Cognition

Adult hippocampal neurogenesis (AHN) is how new neurons are born from neural stem and progenitor cells. They form in the subgranular zone of the hippocampal dentate gyrus (DG),…

Amyloid-β (Aβ) is a family of small protein fragments, 36 to 43 amino acids long. They are snipped out of a bigger protein (amyloid precursor protein, APP) by two enzymes (β- and…

Amyloid precursor protein (APP) is a membrane-spanning protein. It is coded on chromosome 21 and found widely in your brain and nerves. How it is cut decides everything. There…

BDNF (brain-derived neurotrophic factor) is a growth-factor protein. It supports neuron survival, the formation of synapses, and (at least in animals) the birth of new neurons in…

The blood-brain barrier (BBB) is a tightly controlled wall between your bloodstream and your brain. It is built from specialized endothelial cells lining the brain's capillaries,…

Cerebral blood flow (CBF) is how much blood your brain gets per minute, measured in mL per 100 g of tissue per minute. Three systems regulate it: autoregulation, sensitivity to…

Cerebral small vessel disease (CSVD) is damage to your brain's tiniest blood vessels: the small arteries, arterioles, capillaries, and venules. It shows up on brain scans as a…

Cognitive reserve is your brain's functional adaptability. Yaakov Stern developed and formalized the concept. He built on earlier 'brain reserve' work by Katzman and colleagues…

CSF biomarkers for Alzheimer's are proteins measured in your spinal fluid (via a lumbar puncture) that mirror the core brain pathologies. As amyloid gets locked into plaques,…

The default mode network (DMN) is a set of connected brain regions that switch on when your mind is at rest, and switch off during focused tasks. The core hubs include the medial…

Flow, described by psychologist Mihaly Csikszentmihalyi, is a state of deep absorption in a challenging task that is well matched to your skill. In flow, your self-awareness…

Fluid versus crystallized intelligence is a split within the Cattell-Horn-Carroll (CHC) framework. It separates two broad mental abilities that age very differently. Fluid…

Gait speed, usually measured over a 4- or 6-meter walk at a comfortable pace, is one of the strongest and cheapest functional markers of whole-body aging. A single number rolls…

Hippocampal volume measures the size of the hippocampus. That is the brain region central to memory consolidation and spatial navigation. Atrophy rates vary by cohort and method.…

Ikigai is a Japanese concept, loosely translated as a sense of purpose or a reason for being. It covers everyday sources of meaning, like your relationships, your routines, and…

Lewy bodies are clumps that build up inside your brain cells, made mostly of a misfolded protein called α-synuclein. Friedrich Lewy first described them in 1912, and they are the…

Loneliness is the subjective feeling of being socially disconnected. It is now a recognized risk factor for heart disease, dementia, and early death. Meta-analyses by…

Microglia are your brain's resident immune cells. They come from yolk-sac precursors that colonize the brain early in embryo development, and they renew themselves without help…

Mild cognitive impairment (MCI) sits between normal aging and dementia. By Petersen's criteria, it means tests show a real cognitive decline, but you still handle daily life on…

Mindfulness is a trained practice. You bring open, non-judgmental attention to the present moment, usually through meditation. Randomized trials show modest but consistent…

The Mini-Mental State Examination (MMSE), introduced by Folstein, Folstein, and McHugh in 1975, is a 30-point cognitive screening test. It checks orientation, registration,…

The Montreal Cognitive Assessment (MoCA), developed by Ziad Nasreddine and published in 2005, is a 30-point, 10-minute bedside screening test. It covers visuospatial/executive…

Neuroinflammation is when your brain's innate immune system, mainly microglia and astrocytes, gets activated, by protein clumps, injury, or the sterile signals of aging. It…

Neuroplasticity is your brain's lifelong ability to rewire itself, both its structure and its synaptic connections, in response to learning, experience, and injury. It is what…

Polyvagal theory, proposed by Stephen Porges in 1995, makes a claim about your vagus nerve. It says two distinct vagal branches evolved in mammals: a newer 'ventral-vagal'…

The prefrontal cortex (PFC) is the front part of your brain that runs your 'executive' functions: working memory, mental flexibility, impulse control, and planning ahead. (It…

Presenilin 1 (PSEN1) and presenilin 2 (PSEN2) are nine-pass membrane proteins. They form the catalytic core of the gamma-secretase complex, together with nicastrin, APH-1, and…

Synaptic plasticity is the activity-driven change in the strength of connections between your neurons. It is considered the cellular basis of learning and memory. The classic…

Tau is a protein that normally stabilizes the internal skeleton of your nerve cells, by binding to microtubules. In Alzheimer's and related 'tauopathies', it goes wrong. It gets…

TREM2 (triggering receptor expressed on myeloid cells 2) is a receptor that sits across the cell membrane. In the brain, almost only microglia (the brain's immune cells) carry…

Vascular dementia is cognitive decline severe enough to disrupt your daily life, caused by problems with the brain's blood supply. It is the second most common dementia after…

White matter hyperintensities (WMH) are patches that light up abnormally bright on certain brain MRI scans (T2-weighted and FLAIR), within the brain's white matter. They are not…