Impact of the severity of dementia due to Alzheimer's disease on the gustatory sensitivity of older persons

Objective To evaluate the association between the severity of dementia and taste recognition abilities in older persons with Alzheimer's disease (AD). Methods Anthropometric measurements were performed and body mass index was used to determine the nutritional status. The taste strips were used to test gustatory functions of the five basic tastes (sweet, salty, sour, bitter and umami). Results A total of 30 healthy younger subjects, 30 healthy older subjects, 37 with mild stage AD and 23 with moderate stage AD were recruited. The older subjects with moderate AD showed a significant reduction of taste, less recognition of bitter and salty taste (score: 10.6 +/- 2.6; 2.6 +/- 0.9; 1.7 +/- 1.5) when compared to older people without cognitive impairment (score: 13.3 +/- 1.8; 3.4 +/- 0.9; 3.2 +/- 0.9), and less recognition of sweet taste (score: 2.9 +/- 1.2) when compared to subjects with mild stage AD (score: 3.6 +/- 0.8). Impaired recognition of salty taste was detected since the early stages of AD. Among the factors that possibly influence gustatory function, a significant correlation was detected between taste ability and age, medication intake, mini-mental state examination and the nutritional status. Conclusion The severity of dementia is directly associated with greater impairment of taste sensitivity, especially among older subjects with moderate stage disease.