title: Memory deficits in amyotrophic lateral sclerosis are not exclusively caused by executive dysfunction: a comparative neuropsychological study of amnestic mild cognitive impairment.
abstract: BACKGROUND
  Recent work suggests that ALS and frontotemporal dementia can occur together and share at least in part the same underlying pathophysiology. However, it is unclear at present whether memory deficits in ALS stem from a temporal lobe dysfunction, or are rather driven by frontal executive dysfunction. In this study we sought to investigate the nature of memory deficits by analyzing the neuropsychological performance of 40 ALS patients in comparison to 39 amnestic mild cognitive impairment (aMCI) patients and 40 healthy controls (HC). The neuropsychological battery tested for impairment in executive functions, as well as memory and visuo-spatial skills, the results of which were compared across study groups. In addition, we calculated composite scores for memory (learning, recall, recognition) and executive functions (verbal fluency, cognitive flexibility, working memory). We hypothesized that the nature of memory impairment in ALS will be different from those exhibited by aMCI patients.
  
  
  RESULTS
  Patient groups exhibited significant differences in their type of memory deficit, with the ALS group showing impairment only in recognition, whereas aMCI patients showed short and delayed recall performance deficits as well as reduced short-term capacity. Regression analysis revealed a significant impact of executive function on memory performance exclusively for the ALS group, accounting for one fifth of their memory performance. Interestingly, merging all sub scores into a single memory and an executive function score obscured these differences.
  
  
  CONCLUSIONS
  The presented results indicate that the interpretation of neuropsychological scores needs to take the distinct cognitive profiles in ALS and aMCI into consideration. Importantly, the observed memory deficits in ALS were distinctly different from those observed in aMCI and can be explained only to some extent in the context of comorbid (coexisting) executive dysfunction. These findings highlight the qualitative differences in temporal lobe dysfunction between ALS and aMCI patients, and support temporal lobe dysfunction as a mechanism underlying the distinct cognitive impairments observed in ALS.
authors: German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Leipziger Straße 44, 39120 Magdeburg, Germany. judith.machts@dzne.de.
authors: Judith
authors: J
authors: Machts
authors: Verena
authors: V
authors: Bittner
authors: Elisabeth
authors: E
authors: Kasper
authors: Christina
authors: C
authors: Schuster
authors: Johannes
authors: J
authors: Prudlo
authors: Susanne
authors: S
authors: Abdulla
authors: Katja
authors: K
authors: Kollewe
authors: Susanne
authors: S
authors: Petri
authors: Reinhard
authors: R
authors: Dengler
authors: Hans-Jochen
authors: HJ
authors: Heinze
authors: Stefan
authors: S
authors: Vielhaber
authors: Mircea A
authors: MA
authors: Schoenfeld
authors: Daniel M
authors: DM
authors: Bittner
mesh_terms: D000647:Amnesia / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology*; D000690:Amyotrophic Lateral Sclerosis / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology*; D060825:Cognitive Dysfunction / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology*; D056344:Executive Function; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity