cognition
Meaning of cognition: Because separate brain networks handle memory, attention and language, one of them can fail while the others carry on working normally.
Definition of cognition
Cognition covers the mental processes by which information is taken in, held, worked on and used: attention, memory, language, visual and spatial judgment, reasoning, and the planning and self-monitoring grouped together as executive function. It is not one ability but several, each supported by different brain networks, which is why they can be affected separately.
What are the main areas of cognition?
Splitting cognition into domains is not academic tidiness. It is what allows a change to be located, because each domain leans on different parts of the brain.
| Domain | What it does | How a problem shows |
|---|---|---|
| Attention | Selects and sustains focus | Losing the thread, distractibility, fluctuating alertness |
| Learning and memory | Records and retrieves experience | Repeating questions, misplacing objects, forgetting recent events |
| Language | Understands and produces speech | Word finding difficulty, muddled grammar, trouble following speech |
| Visuospatial ability | Judges shape, distance and layout | Getting lost in familiar places, difficulty dressing or drawing |
| Executive function | Plans, sequences, inhibits, self-corrects | Poor organization, impulsivity, difficulty with multi-step tasks |
What changes cognition?
The list is long because so much converges on the brain. Degenerative diseases, stroke, head injury, a brain tumor and demyelinating conditions such as multiple sclerosis damage tissue or connections directly. Thyroid disease, vitamin B12 deficiency, poorly controlled diabetes and kidney or liver failure act through the body's chemistry. Sedative and anticholinergic medications, alcohol, untreated pain, poor sleep and depression all reduce measured performance without any structural damage at all, which is why they are considered before a lasting condition is assumed.
How is delirium different from dementia?
Both reduce cognitive performance and they are easily confused. Delirium comes on over hours or days, fluctuates through the day, disturbs attention and alertness first, and usually follows an acute trigger such as infection, a new drug or surgery; it can resolve once the trigger is dealt with. Dementia develops over months to years, progresses steadily, and leaves alertness intact until late. The two also coexist, and delirium occurs more readily in someone whose cognition was already impaired.
Used in a sentence
Cognitive testing was performed to evaluate memory and attention following the head injury.
Good to know
Cognition covers several distinct abilities rather than one, so a change in memory does not imply that attention, language or planning are affected in the same way or to the same degree.
Word origin
Where “cognition” comes from
From Latin cognitio, derived from cognoscere, meaning to know or become acquainted with, itself formed from co- and gnoscere, to know.