Olfactory function in people with genetic risk of dementia

Background: Screening for sensorial impairment is a secondary objective in the context of neurodegenerative diseases, including dementias. For example, olfactory dysfunction is among the first signs of Alzheimer's disease. There has been no study of olfactory function in Irish subjects at risk of dementia. Aim: To investigate olfactory function in non-demented Irish persons, who carry genetic risk factors for dementia. Methods: Thirty-eight Irish adult subjects, who are at risk of dementia, were recruited. Cognitive performance and olfactory function were assessed and apolipoprotein E (APOE) genotype determined. Results: Three and six subjects had a Mini Mental State Examination (MMSE) and Brief Smell Identification Test (B-SIT) score, respectively, outside the normal range. While five out of the fifteen ε-4 allele positive subjects had B-SIT scores outside the normal range, only one out of the twenty-three ε-4 allele negative subjects had; the difference in this frequency was significant (P=0.025). There was no significant difference (P=0.266) in the frequency of abnormal MMSE scores between ε-4 allele groups. Conclusion: Further investigation is required to explore the reasons for the higher prevalence of olfactory dysfunction in ε-4 allele positive subjects.