What happens to your brain as you age

Early Development and Birth

• Brain formation begins approximately two weeks post-conception with the thickening of the neural plate, which folds into a tube by week four to establish the nervous system.
• From the closure of the neural tube, the brain generates hundreds of neurons per minute.
• At birth, the brain contains approximately 100 billion neurons, an excess that is subsequently shed before adulthood.
• Newborns possess an average of 2,500 synapses per neuron, increasing to roughly 15,000 within the first few years as neurons mature.
• High synapse density in early childhood facilitates rapid learning of languages and musical instruments and establishes long-term developmental impacts based on early experiences.

Childhood Plasticity and Myelination

• Between ages three and ten, the brain prunes unused connections to improve efficiency, a process governed by neuroplasticity where synaptic strength adjusts based on usage.
• Myelin insulation begins at birth, starting at the back of the brain and moving forward, accelerating information transmission between brain areas.
• Synaptic strengthening or weakening replaces the older scientific view of fixed synaptic levels, allowing the brain to absorb new information efficiently.

Adolescent Development and Risk

• Brain growth halts in adolescence, but development continues through asynchronous maturation of brain regions.
• The ventral striatum (reward center) develops faster than the prefrontal cortex (associated with self-control and rationality), creating a developmental mismatch.
• Major changes in the limbic system contribute to increased mood swings in teenagers compared to adults.
• The developmental gap between emotion-driven and rational brain areas explains why teenagers are statistically more likely to engage in risky behaviors and experience addiction.
• Increased activity in the ventromedial prefrontal cortex during puberty enhances social interaction skills and friendship formation but may also increase susceptibility to social anxiety.
• Post-puberty, the prefrontal cortex expands and forms new connections linking emotional and motor centers.

Adulthood and Peak Development

• The brain reaches full structural development in the 30s.
• White matter volume peaks at approximately age 40 before declining.
• Older adults often utilize both cerebral hemispheres for short-term memory tasks, whereas younger adults typically rely on the left hemisphere.
• Research indicates middle-aged and older adults minimize negative emotional impacts; the amygdala shows reduced reactivity to negative images in older adults compared to the equal positive/negative response in younger adults.
• This resilience is attributed to decades of experience activating specific neural pathways for similar situations.

Menopause and Aging Effects

• Menopause alters brain energy consumption due to estrogen changes, causing symptoms such as hot flushes and mood swings.
• Post-menopausal white matter volume decreases without recovery.
• Despite white matter loss, post-menopausal brains exhibit higher structural connectivity between specific regions, potentially increasing regional efficiency.
• Cognitive slowing typically begins in the 30s and 40s, influenced by genetics, before accelerating in the 60s and 70s.
• In later life, the cerebral cortex thins, particularly in the frontal lobe and hippocampus, which govern memory, emotion, and navigation.
• Aging is associated with a reduction in white matter and fewer chemical messengers (dopamine, serotonin), leading to slower cognitive processing.

Death and Post-Mortem Activity

• Recording of a patient's brain waves during a heart attack revealed a spike in high-cognitive function brain waves immediately prior to death.
• This activity suggests the brain may recall significant life events just before death, potentially explaining near-death experiences.
• Brain activity can persist for several minutes after cardiac arrest, indicating that brain function does not cease immediately upon death.