Cognitive ageing: a primer

• A. A sudden decline in memory that occurs at the same time for all adults over 65
• B. The gradual changes in cognitive abilities such as memory, processing speed, and attention that occur across the adult lifespan ✓
• C. The development of dementia as a normal and unavoidable part of growing older
• D. Changes in intelligence that only affect people who have a family history of neurological disease

Why: Cognitive ageing refers to the gradual, lifelong changes in cognitive functions such as memory, processing speed, and attention. It is not a sudden event, and it is distinct from dementia, which is a disease process rather than a normal part of ageing.

• A. Vocabulary knowledge
• B. General knowledge accumulated over a lifetime
• C. Processing speed ✓
• D. Knowledge of well-learned facts about the world

Why: Processing speed, meaning how quickly a person can perceive and respond to information, shows some of the most consistent declines across adulthood. Crystallised abilities such as vocabulary and general knowledge often remain stable or even increase with age.

• A. Fluid intelligence is measured in adults only, while crystallised intelligence is measured in children
• B. Fluid intelligence involves novel problem-solving and reasoning, which tends to decline with age, while crystallised intelligence relies on accumulated knowledge, which tends to be maintained ✓
• C. Fluid intelligence improves with age, while crystallised intelligence declines sharply after age 40
• D. Fluid intelligence refers to emotional reasoning, while crystallised intelligence refers to mathematical reasoning

Why: Raymond Cattell's distinction holds that fluid intelligence supports novel reasoning and is more dependent on neural speed and working memory, so it tends to decline in later life. Crystallised intelligence reflects stored knowledge and skills, which usually remain stable or grow with age.

• A. A complete loss of the ability to form new memories
• B. Difficulty retrieving names or specific words, often experienced as a 'tip of the tongue' state ✓
• C. Improved recall of recently learned information compared with younger adults
• D. Loss of all long-term memories formed before the age of 50

Why: Word-finding difficulties and tip-of-the-tongue experiences become more frequent with age, reflecting changes in retrieval efficiency. These are normal changes and do not indicate the complete memory loss seen in severe disease, which is why option A and D are incorrect.

• A. Because normal ageing always leads to dementia within ten years
• B. Because normal ageing usually involves mild, gradual changes that do not stop daily functioning, whereas pathological decline is more severe and progressive and may warrant clinical assessment ✓
• C. Because pathological decline is always reversible with lifestyle changes alone
• D. Because normal ageing affects only physical abilities and never cognitive ones

Why: Normal cognitive ageing typically produces mild changes that people can compensate for and that do not interfere with independence. Pathological decline is more pronounced, progressive, and disruptive to everyday life, and recognising the difference allows timely clinical evaluation.

• A. Episodic memory for recent events
• B. Semantic memory (general world knowledge and vocabulary) ✓
• C. Prospective memory for future intentions
• D. Working memory span for novel digit sequences

Why: Semantic memory and vocabulary knowledge tend to remain stable or even improve with age, while episodic memory and processing speed typically decline.

• A. Source amnesia
• B. Encoding failure
• C. Transient blocking
• D. Tip-of-the-tongue state ✓

Why: The tip-of-the-tongue state describes a retrieval failure in which the target word is partially accessible, and it becomes more frequent with age even when the information is retained.

• A. It increases steadily until late adulthood
• B. It remains constant across the lifespan
• C. It declines gradually beginning in early adulthood ✓
• D. It declines only after age 80

Why: Processing speed is one of the most consistently documented cognitive abilities to decline, with measurable slowing beginning in early adulthood and continuing gradually across the lifespan.

• A. Older adults have lower motivation during recognition tests
• B. Recognition relies more on cues and familiarity, which are less affected by ageing than self-initiated retrieval ✓
• C. Recognition tests are always easier for everyone regardless of age
• D. Older adults encode information more deeply than younger adults

Why: Free recall requires self-generated retrieval strategies and search of memory without external support, which decline with age. Recognition benefits from environmental cues and familiarity signals, which are relatively preserved.

• A. Sustained vigilance and divided attention ✓
• B. Vocabulary-based attention to familiar words
• C. Automatic detection of highly salient stimuli
• D. Recognition of overlearned well-practised skills

Why: Divided attention and sustained attention tasks tend to show age-related decline, whereas overlearned skills and automatic processes are generally well preserved.

• A. The time taken to recall long-term autobiographical memories
• B. The speed at which an individual can perform simple cognitive operations accurately ✓
• C. The rate at which vocabulary is acquired across the lifespan
• D. The ability to learn new motor skills under time pressure

Why: Processing speed refers to how quickly a person can carry out elementary cognitive tasks, such as comparing symbols or matching digits, and it is one of the most consistently documented domains showing age-related decline.

