Olfactory function in Parkinson's Disease - effects of training

Hard to explain physiologically/pathologically in PD (does this mean that olfaction improves or there is compensation??)...but may have importance and relevance to those of us performing serial smell tests as part of PD risk stratification...incidentally others have talked about olfactory trainin in the past (http://www.fifthsense.org.uk/support/smell-training/ & 

http://onlinelibrary.wiley.com/doi/10.1002/lary.20101/abstract)

Acta Neurol Scand. 2015 Apr 6. doi: 10.1111/ane.12406. [Epub ahead of print]

Knudsen K, Flensborg Damholdt M, Mouridsen K, Borghammer P.

BACKGROUND:

Up to 90% of patients with Parkinson's disease (PD) exhibit olfactory dysfunction, but little is known about the effects of olfactory training. The study aim was to investigate whether the ability to identify olfactory stimuli can be improved by means of a brief training session. Furthermore, the impact of hyposmia on quality of life in PD was investigated by means of a questionnaire.

METHODS:

Olfactory function was rated in 34 patients with PD and in 26 controls before and after a training session. An additional 20 patients with PD served as a control group and were tested twice without an intervening training session. Long-term effects were evaluated in a small subset of patients. Cognitive tests and DaT SPECT scans were performed.

RESULTS:

We demonstrated significant same-day and long-term training effects in trained PD patients compared with non-trained PD patients. A slightly significant correlation was seen between the training effect and DaT putamen values, but not with cognitive test scores. Furthermore, patients with PD reported that hyposmia significantly decreased their quality of life.

CONCLUSIONS:

Patients with PD improved the number of correctly identified odors in an olfactory test through a brief training session. Olfactory training may have potential in rehabilitation of patients with PD.