The Association Between Neurocognitive Disorders and Gustatory Dysfunction: A Systematic Review and Meta-Analysis

Abstract

Olfactory and gustatory dysfunction have been reported in mild and major neurocognitive disorders (NCDs), with variable results. While olfactory dysfunction has been consistently explored, reports on gustatory alterations are limited. We systematically reviewed case-control studies evaluating gustatory function in NCDs with various etiologies and different neuropathology. Eighteen studies were included in the systematic review, and eight were included in the meta-analysis. Most studies were on Alzheimer’s disease (AD) and Parkinson’s disease (PD). Pooled analyses showed worse global taste threshold and identification (sour in particular) scores in AD than controls and worse global, sweet, and sour scores in AD compared to mild cognitive impairment (MCI). PD with MCI showed worse global, sweet, salty, and sour scores than controls and cognitively unimpaired PD. Taste dysfunction was differentially associated with the severity of cognitive deficits. Gustatory dysfunction may represent a potential cross-disease chemosensory biomarker of NCD. Whether gustatory alterations may be a pre-clinical biomarker of NCD requires further studies.

Association of gustatory dysfunction and Alzheimer's disease: a systematic review and meta-analysis

“…Alzheimer's disease (AD) is the most frequent type of dementia, accounting for 70% of dementia cases (5) . Neurodegenerative symptoms such as episodic memory loss, progressive loss of autonomy in the usual activities, and chemosensory dysfunction have been demonstrated to be symptoms of AD (5)(6)(7) . Olfactory dysfunction is associated with memory and cognitive dysfunction and is known to be early symptom of AD (8) .…”