Glossary
A working dictionary of brain health terms. Plain English up top, technical references underneath. 16 entries so far, growing.
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C
Cerebrospinal fluid
The clear fluid that surrounds and cushions the brain and spinal cord, circulates through the ventricles, and plays a key role in waste clearance from the brain.
Cognitive reserve
The brain's accumulated resilience against pathology — built over a lifetime through education, cognitive engagement, and social activity — which allows some people to sustain function despite significant structural brain changes.
Cortical thickness
The thickness of the brain's outer grey-matter ribbon (the cortex), measured millimetre-by-millimetre across its surface from a structural MRI.
D
Default mode network
A set of brain regions that are most active when the mind is at rest and not focused on an external task — linked to self-referential thinking, memory retrieval, and mind-wandering.
Dementia / Alzheimer's disease
Dementia is a syndrome of progressive cognitive decline severe enough to impair daily life; Alzheimer's disease is its most common cause, characterised by amyloid plaques, tau tangles, and gradual neurodegeneration.