A Quantitative Meta-analysis of Olfactory Dysfunction in Epilepsy

  • Kiran Khurshid
  • Andrew J. D. Crow
  • Petra E. Rupert
  • Nancy L. Minniti
  • Melissa A. Carswell
  • Dawn J. Mechanic-Hamilton
  • Vidyulata Kamath
  • Richard L. Doty
  • Paul J. Moberg
  • David R. RoalfEmail author


Olfactory dysfunction in epilepsy is well-documented in several olfactory domains. However, the clinical specificity of these deficits remains unknown. The aim of this systematic meta-analysis was to determine which domains of olfactory ability were most impaired in individuals with epilepsy, and to assess moderating factors affecting olfactory ability. Extant peer-reviewed literature on olfaction in epilepsy were identified via a computerized literature search using PubMed, MEDLINE, PsycInfo, and Google Scholar databases. Twenty-one articles met inclusion criteria. These studies included a total of 912 patients with epilepsy and 794 healthy comparison subjects. Included studies measured olfaction using tests of odor identification, discrimination, memory, and detection threshold in patients with different types of epilepsy, including temporal lobe epilepsy (TLE), mixed frontal epilepsy (M-F), and mixed epilepsy (MIX). Olfactory deficits were robust in patients with epilepsy when compared to healthy individuals, with effect sizes in the moderate to large range for several olfactory domains, including odor identification (d = −1.59), memory (d = −1.10), discrimination (d = −1.04), and detection threshold (d = −0.58). Olfactory deficits were most prominent in patients with TLE and M-F epilepsy. Amongst patients with epilepsy, sex, age, smoking status, education, handedness, and age of illness onset were significantly related to olfactory performance. Overall, these meta-analytic findings indicate that the olfactory system is compromised in epilepsy and suggest that detailed neurobiological investigations of the olfactory system may provide further insight into this disorder.


Olfaction Smell Epilepsy Seizures Seizure disorder 


Funding Sources

This work was supported by K01 MH102609 (Roalf), the Brain and Behavior Foundation NARSAD Young Investigator grant program (Roalf), and the John Hopkins Clinical Research Scholars Program KL2TR001077 (Kamath).

Role of the Funding Sources

The funding sources had no role in the design, collection, analysis or manuscript preparation for this study.

Compliance with Ethical Standards

Ethical Publication Statement

We affirm that we have read the Neuropsychology Review’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.

Conflicts of Interest Disclosures

The authors declare that they have no conflict of interest.

Supplementary material

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ESM 1 (XLSX 31 kb)
11065_2019_9406_MOESM2_ESM.doc (64 kb)
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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  • Kiran Khurshid
    • 1
  • Andrew J. D. Crow
    • 2
  • Petra E. Rupert
    • 3
  • Nancy L. Minniti
    • 4
  • Melissa A. Carswell
    • 5
  • Dawn J. Mechanic-Hamilton
    • 6
  • Vidyulata Kamath
    • 7
  • Richard L. Doty
    • 8
  • Paul J. Moberg
    • 2
    • 6
    • 8
  • David R. Roalf
    • 2
    Email author
  1. 1.Department of NeurologyIndiana University School of MedicineIndianapolisUSA
  2. 2.Department of PsychiatryUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaUSA
  3. 3.Department of PsychologyUniversity of PittsburghPittsburghUSA
  4. 4.Department of Physical Medicine and RehabilitationTemple University HospitalPhiladelphiaUSA
  5. 5.The Neurology CenterRockvilleUSA
  6. 6.Department of NeurologyUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaUSA
  7. 7.Department of Psychiatry and Behavioral SciencesJohns Hopkins School of MedicineBaltimoreUSA
  8. 8.Smell & Taste Center, Department of Otorhinolaryngology: Head & Neck SurgeryUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaUSA

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