Design for dementia builds on design that is beneficial for older people in general. This section provides a brief summary of the impairments of old age for which design can help.
Designing effectively for people with dementia involves first appreciating that they are mainly older, indeed often very old people, who are likely to have the same impairments as their contemporaries. These impairments will often affect their sight, hearing and mobility. The difference is that they may not be aware that they have them.
The prevalence of blindness and visual impairment increases exponentially with age (World Blind Union, 2011). Older people’s eyes are likely to have thick- ened lenses, which will impair their ability to see colour, make glare harder to tolerate and slow their ability to adjust to different light levels. Cataracts may affect their ability to see – and because of their dementia these may go unreported and untreated. They may have macular degeneration, resulting in loss of detailed vision. This has implications for reading, watching TV, eating, identifying hazards and recognising faces. Some people will have glaucoma, which affects peripheral vision, impacting mobility and making it harder to detect hazards. Dementia itself is likely to adversely affect the parts of the brain used to construct the visual scene.
People with sight impairment and dementia need a lot of light, combined with contrasting tones (rather than colour itself ) to ensure objects are visible.
Over 70% of people aged over 70 have a hearing impairment (Action on Hearing Loss, 2011). There are two main forms of impairment. Conductive loss occurs when sound is not conducted efficiently through the outer ear canal to the eardrum and the ossicles of the middle ear. Sensorineural loss is caused by damage to the inner ear or the nerve pathways to the brain. Presbycusis is a form of gradual, age-related sensorineural hearing loss.
Older people commonly experience a combination of both conductive and sensorineural hearing loss. As well as a general deterioration in their ability to hear, both types of impairment lead to specific difficulties. These include reduced ability to hear high frequency sound; an oversensitivity to low fre- quency sound; and an impaired ability to filter out unwanted sound. The need to wear hearing aids can further impacts on the hearing difficulties of many older people. For example, if batteries are not replaced or the tubes become obstructed by wax, hearing aids may become a hindrance to hearing. The result can be a real struggle to remain calm, concentrate and have a normal conversation with others.
A person with dementia may also have tinnitus, which is a perception of sound where there is none externally. Vestibular disorders of the ear (e.g. Ménière’s disease) can lead to imbalance, dizziness and hearing changes.
People with hearing impairment and dementia need a quiet environment with extra attention paid to acoustics. Measures should be taken to avoid or prevent sources of noise, and to provide sound absorption.
Circadian rhythm (body clock)
Many older people have difficulty regulating their body clock, and this is especially common for those with dementia. They can sleep a lot during the day and be awake at night. Television and computer use at night can also add to this problem due to emission of ‘blue’ light (Giuliano, 2012). For many people, problems with their body clock can be remedied by exposure to high levels of light in the morning. Daylight (or an equivalent light with high blue content), combined with dark and quiet conditions at night, is extremely useful. Clocks can be a helpful starting point for some people who have become disorientated in terms of time (see section 6).
The majority of older people have some problems relating to their muscles and joints. They may stoop; experience pain; have impaired reach and grip; find it hard to balance; or experience general mobility problems. Vitamin D is essential for good bone and muscle health, and the best and cheapest way to get it is to expose skin (e.g. arms and legs) to sunlight for around ten minutes a day between April and September (avoiding exposure to midday sun). This underlines the importance of easy access to an outside space.
The Dementia Services Development Centre Iris Murdoch Building (2013).
University of Stirling, Stirling