There is a high prevalence of olfactory deficits in patients with Parkinson disease (PD) and these deficits may be correlated with frontal lobe dysfunction, according to study results published in Clinical Neurology and Neurosurgery.
The study included 42 patients with PD and 38 controls. All participants underwent cognitive assessment with the SCOPA-Cog neuropsychological battery and Mini-Mental State Examination (MMSE). Participants underwent olfactory assessment via the Sniffin’ Sticks Screening 12 Test. The researchers used the International Parkinson and Movement Disorder Society (MDS) criteria to diagnose PD dementia.
Participants with PD had lower scores on both the cognitive and olfactory assessments compared with controls.
In participants with PD, 40 of 42 (95.24%) had olfactory dysfunction. Using the MDS criteria, 34 participants (81%) with PD were diagnosed with PD dementia.
The researchers did not find a significant difference in olfaction between participants with PD dementia (5.12±3.25) and patients with PD without cognitive deficits (6.71±2.63; P =.115). The only cognitive domain associated with olfactory loss in participants with PD was attention [r=0.35; 95% CI, 0.05-0.59; P =.01].
“There may be only a correlation between frontal lobe dysfunction and olfaction deficit. However, the results were insufficient to establish a correlation between an evolution of the olfactory deficit and the [PD dementia] onset,” the researchers wrote. “Future studies with a larger number of patients, and at several stages of the disease, may bring new insights into this issue.”
Camargo CHF, Jobbins VA, Serpa RA, et al. Association between olfactory loss and cognitive deficits in Parkinson’s disease. Clin Neurol Neurosur. 2018;173:120-123.