Aging and the Brain

The Effects of Aging

agingWith aging, we lose brain plasticity, which results in a loss of cognitive function. That’s why a young person with an active, flexible brain, easily latches on to new ideas and simply thinks faster than an older person whose brain has lost plasticity and is more fixed in its patterns. Loss of resilience can, for example, can be counteracted by regular physical activity. The pliability of the brain is reliant on its ability to branch out and connect to new neural circuitry through:

  • the ongoing elimination of old neural cells and natural waste,
  • the ability to utilize glucose and essential nutrients, and
  • the production of new neurons.

Protecting Plasticity

Synaptic Plasticity

Synaptic plasticity is a term that arises frequently in brain research. It refers to the process through which patterns of synaptic activity stimulate changes at synapses. Patterns of synaptic activity or inactivity regulates the amount of communication at the synapse. Synapses can change and the degree of change depends on how much they are used.

Neurotropic Factors

The ability to utilize and put into action essential proteins in the brain is possible through the action of neurotrophic factors. These are molecules produced by the body (biomolecules), mostly peptides and proteins. The three known neurotrophins are brain-derived:

  • brain-derived neurotrophic factor (BDNF),
  • vascular endothelial growth factor (VEGF),
  • and nerve growth factor (NGF).

Neurotrophic factors keep the brain nourished. When they are working well our ability to think and process information stays healthy. When their action is impaired, learning and remembering becomes more difficult, and the brain actually withers and shrinks over time.

Neurotrophic factors are positively affected by a having a healthy diet, being emotional balanced, managing stress and exercising regularly. Negative influences include an unhealthy diet, sedentary lifestyle, tobacco and alcohol use, mood disorders, oxidative stress, emotional imbalances such as excessive fear or anger, chronic pain, deficiencies in certain essential vitamins and in some cases, medications.

Glucocorticoids

In response to signals from the hypothalamus, the adrenal glands secrete glucocorticoids, hormones that produce an array of effects in response to stress. Natural glucocorticoids (also called glucocorticoids, corticosteroids or steroids) are present in almost all organs and tissues, including brain, and effect homeostasis, the body’s ability to adapt to stress, and mediate hormonal activity through the stimulation or suppression of target gene transcription. Glucocorticoids can diffuse through the blood-brain barrier and exert long-term effects on processing and cognition.

Excess chronic stress causes the increased release of glucocorticoids, which in turn causes changes seen in AD patients in glutamate neurotransmission in the prefrontal cortex and the hippocampus, thereby influencing some aspects of cognitive processing. A decrease in the secretion of glucocorticosteroids causes preservation of spatial memory in adults and has also been shown to have neuroprotective effects. Lifelong corticosterone levels determine age-related decline in neurogenesis and memory.

Next: Stress and the Brain