What happens to your neurons as you age?

As we get older it is common to experience difficulties in remembering words, a reduced attention span and ability to focus on more than one task at a time. These signs reflect the many changes that occur in the brain as you age.

Neurons, or nerve cells, receive information from our external environment and from the cells within your body and send this information to the brain. The brain assesses this message against factors such as past experience from memories and the normal range of vital signs (e.g., heart rate, pulse, blood pressure). Then neurons communicate to the rest of the body to execute the appropriate response from the brain. For example, if a cricket ball was headed in your direction, your brain would send various instructions to the body via neurons, including the release of glucose to give you the energy to move and the activation of your leg and arm muscles to get to that ball to catch it.

Types of Neurons

Several types of neurons are responsible for communicating the different categories of information that the brain requires to formulate a plan of action, and these include:

• Sensory neurons – these neurons monitor information from the five senses (touch, sight, taste, smell, and hearing). For example, you touch a hot surface, and the brain then communicates a response through the motor neurons which causes you to quickly remove your hand from the oven tray).
• Motor neurons – these neurons control skeletal and smooth muscles.
• Interneurons – these neurons pass instructions between the sensory and motor neurons.
• Neurons in the brain – numerous subcategories of complex specialist neurons for specific tasks[1].

Structure of Neurons

The structure of a neuron can be likened to an electrical power cord, as essentially neurons are transmitting messages throughout the body in a comparable way to electrical impulses. Dendrites receive information from the body which is communicated through the axon to the axon terminal. The axon terminal then communicates the message to other neurons by releasing chemicals neurotransmitters into the synapse – the space between neurons where neurotransmitters are released and passed to the next neuron. The myelin sheath is a fatty layer that shields the neuron cell to allow the information to be sent quickly and efficiently.

The Aging Neuron

Several structural changes occur in your neurons as you age making it harder for information to be communicated through the nervous system. The size of the neuron reduces, dendrites retract, myelin sheath erode, and the number of synapses reduce[2]. These changes result leads to impaired learning, memory, and cognition, as the brain receives fragmented information in a less orderly and timely fashion.

In our younger years we regularly create new neurons, developing new and complex neural pathways. When we are learning a new skill, like a new language or a musical instrument, thousands of neurons are developing new connections so that these skills can easily be repeated through memory and our motor responses. As we age, the creation of neurons slows, and it becomes harder for us to learn and integrate the memory of how to perform a new task.

Chronic inflammation and neurodegenerative disease can expedite the deterioration of brain function through further damage to our neurons. In Alzheimer’s disease, the main factors are chronic inflammation, amyloid plaques, neurofibrillary tangles and reduced blood flow and oxygen to the brain[3].

• Chronic inflammation is cause by cellular debris and toxins, as the body becomes less efficient at removing them from circulation. This clogs up the brain and causes increased damage to neurons through oxidative stress.
• Amyloid plaques are toxic beta-amyloid proteins which clump together between neurons, scrambling the transmission of information from one neuron to the next.
• Neurofibrillary tangles describe the irregular build-up of tau protein within the neurons. Tau protein is usually responsible for supporting the integrity of the neuron to guide chemicals efficiently through the axon. In Alzheimer’s disease, tau protein breaks away from the structure of the axon, attaching to other tau proteins, creating tangles.
• Blood vessel issues can result from factors such as the build-up of amyloid plaques, hardening of the arteries and mini strokes - all of which reduce nutrients and oxygen reaching the brain and allowing it to function optimally³.

 

Suzy Walsh BBA (Hons)., BNat., mNMHNZ is a Registered Naturopath & Medical Herbalist

 

References:

[1] Types of neurons. (2018, March 26). Queensland Brain Institute - University of Queensland. https://qbi.uq.edu.au/brain/brain-anatomy/types-neurons

[2] Wnuk, A. (n.d.). How the brain changes with age. BrainFacts. https://www.brainfacts.org/thinking-sensing-and-behaving/aging/2019/how-the-brain-changes-with-age-083019

[3] What happens to the brain in Alzheimer's disease? (n.d.). National Institute on Aging. https://www.nia.nih.gov/health/what-happens-brain-alzheimers-disease