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Human Development · Chapter 13

The Cognitive Continuum

Forgetting a name is not the same as forgetting the way home. In late adulthood, thinking naturally slows — but a measurable, disease-driven decline is something else entirely. Drag the slider to move from normal aging, through mild cognitive impairment, to dementia, and watch the one thing that truly separates them: whether a person can still live independently.

Normal Aging

Ventricles — fluid spaces that enlarge as tissue is lost Hippocampus — the memory center that shrinks
Diagnostic term —
Normal Agingdrag the slider to explore
Drag along the cognitive continuum  →
Objective testing—
Daily independence—
Meets dementia criteria—
The dividing line is function. Normal aging is not a disease — thinking slows, but daily life is untouched. MCI is a decline that testing can measure, yet the person still lives independently. The moment cognitive loss robs someone of independent daily living — managing money, medications, or getting around safely — it becomes dementia. MCI is also the window to search for reversible causes: depression, thyroid disease, B12 deficiency, or medication effects.