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glabella reflex (i.e. continuous blinking reaction elicited by repetitive light tapping of the glabella with no habituation), and grasp reflex (i.e. handclasp in response to distal ascending pressure on the palm). The presence of primitive reflexes does not reflect specific neuropathological modifications and does not predict the trajectory of future decline (e.g. in cognition) over time.⁵¹

      Posture, gait, and balance

      These functions should be carefully assessed, as they strongly influence the individual’s risk of falls and loss of independence. Various gait parameters can change in the older person due to multifactorial declines in different domains (e.g. sensory loss, motor impairment, cardiorespiratory insufficiency, cognitive deficit, and affective disturbances).⁵² Walking speed is frequently reduced, stride length tends to decrease, and difficulty emerges in navigating inclines and declines.⁴¹ The tandem ability is often reduced, and the need for prolonged double‐limb support time and a slight widening of the base of support is commonly observed.⁵³ Postural changes mostly consist of a slightly stooping of the trunk. Various functional performance tests (e.g. the Short Physical Performance Battery ⁵⁴), easy to use in daily practice in a hospital setting, can support the identification of gait and balance disorders and the implementation of interventions to reduce the risk of falling. Future research efforts based on wearable motion sensor technologies equipped with gyroscopes and accelerometers would help assess the risk of falling during activities of daily life in patients’ real home environment.⁵⁵

      Extrapyramidal signs

      A mild increase in muscle tone, usually associated with a concomitant decrease of muscle bulk and strength, is reported with ageing. In this regard, it should be noticed that mild extrapyramidal signs such as axial bradykinesia, rigidity, resting tremor, and postural instability are common amongst community‐dwelling older individuals even if they do not configure a definite PD.⁵⁶ To achieve the diagnosis of PD, specific criteria have to be satisfied.⁵⁷ The diagnosis of PD is based on a three‐step process. First, parkinsonism is defined by the presence of bradykinesia (e.g. slowness of movement) in combination with tremor and/or rigidity. If the criteria are not met (step 1), prodromal or non‐clinical parkinsonism could be considered (in addition to other non‐parkinsonian tremulous conditions, such as essential or dystonic tremor). Once parkinsonism is diagnosed, it should be determined whether this condition is attributable to idiopathic PD: when absolute exclusion criteria (e.g. brain lesions, drug‐induced parkinsonism, etc.) (step 2) are absent and supportive clinical features (e.g. olfactory loss, sleep disturbances, and other non‐motor symptoms) are present (step 3).⁵⁸ Hence, the presence of isolated tremor, rigidity, or simple slowness of movement is not sufficient to configure the diagnosis of PD per se. More importantly, senile tremor constitutes one of the commonest movement disorders, reaching a prevalence of ~10% in subjects by age 90.⁵⁹ This so‐called ageing‐related tremor emerges in midlife and increases with ageing. The exact nature of this tremor remains unclear, configuring a wide spectrum of disorders that encompasses essential tremor (e.g. idiopathic), dystonic tremor (e.g. tremor associated with dystonia in any body region), and also PD, being associated both with increasing cognitive impairment and mortality.⁵⁸

Cognitive changes with ageing

Declines in an individual’s cognitive functioning are generally considered unavoidable with ageing. Nevertheless, age‐related cognition changes are not uniform, and extreme heterogeneity in cognitive performance is observed among older people. In fact, some older adults retain excellent cognitive performance, sometimes outperforming younger subjects. Others, although within the range of normalcy, show early signs of decline.⁶⁰ Such inter‐individual variability is likely attributable to a wide range of factors, including biological, psychological, health‐related, environmental, and lifestyle determinants, and is probably related to varying activation of compensatory mechanisms.⁶⁰ Multiple sociodemographic variables such as education and lifestyle parameters, including physical and social activity and dietary/nutritional habits, can influence cognition.^61,62 Various chronic conditions such as diabetes, hypertension, vascular disorders, and depression can contribute to cognitive decline, and their prevention and management are essential to cognitively healthy ageing.^63,64 Accordingly, diabetes, midlife hypertension, midlife obesity, physical inactivity, depression, smoking, and low educational attainment have emerged as the main modifiable risk factors for dementia, accounting for around one‐third of AD and vascular dementia cases worldwide.^65,66 There is also recent evidence that performance on neuropsychological tests can be affected by the individual’s frailty status, which is a composite of health and biological deficits accumulated by the organism.⁶⁷ Based on this premise, a proper assessment of cognitive functioning in older people requires approaches and models that comprehensively reflect the biological and clinical complexity of the individual.⁶⁸

Table 6.3 Age‐related changes in attention and memory functions.

      Source: Adapted from Glisky⁶⁰; Zanto and Gazzaley⁷².

Function	Description	Most common age‐related change
Attention
Selective attention	Ability to attend to some stimuli while disregarding others that are irrelevant to a given task	Relevant heterogeneity
Sustained attention	Maintaining vigilance or concentration on a task over time	Relevant heterogeneity
Divided attention Attention switching	Processing two or more sources of information or performing multiple tasks at the same time	Impaired
Working memory	Cognitive system that enables temporary storage and manipulation of information	Impaired
Long‐term memory
Episodic memory	Memory for personally experienced events that occurred at a particular time and place	Impaired
Semantic memory	Memory of general knowledge about the world and words and concepts	Preserved
Autobiographical memory	Memory for one’s personal past (includes both semantic and episodic memories)	Preserved
Procedural memory	Knowledge of skills and procedures that are expressed automatically in performance	Preserved
Implicit memory	Change in behaviour occurring after a prior experience (not consciously or explicitly recalled)	Preserved
Prospective memory	Remembering to perform a planned action at some future point in time	Preserved (frequently with external aids)

Moreover, the ageing process influences certain cognitive functions disproportionately, and

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