Vision: Research has found that changes in visual function, such as reduced contrast sensitivity, impaired depth perception, and decreased visual acuity, are associated with an increased risk of dementia. Studies have also found that people with Alzheimer’s disease and other forms of dementia often have vision problems, such as difficulty recognizing faces or reading.
Hearing: Hearing loss is a common age-related condition, and studies have shown that it may be a risk factor for dementia. In a large study of older adults, those with hearing loss had a higher risk of cognitive decline and dementia than those with normal hearing.
Smell: The sense of smell can also decline with age, and research suggests that this decline may be associated with dementia. In one study, older adults with a poor sense of smell were more likely to develop dementia over a five-year period than those with a better sense of smell.
Touch: Changes in the sense of touch can also occur with age, and some research has suggested that these changes may be related to cognitive decline. For example, one study found that older adults with reduced tactile sensitivity had a higher risk of cognitive impairment.
In general, changes in sensory function can be an important indicator of brain health and may be an early sign of cognitive decline or dementia. Regular monitoring of sensory function, along with other cognitive assessments, can help identify individuals who may be at risk for dementia and allow for earlier interventions to improve outcomes.
Chinese 
English