Classification & Assessment in Psychiatry · Paper A
Neuropsychological tests (overview)
Neuropsychology uses specific pen-and-paper or computerised tests to pin down exactly which brain function has failed, rather than relying on a vague sense that something is wrong. Take two patients who both seem to struggle with memory: one cannot form new memories at all, while the other simply cannot organise a plan. The right test tells you which is happening, because each test targets a different function. The referral question ('is this memory or planning?') decides which test is used, not a single blanket cognitive screen. Choosing the wrong test wastes the assessment, since a memory test cannot expose a planning deficit and vice versa.
Premorbid (before illness) IQ is estimated with the National Adult Reading Test (NARTNational Adult Reading Test, a test that estimates a person's earlier level of intelligence from how they read words.Read more →), which asks the patient to read aloud irregularly-spelled words such as 'aisle', a skill that resists early dementia even when other abilities decline. A patient with a NART-estimated premorbid IQ well above their current WAIS score shows a gap that is itself evidence of decline. Current IQ uses the WAIS (Wechsler Adult Intelligence Scale), covering verbal and performance subtests. Frontal/executive function (planning, shifting between rules) is tested with the Wisconsin Card Sorting Test, verbal fluency, and Trail Making B-minus-A. Subtracting the time for the simpler Trail A from Trail B isolates the specific cost of shifting attention, since Trail A alone only measures visual scanning speed. E.g., a patient scoring poorly on Trail Making B but normally on Trail A shows an isolated set-shifting problem, not a general slowing.
A referral that just says 'assess this patient's cognition' is not specific enough to act on. Neuropsychology exists to answer a sharper question: exactly which brain function has failed, and by how much? Every test in this concept targets one specific domain — intelligence, memory, executive function, or visuospatial skill — and matching the right test to the right complaint is the entire skill being examined here.
A neuropsychological test is a standardised pen-and-paper or computerised task with a known scoring system, used to measure one specific mental function. PREMORBID (before illness) ability means how a person's brain worked before whatever is now being investigated — a dementia, a head injury, a psychiatric illness. CURRENT ability is how the brain performs right now. The gap between the two, when it exists, is itself diagnostic information.
A common trap is picking a single 'general' cognitive test and assuming it covers everything. It does not. Suppose a patient scores normally on a brief bedside screen but their family insists something is wrong with planning and organising daily tasks — a screen weighted toward memory and orientation can miss a pure executive-function problem entirely. The referral question must drive test selection, not habit.
Start from the idea that the brain is not one uniform organ; different regions do different jobs. Memory depends heavily on the medial and . Planning, shifting between rules, and inhibiting an automatic response depend on the . Copying a shape and finding your way around a room depend on parietal and occipital regions. Because damage can be localised, a test that only samples one of these systems will only reveal damage to that system — a normal score elsewhere tells you nothing about the others.
PREMORBID IQ is estimated with the National Adult Reading Test (), which asks the patient to read aloud a list of irregularly spelled words such as 'aisle' or 'chord'. Reading such words correctly relies on stored word-recognition memory, a skill that resists early dementia even once other abilities are declining, which is exactly why it estimates what IQ used to be rather than what it is now.
CURRENT IQ uses the WAIS (Wechsler Adult Intelligence Scale), a lengthy battery covering verbal comprehension, working memory, processing speed and perceptual reasoning, scored against age-matched norms.
FRONTAL and EXECUTIVE function — planning, shifting between rules, inhibiting an automatic response — is tested with several tools. The Wisconsin Card Sorting Test asks the patient to sort cards by a rule that changes without warning; someone with frontal damage keeps sorting by the old rule (). Verbal fluency asks the patient to name as many words as possible starting with a given letter, or belonging to a given category, in one minute. Trail Making Test Part B asks the patient to connect alternating numbers and letters (1-A-2-B-3-C…); subtracting the time taken for the simpler Part A (numbers only) from the time for Part B isolates the specific cost of shifting attention between two rule sets, rather than just measuring general processing speed.
VISUOSPATIAL MEMORY is tested with figure-copying tasks such as the Rey-Osterrieth Complex Figure: the patient copies a complicated geometric figure, then — without warning — is asked to draw it again from memory minutes later. A patient who copies accurately but cannot reproduce the figure from memory shows a specific visuospatial memory deficit, not a general intellectual decline.
The exam loves testing whether a candidate can tell these tools apart by what they measure, not just their names. measures premorbid ability and is resistant to early decline; WAIS measures current ability and IS sensitive to decline. Trail Making B-minus-A isolates shifting specifically, unlike Trail B alone, which is also slowed by simple motor speed. The Wisconsin Card Sorting Test measures set-shifting; a related test, the Hayling Sentence Completion Test, instead measures response inhibition — the ability to suppress an obvious completion of a sentence — a different executive skill entirely.
Neuropsychological testing is one part of a broader dementia or cognitive-impairment investigation. NICE guidance on dementia recommends structured cognitive assessment alongside history from an informant, blood screening to rule out reversible causes such as thyroid disease or vitamin B12 deficiency, and imaging (usually MRI) to look for structural change. Detailed neuropsychological testing is typically requested by a memory clinic when a bedside screen is inconclusive or when the pattern of deficits does not fit a single obvious diagnosis.
Results shape management directly. A pattern dominated by memory loss with preserved executive function points toward typical Alzheimer's disease and its usual first-line management (cholinesterase inhibitors such as donepezil, per NICE). A pattern dominated by early executive and personality change instead raises suspicion of frontotemporal dementia, which changes the medication choices and the practical safety advice given to the family. Cognitive rehabilitation therapy — structured practice and compensatory strategies for the specific deficit identified — is planned around exactly which domain testing showed was impaired.
When a vignette names a specific test, ask what single function it targets before reading the result. The examiner is testing whether you know the test's job, not just its name.
Each neuropsychological test targets one specific brain function, so the referral question — not a single blanket screen — should decide which test is used.