Classification & Assessment in Psychiatry · Paper A
Cognitive examination
Cognitive-screening stems are really domain-mapping puzzles, not pass-or-fail verdicts on the whole brain. A patient may copy shapes well but fail delayed recall, or manage orientation but struggle with trail-making. The exam trick is to identify which domain the task probes, then recognise which named screen includes that task.
The MMSE (Mini-Mental State ExaminationA brief, widely used bedside test that scores overall cognitive function.Read more →) is scored out of 30 and samples orientation, registration, attention and calculation, recall, language, and simple visuospatial copying. It does not include clock drawing. The MoCA (Montreal Cognitive AssessmentA brief bedside cognitive test that is more sensitive than the Mini-Mental State Examination to mild impairment.Read more →) is also scored out of 30 but is more sensitive to mild cognitive impairment and executive dysfunction, partly because it includes tasks such as trail-making and clock drawing. ACE-III (Addenbrooke's Cognitive Examination III) is scored out of 100 and gives a broader profile across attention, memory, verbal fluency, language, and visuospatial abilities. Cognitive screening supports assessment; it does not by itself diagnose dementia.
Bedside cognitive tests are not interchangeable. Each one samples a specific mental domain, orientation, attention, memory, language, or visuospatial function, and each named test has a specific structure the exam expects you to recognise from a description alone, before it even names the test.
A cognitive DOMAIN is one distinct category of mental function that can be impaired independently of the others. The MMSE () is a 30-point bedside screening tool. The MoCA (Montreal Cognitive Assessment) and the ACE-III (Addenbrooke's Cognitive Examination, third edition) are longer, more detailed tools designed to be more sensitive to milder impairment. MILD COGNITIVE IMPAIRMENT (MCI) is a measurable decline in cognition that is not severe enough to impair activities of daily living, the feature that distinguishes it from dementia.
A patient can pass one domain perfectly and still have a real, disabling impairment in another. Suppose a patient copies a clock face perfectly, showing intact visuospatial function, but cannot recall three simple words after five minutes: that pattern points specifically to a memory deficit, and the intact clock-drawing does not rule it out. Each domain must be tested separately; a preserved skill in one area never excuses skipping another.
Cognition is not a single faculty; it is built from separable systems, attention, memory encoding and retrieval, language production and comprehension, and visuospatial construction, each depending on different brain regions. A good bedside battery deliberately samples each system with a short task, so that a deficit in one system cannot hide behind normal performance in another. This is exactly the same underlying logic as detailed neuropsychological testing, just compressed into a tool that takes minutes rather than hours.
The MMSE, maximum 30 points, tests orientation (time and place), registration (immediate repetition of three words), attention and calculation (serial sevens, or spelling 'WORLD' backwards), recall (the same three words after a delay), language (naming, repetition, a three-stage command, reading, writing) and a copying task using two overlapping pentagons. It does NOT include a clock-drawing task: a detail the exam frequently tests directly, since it is a common point of confusion with other batteries.
The MoCA is also scored out of 30 but samples executive function and attention more heavily than the MMSE, and includes clock drawing; it is more sensitive than the MMSE for detecting mild cognitive impairment, partly because the MMSE has a well-known ceiling effect (many patients with genuine early impairment still score near the top).
The ACE-III is longer, scored out of 100, and gives a domain-by-domain profile across attention, memory, verbal fluency, language and visuospatial function, rather than a single combined score: useful when a clinician needs to know exactly which domain is driving an overall low score, not just that the score is low.
The Frontal Assessment Battery targets executive function specifically (abstraction, mental flexibility, motor programming, response inhibition), complementing the memory-weighted focus of the MMSE, and is useful when frontal or executive impairment is suspected but the MMSE looks reassuringly normal.
A 30-point test with orientation, registration, serial sevens, recall, language and pentagon copying but NO clock drawing is specifically the MMSE, not the ACE-III or MoCA: a stem describing exactly this combination is testing recall of that one missing element. The MoCA is discriminated from the MMSE by its greater to mild impairment and its inclusion of clock drawing. The ACE-III is discriminated by its length (100 points, five domains) rather than a single overall score. Mild cognitive impairment is discriminated from dementia by whether activities of daily living remain preserved: impaired cognition with preserved daily functioning is MCI; impaired cognition WITH impaired daily functioning is dementia.
No single cutoff score diagnoses dementia on its own; NICE guidance recommends structured cognitive testing as one part of a fuller assessment that also includes collateral history from someone who knows the patient well, blood screening to exclude reversible causes, and imaging where indicated. A normal MMSE does not rule out mild cognitive impairment: a more sensitive test such as the MoCA or ACE-III may still be needed if clinical suspicion remains, since the MMSE's known insensitivity to milder deficits is a recognised limitation, not an oversight.
A confirmed diagnosis of dementia versus MCI changes both urgency and treatment: dementia typically prompts consideration of a cholinesterase inhibitor (such as donepezil) as first-line pharmacological management under NICE guidance, alongside safeguarding, and driving considerations, while MCI is generally managed with monitoring, risk-factor modification, and safety-netting rather than immediate medication. The specific domain profile from ACE-III or detailed neuropsychological testing also shapes which type of dementia is suspected and therefore which management pathway is followed.
When a vignette describes a test's exact components rather than naming it, work out the identity of the test from what it includes and excludes: a missing clock-drawing task, or a score out of 100 rather than 30, is usually the deliberate clue.
Each cognitive test samples specific domains through a specific, recognisable structure: knowing what each test does and doesn't include, and whether daily function is preserved, is what turns a raw score into a diagnosis.