It has long been recognized that frail, older people with multiple chronic illnesses experience higher rates of falls than active, healthy older people. This suggests that, rather than being a non-specific accompaniment of ageing, many falls occur as a result of clinically identifiable causes. Thus, differentiating the relative contribution of pre-existing disease to the risk of falling is an important component of a falls prevention programme, as it enables clinicians involved in the management of older people to identify high risk individuals who may benefit from targeted intervention.

As discussed in Chapter 4, maintenance of the upright posture is a complex task involving many physiological systems. Sensory input from visual and vestibular pathways, muscle spindles, and joint proprioceptors is channelled centrally to the brain where it is rapidly processed to produce appropriate and coordinated motor responses. The key components of this process are represented in Figure 6.1, whilst Table 6.1 lists diseases which can impact on this system to increase an individual's risk of falling.

Many diseases increase the risk of falling by impacting directly on physiological systems, i.e. cataract formation leads to impaired visual acuity and contrast sensitivity. Other intermittent pathologies are less simple to classify. Despite knowledge that treatment leads to a reduction in falls, some conditions have not been (and are never likely to be) studied in such a way as to provide evidence of being an independent predictor of falls, e.g.