• A. A set of higher-order processes that control and coordinate other cognitive abilities, such as planning, inhibition and working memory updating ✓
• B. The automatic retrieval of overlearned facts such as one's own name
• C. Sensory discrimination of visual and auditory stimuli
• D. The stable store of general knowledge accumulated over a lifetime

Why: Executive functions are top-down control processes that regulate goal-directed behaviour, including inhibition, switching between tasks, and holding and manipulating information in working memory.

• A. Because it is directly measured by the length of a person's education
• B. Because slower basic processing can limit the resources available for more complex tasks, so it helps explain declines in memory and reasoning ✓
• C. Because it increases steadily into the seventies and then plateaus
• D. Because it depends mainly on vocabulary size

Why: Salthouse's processing speed theory proposes that slowing of elementary operations reduces the time available for later stages of processing and can constrain working memory, so statistically controlling for speed often reduces age differences in other measures.

• A. The Digit Symbol Substitution Test ✓
• B. The Boston Naming Test
• C. The Wechsler Vocabulary subtest
• D. The Wisconsin Card Sorting Test

Why: The Digit Symbol Substitution Test, a subtest of the Wechsler scales, requires rapid pairing of symbols with digits and is a widely used, sensitive index of processing speed that typically declines with age.

• A. Working memory capacity under heavy load
• B. Crystallised knowledge and semantic vocabulary ✓
• C. Inhibitory control in the Stroop task
• D. Set-shifting between task rules

Why: Crystallised abilities such as vocabulary and general knowledge tend to remain stable or even improve into later adulthood, whereas speed, working memory and many executive components show age-related decline.

• A. Cerebellum
• B. Hippocampus ✓
• C. Medulla oblongata
• D. Occipital lobe

Why: The hippocampus plays a central role in consolidating new episodic memories. It is one of the regions most affected by age-related volume loss and changes in connectivity, which contributes to memory difficulties in later life.

• A. Myelination
• B. Apoptosis
• C. Neuroplasticity ✓
• D. Synaptic pruning

Why: Neuroplasticity refers to the brain's capacity to change its connections and functional organisation across the lifespan. Myelination and synaptic pruning are specific mechanisms that contribute to plasticity, but the umbrella term is neuroplasticity.

• A. Increase in white matter integrity in all regions
• B. Reduction in myelin integrity and white matter volume ✓
• C. Growth of new neurons throughout the cortex
• D. Increased density of dopamine receptors in the striatum

Why: With ageing, myelin can deteriorate and white matter volume tends to decrease, particularly in frontal regions. This disrupts the speed of signal transmission between regions, contributing to slower processing speed.

• A. Long-term potentiation ✓
• B. Neurogenesis
• C. Gliosis
• D. Excitotoxicity

Why: Long-term potentiation (LTP) is a process in which repeated simultaneous activation of connected neurons strengthens their synapses, providing a cellular basis for learning and memory. It remains functional in older adults, though it may be less efficient.

• A. Prefrontal cortex ✓
• B. Brainstem
• C. Thalamus
• D. Spinal cord

Why: The prefrontal cortex supports executive functions including planning, working memory, and inhibition. It is among the regions showing earlier and more pronounced age-related structural and functional change, which underlies some declines in these abilities.

• A. The brain's ability to store unlimited memories throughout life
• B. The brain's capacity to cope with age-related or pathological damage by using flexible, efficient, or alternative neural networks ✓
• C. The amount of glucose stored in the brain for use during demanding tasks
• D. The number of neurons that remain undamaged after a stroke

Why: Cognitive reserve refers to the brain's resilience, allowing individuals to maintain function despite age-related changes or pathology by drawing on flexible and compensatory neural processes.

• A. Consuming large amounts of caffeine daily
• B. Long-term engagement in mentally stimulating activities such as education, reading, or complex work ✓
• C. Sleeping more than ten hours per night
• D. Avoiding all social contact after retirement

Why: Sustained cognitive engagement through education, occupation, and leisure is repeatedly linked to greater cognitive reserve, though causal interpretation remains debated.

• A. It permanently prevents all neuron loss
• B. It can support blood flow, promote neurogenesis in the hippocampus, and improve cardiovascular health linked to cognition ✓
• C. It has no measurable effect on the brain
• D. It increases the rate of amyloid plaque formation

Why: Aerobic exercise improves cerebral blood flow, supports hippocampal health and neurotrophic factors such as BDNF, and reduces vascular risk factors that affect cognition.

• A. Social interaction removes the need for the brain to store information
• B. Social interaction provides complex cognitive demands, emotional support, and reduces risks such as depression and isolation ✓
• C. Social contact directly eliminates tau proteins
• D. Talking to others increases the size of the skull

Why: Social networks stimulate multiple cognitive processes such as language, memory, and attention, while also buffering stress and depression, which are risk factors for cognitive decline.

