aged brain changes a lot – and it’s key to understanding dementia. The Conversation, 2024 Mar 19. Available from: https://theconversation.com/the-middle-aged-brain-changes-a-lot-and-its-key-to-understanding-dementia-225412
2. Samanez-Larkin G. R. Financial decision making and the aging brain. Association for Psychological Science, 2013. Available from: https://www.psychologicalscience.org/observer/financial-decision-making-and-the-aging-brain
3. Walker K. A., Gottesman R. F., Wu A. et al. Systemic inflammation during midlife and cognitive change over 20 years: The ARIC Study. Neurology 2019; 92 (11): e1256–e1267, doi: 10.1212/WNL.0000000000007094.