Brain ageing is inevitable to some extent, but not uniform; it affects everyone, or every brain, differently. Slowing down brain ageing or stopping it altogether would be the ultimate elixir to achieve eternal youth. Are there steps, we can take to reduce the rate of decline?
At around 3 Kg in weight, the human brain is a staggering feat of engineering with around 100 billion neurons interconnected via trillions of synapses. Throughout our lifetime our brain changes more than any other part of our body. From the moment the brain begins to develop in the third week of gestation to old age, its complex structures and functions are changing, networks and pathways connecting and severing.
During the first few years of life, a child’s brain forms more than 1 million new neural connections every second. The size of the brain increases fourfold in the preschool period and by age 6 reaches around 90% of adult volume.
The frontal lobes – the area of the brain responsible for executive functions, such as planning, working memory and impulse control – are among the last areas of the brain to mature, and they may not be fully developed until 35 years of age.
As we age, all our body systems gradually decline – including the brain. “Slips of the mind” are associated with getting older. People often experienced those same slight memory lapses in their 20s and yet did not give it a second thought.
Older individuals often become anxious about memory slips due to the link between impaired memory and Alzheimer’s disease. However, Alzheimer’s and other dementias are not a part of the normal ageing process.
Common memory changes that are associated with normal ageing include 1. Difficulty learning something new: Committing new information to memory can take longer. 2. Multitasking: Slowed processing can make processing and planning parallel tasks more difficult. 3. Recalling names and numbers: Strategic memory that helps the memory of names and numbers begins to decline at age 20. 4. Remembering appointments: Without cues to recall the information, appointments can be put safely in storage and then not accessed unless the memory is jogged.
While some studies show that one-third of older people struggle with declarative memory (memories of facts or events that have been stored and can be retrieved), other studies indicate that one-fifth of 70-year-olds perform cognitive tests just as well as their 20-year-old counterparts.
Scientists are currently piecing together sections of the giant puzzle of brain research to determine how the brain subtly alters over time to cause these changes. General changes that are thought to occur during brain ageing include:
1. Brain mass: Shrinkage in the frontal lobe and hippocampus – areas involved in higher cognitive function and encoding new memories – starting around the age of 60 or 70 years.
2.Cortical density: Thinning of the outer-ridged surface of the brain due to declining synaptic connections. Fewer connections may contribute to slower cognitive processing.
3.White matter: White matter consists of myelinated nerve fibres that are bundled into tracts and carry nerve signals between brains cells. Myelin is thought to shrink with age, and as a result, slow processing and reduce cognitive function.
4.Neurotransmitter systems: Researchers suggest that the brain generates less chemical messengers with ageing, and it is this decrease in dopamine, acetylcholine, serotonin, and norepinephrine activity that may play a role in declining cognition and memory and increased depression.
Several brain studies are ongoing to solve the brain-ageing conundrum, and discoveries are being frequently made. Recently, researchers from Albert Einstein College of Medicine in New York revealed in a mouse study that stem cells in the brain’s hypothalamus likely control how fast ageing occurs in the body.
“Our research shows that the number of hypothalamic neural stem cells naturally declines over the life of the animal, and this decline accelerates ageing,” says Dr. Dongsheng Cai, Ph.D., professor of molecular pharmacology at Einstein. “But we also found that the effects of this loss are not irreversible. By replenishing these stem cells or the molecules they produce, it’s possible to slow and even reverse various aspects of ageing throughout the body.”
Injecting hypothalamic stem cells into the brains of normal old mice and middle-aged mice, whose stem cells had been destroyed, slowed or reversed measures of ageing. The researchers say this is a first step toward slowing the ageing process and potentially treat age-related diseases.
While many questions remain regarding the ageing brain, research is making progress in illuminating what happens to our cognitive functions and memory throughout our lifetime, and it is emphasizing ways we can preserve our mental abilities to improve our quality of life as we advance into older adulthood.