• A. Education guarantees that a person will never develop dementia
• B. Higher education is associated with a later onset of symptoms, but it does not necessarily prevent underlying brain pathology ✓
• C. Education increases dementia risk because it strains the brain
• D. Education has no relationship with cognitive ageing outcomes

Why: Epidemiological studies show that more education is linked to delayed clinical symptoms, reflecting greater reserve, but people with high education can still show significant underlying pathology.

• A. Forgetting entire conversations that took place earlier the same day
• B. Occasionally struggling to recall a name but remembering it later ✓
• C. Getting lost in familiar neighbourhoods
• D. Being unable to follow the rules of a familiar card game

Why: Occasional word-finding difficulties and delayed recall of names are common in healthy ageing and the memory is usually retrieved later with cues. Forgetting whole conversations, getting lost in familiar places, and losing the ability to follow familiar routines are more characteristic of dementia.

• A. Remembering how to tie their shoelaces
• B. Recalling recent events and newly learned information ✓
• C. Recognising the faces of family members they have known for decades
• D. Remembering the meaning of common words

Why: Early Alzheimer's typically affects episodic memory for recent events and learning of new information, while long-established procedural skills, long-term semantic knowledge, and well-known relationships are preserved until later stages.

• A. Needing a few extra minutes to process information in a conversation
• B. Becoming less interested in new hobbies over time
• C. Difficulty managing finances or following familiar recipes that were once routine ✓
• D. Making occasional small errors when doing mental arithmetic

Why: Declining ability to perform familiar, complex everyday tasks such as managing finances or following well-known recipes is a functional change that goes beyond normal ageing and warrants clinical assessment. Slower processing speed and minor arithmetic slips are common in healthy older adults.

• A. Forgetting is usually complete and permanent
• B. Information is often retrievable with hints or given time ✓
• C. Memory loss progressively worsens with no stabilisation
• D. Insight into memory problems is typically absent

Why: In normal ageing, memory lapses tend to be partial and information can often be retrieved with cues, time, or reminders. In dementia, forgetting is more persistent, and cues typically do not help. People with normal ageing also usually recognise and worry about their lapses, whereas insight is often reduced in dementia.

• A. Occasionally misplacing keys
• B. Taking longer to learn a new smartphone app
• C. Repeatedly asking the same questions within a short period, with no memory of having asked ✓
• D. Forgetting why you walked into a room

Why: Repeatedly asking the same questions without any memory of previously asking them reflects impaired short-term memory and is a recognised early sign of dementia. Misplacing items, slower learning of new technology, and brief moments of forgetting why you entered a room are all common in healthy ageing.

• A. A steady, rapid decline in all cognitive abilities beginning at age 30
• B. A mix of stable and declining abilities, with crystallised knowledge often maintained while processing speed tends to slow ✓
• C. No measurable change in any cognitive function across adulthood
• D. Complete loss of memory after age 65 in most healthy adults

Why: Normal ageing involves uneven changes: processing speed, working memory and some aspects of episodic memory often decline gradually, while crystallised intelligence (accumulated knowledge and vocabulary) is typically preserved or even improves into later life.

• A. Fluid intelligence is stored knowledge; crystallised intelligence is reasoning on novel problems
• B. Fluid intelligence is reasoning and problem-solving on new material; crystallised intelligence is accumulated knowledge and skills ✓
• C. Fluid intelligence is measured only in children; crystallised intelligence only in adults
• D. Fluid and crystallised intelligence are two names for the same ability

Why: Fluid intelligence refers to the capacity to reason abstractly and solve novel problems, which tends to peak in early adulthood and decline with age. Crystallised intelligence reflects learned knowledge and vocabulary, which is generally maintained across the lifespan.

• A. Consuming large amounts of caffeine daily
• B. Regular physical activity ✓
• C. Avoiding all social contact to reduce stress
• D. Sleeping more than ten hours per night

Why: Regular aerobic and physical activity is consistently associated with better cognitive performance and lower dementia risk in observational and trial evidence. Social engagement is also protective, while excessive sleep and avoiding social contact are not recommended strategies.

• A. The amount of money a person saves for healthcare in old age
• B. The brain's capacity to cope with damage or pathology through flexible, efficient or alternative neural networks ✓
• C. The number of memories a person can store at one time
• D. A measure of how quickly a person can recall recent news

Why: Cognitive reserve describes the brain's resilience, built through education, occupational complexity and mentally stimulating activity. Individuals with higher reserve can sometimes tolerate more neuropathology before showing clinical symptoms.

• A. Hearing loss has no connection to cognition or dementia risk
• B. Untreated hearing loss is associated with faster cognitive decline and higher dementia risk, possibly due to cognitive load and social isolation ✓
• C. Hearing loss improves memory by reducing distractions
• D. Only severe hearing loss in childhood affects later cognition

Why: Epidemiological evidence links midlife and later hearing loss to greater cognitive decline and dementia risk. Proposed mechanisms include increased cognitive load diverting resources from memory, reduced social engagement, and changes in brain stimulation, which is why hearing aids are a recommended intervention.