title: Evidence of neuronal compensation during episodic memory in subjective memory impairment.
abstract: BACKGROUND
  Accumulating evidence suggests that the mere subjective feeling of memory impairment in the absence of objective cognitive deficits may precede mild cognitive impairment in the continuum of Alzheimer disease manifestation. Brain imaging studies have provided insights into structural and functional alterations at the clinical stages of dementia and mild cognitive impairment, but the functional characteristics of subjective memory impairment (SMI) are largely unstudied.
  
  
  OBJECTIVE
  To investigate brain activation during memory tasks in individuals without cognitive impairment who report SMI compared with control subjects without cognitive impairment and without SMI.
  
  
  METHODS
  Functional magnetic resonance imaging study of episodic memory and working memory.
  
  
  METHODS
  Memory outpatient clinic.
  
  
  METHODS
  Nineteen participants reporting SMI without cognitive impairment and 20 control individuals without cognitive impairment and SMI.
  
  
  METHODS
  Brain activation patterns and performance during an associative face-profession episodic memory task, including encoding, recall, and recognition, and a working memory task.
  
  
  RESULTS
  Compared with the control group, SMI was associated with a reduction in right hippocampal activation during episodic memory recall in the absence of performance deficits. This was accompanied by increased activation of the right dorsolateral prefrontal cortex. No differences in performance and no difference in brain activation during working memory were observed in the SMI group.
  
  
  CONCLUSIONS
  These results suggest that SMI is accompanied by functional alterations in hippocampal integrity that reflect early neuronal dysfunction and by compensatory mechanisms that preserve memory performance.
authors.affiliation: Department of Psychiatry and Psychotherapy, Division of Mind and Brain Research, Charité-Universitätsmedizin Berlin, Campus Mitte, Charitéplatz 1, Berlin, Germany. susanne.erk@charite.de
authors.forename: Susanne
authors.initials: S
authors.lastname: Erk
authors.forename: Annika
authors.initials: A
authors.lastname: Spottke
authors.forename: Alice
authors.initials: A
authors.lastname: Meisen
authors.forename: Michael
authors.initials: M
authors.lastname: Wagner
authors.forename: Henrik
authors.initials: H
authors.lastname: Walter
authors.forename: Frank
authors.initials: F
authors.lastname: Jessen
mesh_terms: D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006624:Hippocampus / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008568:Memory / Q000502:physiology; D008569:Memory Disorders / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D011939:Mental Recall / Q000502:physiology*; D017397:Prefrontal Cortex / Q000503:physiopathology; D011597:Psychomotor Performance / Q000502:physiology; D057566:Self Report