Episodic memory and the medial temporal lobe: not all it seems. Evidence from the temporal variants of frontotemporal dementia
- C Machiel Pleizier1,
- Annelies E van der Vlies2,
- Esther Koedam2,
- Teddy Koene3,
- F Barkhof4,
- Wiesje M van der Flier2,5,
- Philip Scheltens2,
- Yolande Pijnenburg2
- 1Department of Neurology, Diakonessenhuis, Utrecht, the Netherlands
- 2Department of Neurology, Alzheimer Center, VU University Medical Center, Amsterdam, the Netherlands
- 3Department of Medical Psychology, VU University Medical Center, Amsterdam, the Netherlands
- 4Department of Neuroradiology, VU University Medical Center, Amsterdam, the Netherlands
- 5Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, the Netherlands
- Correspondence to C Machiel Pleizier, Department of Neurology, Diakonessenhuis, PO Box 80250, 3508 TG, Utrecht, The Netherlands;
Contributors CMP and YP were responsible for the study concept, design, analysis and interpretation of data, wrote the article and did final revisions of the manuscript. AEvdV was involved in data management, analysis and interpretation of data. EK and PS were involved in the collection of clinical data. TK interpreted the neuropsychological data. FB was responsible for the collection of radiological data (MTA rating). WMvdF was involved in study design and interpretation of data. All authors were involved in editing the manuscript and approved the final version of the submitted article.
- Received 4 February 2012
- Revised 20 July 2012
- Accepted 1 August 2012
- Published Online First 29 August 2012
Background Disproportionate medial temporal lobe atrophy (MTA) is an early finding in Alzheimer's disease (AD). Episodic memory impairment in AD is associated with the degree of MTA. Episodic memory impairment and MTA are also found in semantic dementia (SD) and in right temporal lobe atrophy (RTLA), the temporal variants of frontotemporal dementia, but their relationship is unclear.
Objective To compare episodic memory impairment among patients with these temporal variants of frontotemporal dementia with that of patients with AD with the same degree of MTA.
Methods Episodic memory was tested with the visual association test, and semantic memory (SM) with animal fluency and the visual association naming test. MTA was measured using a visual rating scale. Each patient with SD or RTLA was matched for MTA with two patients with AD. Comparisons of episodic memory and SM were made for patients with SD versus matched patients with AD; patients with RTLA versus matched patients with AD and for SD, RTLA and all patients with AD.
Results 27 patients with SD and 11 with RTLA were matched with 54 and 22 patients with AD, respectively. Episodic memory was less impaired in patients with SD than in those with AD (8 versus 2; p<0.001) and in patients with RTLA than in those with AD (10 versus 4.5; p=0.009). Semantic memory was more affected in patients with SD than in those with AD, and the Mini Mental State Examination score was higher in patients with RTLA than in those with AD. Comparison of the three diagnostic groups showed that episodic memory was most impaired in AD, whereas SM was most impaired in SD.
Conclusion Since episodic memory impairment is more severe in AD than in SD and RTLA, despite a comparable degree of MTA, atrophy of the medial temporal lobe alone cannot account for episodic memory dysfunction.
- Semantic dementia
- frontotemporal dementia
- Alzheimer's disease
- episodic memory
- medial temporal lobe atrophy
- functional imaging
- multiple sclerosis
- CSF dynamics
- Creutzfeldt–Jakob disease
- frontal lobe
Funding The Alzheimer's Center VUmc is supported by Alzheimer's Nederland and Stichting VUmc fonds. The clinical database structure was developed with funding from Stichting Dioraphte.
Competing interests None.
Ethics approval The study was approved by the ethical review board of VU University Medical Center.
Provenance and peer review Not commissioned; externally peer reviewed.