Are patients with Parkinson’s disease who have either mild to moderate microsmia, severe microsmia or anosmia clinically different?

Abstract

Introduction: Olfactory loss is a common non-motor symptom of Parkinson’s disease (PD), which has the potential to have a negative effect on quality of life. However, research examining PD patients with varying degrees of loss of sense of smell and whether they are clinically distinct and the implications of the loss of sense of smell when nursing a patient with PD appears to be poorly explained. Objective: To investigate whether patients with PD who have either mild/moderate microsmia, severe microsmia or anosmia (as measured by the University of Pennsylvania Smell Identification Test (UPSIT)) were clinically different when compared across a range of motor, non-motor and quality of life domains. Methodology: This is an open cross-sectional observational study, involving 112 patients (of both genders) who have a diagnosis of PD. Tools and scales used include the motor rating subscales in the Unified Parkinson’s Disease Rating Scale (UPDRS), the Non-motor Symptoms Questionnaire (NMSQ), the PDQ39 Quality of Life Questionnaire (PDQ39), the Hoehn and Yahr scale (H&Y), the Rapid Eye Movement Behaviour Disorder Screening Questionnaire, (RBD) and the Montreal Cognitive Assessment (MoCA). Results: Seventy-two males and forty females have been recruited for this study. Age ranged from 49 - 89 years (mean age 71 years). Eight-five (77%) of the PD patients were at stage 1 or 2 Hoehn and Yahr staging highlighting the study sample mainly consisted of PD patients with minimal or no functional impairment, without impairment of balance. Disease duration ranged from 6 months to 19 years (mean duration 5.5 years). All PD patients (except two) were considered to have either normal cognition or mild cognitive impairment, defined by the MoCA (mean MoCA 26.1). All the PD patients recruited for this study had loss of sense of smell and 91% had -in fact- severe microsmia or anosmia. Seventy-nine (70.5%) PD patients correctly detected a reduced sense of smell. Twenty-nine out of the 33 PD patients (97%) (self-reporting a normal sense of smell) had, in fact, a severe degree of loss of sense of smell (Mean UPSIT 16) without realising it. Overall loss of sense of smell was not correlated with severity or stage of PD, duration of disease, medication, smoking, the environment in which the PD patient was tested, whether they had phantosmia (persistent pleasant or disgusting smell) or taste problems. There was also no correlation between the motor, non-motor, rapid eye movement disorder and quality of life themes during whole group analysis. However, on sub-group analysis, a positive correlation was noted between sense of smell score and PD patients with normal cognition compared to those with mild cognitive impairment using MoCA ( =0.213, p=0.024) and non-motor symptom dribbling of saliva during the day (p=0.003), There was also a negative correlation in PDQ39 cognition theme (score =-0.012 p=0.036), minutes since last PD medication taken ( =-0.2634, p=0.008), timing of levodopa dose ( =-0.1875, p=0.015), and individual domains of the UPDRS motor scores, including posture ( = -.231 p=0.014) facial expression ( =-0.207 p=0.029) and arising from a chair ( =-0.190 p=0.045).