How the Brain Works The Facts Visually Explained by DK (z-lib.org)

THE PHYSICAL BRAIN

The Aging Brain

Young brain

Young brains look plump; the ridges

covering the surface of the cortex

almost touch. The fluid-filled ventricles

in the center of the brain are small,

and the subarachnoid space, which

surrounds and cushions the brain,

forms a thin layer.

Ventricles are

regular-sized

hollow spaces

Healthy basal

ganglia free of

abnormalities

Enlarged ventricles

Severe

cortical

shrinkage

Normal size of

subarachnoid

space

White-matter

tracts are in

good condition

The Aging

Brain

With age, some abilities decline as neurons

degenerate and the brain decreases in

volume. In those neurons that remain,

impulses may travel more slowly.

The shrinking brain

As we age, there is a natural reduction of neurons

as they degenerate, and the brain as a whole shrinks

5 to 10 percent in volume. This is partially due

to decreased blood flow to aging brains. The fatty

myelin that insulates the axons of neurons also decays

with age, leaving brain circuits less efficient at

transmitting information, which can lead to problems

with memory recall and maintaining balance.

KEY

Gray

matter

Basal

ganglia

White

matter

Ventricles

Aging and happiness

Aging might seem like a bad thing, but studies have

shown that as we get older, our feelings of happiness

and well-being increase, while levels of stress and

worry decrease. Older adults’ brains seem to be better

at focusing on the positive. They are more likely to

remember happy than sad pictures and spend more

time looking at happy faces than angry or upset ones.

Ups and downs

A study found younger

and older people

reported higher levels

of well-being than

those in middle age.

Happiness levels

rose steadily from

age 50 onward.

Alzheimer’s disease, the most common form of dementia

(see p.200), is linked to the buildup of proteins in the

brain, which clump into plaques and tangles. Eventually,

affected brain cells die, causing memory loss and other

symptoms. Scientists do not know yet whether the

proteins cause the disease or are a symptom of it, and

drugs to break them down have not helped patients.

ALZHEIMER’S DISEASE

HEALTHY BRAIN ALZHEIMER’S BRAIN

WELL-BEING

AGE

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