OLFACTION AS A DIFFERENTIATING TOOL IN IPD‚ FIRST DEGREE RELATIVES OF FAMILIAL PD AND PARKINSONISM
Authors: Abhishek Pathak‚ Jeen Mathew‚ Vinay Goyal‚ Garima Shukla1‚ Madhuri Behari*
Olfactory dysfunction is considered a marker of synucleopathies and is reported in patients of Parkinson Disease (PD)‚ multiple system atrophy (MSA) and Dementia with Lewy bodies (LBD) several years before motor symptoms make their appearance. It therefore‚ can be used as a biomarker to detect these ailments before motor symptoms make their appearance in the absence of more expensive tests. We undertook this case control study to investigate olfactory function in PD‚ Parkinsonism plus syndromes [PPS i.e. MSA and Progressive Supranuclear Palsy (PSP)]‚ familial PD and first-degree relatives of familial PD patients and compared the results with age and gender matched healthy controls. Consecutive 197 PD patients‚ 26 familial PD (FPD) patients‚ 2’ first degree relatives of familial PD patients (RPD)‚ 58 patients of Parkinsonism plus syndrome (PPS) including 38 MSA and 20 PSP patients and 200 age and gender matched healthy controls were included in the study from movement disorder clinic of a tertiary care teaching hospital in India. Clinical details were recorded on a pre-tested format. All the subjects underwent a formal olfactory assessment with validated Indian Smell Identification Test battery (INSIT) and commercially available Sniffin stics Test® (SST). There was significant difference in smell scores between PD patients familial PD (FPD) patients and PPS patients on one hand and and healthy controls n the other (all p<0.0001) on both Indian smell Identification Test (INSIT) battery and SST. Both INSIT and SST showed similar results when tested on PD‚ PPS‚ FPD‚ RPD and healthy controls‚ showing an agreement of 8’% between the two tests. Statistically significant difference between MSA and PSP and healthy controls were observed; but not between MSA and PD and between RPD and age matched healthy control. ROC curve showed sensitivity of 0.814 and specificity of 0.68 for INSIT at cut off score of 7 and of 6 on INSIT and SST respectively. The study confirms that INSIT‚ the indigenously prepared inexpensive Indian smell identification test using odorants‚ which are familiar to Indian population‚ is non-inferior to the SST and that there is a good agreement between the two. Olfactory dysfunction exists in PD‚ Parkinsonism plus syndromes patients‚ especially so in MSA and FPD patients in comparison to healthy controls. There was significant difference in the smell scores between MSA and PSP patients. We did not find significant difference between the smell scores of first-degree relatives of familial PD and healthy control.
KEY WORDS: Parkinson disease‚ Olfaction‚ Familial PD‚ Parkinsonism‚ First degree relatives