Verbal memory is associated with structural hippocampal changes in newly diagnosed Parkinson's disease
- Mona K Beyer1,2,
- Kolbjorn S Bronnick1,
- Kristy S Hwang3,4,
- Niels Bergsland5,
- Ole Bjorn Tysnes5,6,
- Jan Petter Larsen1,
- Paul M Thompson3,4,
- Johanne H Somme7,
- Liana G Apostolova3,4
- 1Norwegian Centre for Movement Disorders, Stavanger University Hospital, Stavanger, Norway
- 2Department of Radiology and Nuclear Medicine–Rikshospitalet, Oslo University Hospital, Oslo, Norway
- 3Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
- 4Laboratory of Neuro Imaging, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
- 5Buffalo Neuroimaging Analysis Center, University at Buffalo, Buffalo, New York, USA
- 6Department of Neurology, Haukeland University Hospital, Bergen, Norway
- 7Department of Neurology, Cruces University Hospital, Baracaldo, Spain
- Correspondence to Dr Mona Kristiansen Beyer, Division for Diagnostics and Intervention–Rikshospitalet, Oslo University Hospital, Sognsvannsveien 20, Oslo 02770, Norway;
- Received 1 May 2012
- Revised 25 August 2012
- Accepted 28 August 2012
- Published Online First 15 November 2012
Background and objective Cognitive impairment, including impairment of episodic memory, is frequently found in newly diagnosed Parkinson's disease (PD). In this longitudinal observational study we investigated whether performance in memory encoding, retention, recognition and free recall is associated with reduced hippocampal radial distance.
Methods We analysed baseline T1-weighted brain MRI data from 114 PD subjects without cognitive impairment, 29 PD subjects with mild cognitive impairment and 99 normal controls from the ParkWest study. Age- and education-predicted scores for the California Verbal Learning Test 2 (CVLT-2) and tests of executive function were regressed against hippocampal radial distance while adjusting for imaging centre.
Results There was no association between encoding or performance on executive tests and hippocampal atrophy in the PD group. In the full PD sample we found bilaterally significant associations between lower delayed free recall scores and hippocampal atrophy in the CA1, CA3 and subiculum area (left, p=0.0013; right, p=0.0082). CVLT-2 short delay free recall scores were associated with bilateral hippocampal CA1 and subicular atrophy in the full PD sample (left, p=0.013; right, p=0.047). CVLT-2 recognition scores showed a significant association with right-sided subicular and CA1 atrophy in the full PD sample (p=0.043).
Conclusions At the time of PD diagnosis, subjects’ verbal memory performance in recall and recognition are associated with atrophy of the hippocampus, while encoding is not associated with hippocampal radial distance. We postulate that impaired recall and recognition might reflect deficient memory consolidation at least partly due to structural hippocampal changes.