Association between olfactory loss and cognitive deficits in Parkinson's disease.

OBJECTIVE: The aim of this study was to compare the cognitive deficits and olfaction in PD patients.

PATIENTS AND METHODS: In all, 42 PD patients and 38 controls were selected. All the individuals in both groups underwent cognitive assessment with the SCOPA-Cog neuropsychological battery and Mini-Mental State Examination (MMSE) and olfactory assessment with the Sniffin' Sticks Screening 12 Test. Parkinson's disease dementia (PDD) was diagnosed using the International Parkinson and Movement Disorder Society (MDS) criteria.

RESULTS: The prevalence of olfactory dysfunction in PD patients was 95.24% (40/42). There was no statistically significant difference in olfaction when compared to patients with PDD and PD without cognitive deficits (5.12 ± 3.25 vs. 6.71 ± 2.63, p = 0.115). Attention [r = 0.35, 95% CI = (0.05-0.59), p =  0.01] was the only cognitive domain correlated with olfactory loss in PD patients. There was a higher correlation among the scores of cognitive and olfactory assessments in controls, r=0.40 (95% CI = [0.09-0.64], p = 0.007), with MMSE.

CONCLUSION: The olfactory deficits prevalence in PD patients was significantly high. There may be a correlation between frontal lobe dysfunction and olfactory deficit.