Patterns of autobiographical memory impairment according to disease severity in semantic dementia.
Studies of autobiographical memory in semantic dementia (SD) have yielded either a reversed temporal gradient or spared performances across the entire lifetime. This discrepancy might be owing to the fact that these studies did not take into account disease severity. Our aim was to study patterns of autobiographical memory impairment according to disease severity and to unravel their mechanisms in 14 SD patients, using an autobiographical memory task assessing overall and strictly episodic memories across the entire lifetime. We divided our patients in 2 subgroups of 7 patients each, one mild and one moderate according to their level of disease severity. The results indicated for the mild subgroup selective preserved performances for the most recent time period (last 12 months period) for both autobiographical memory scores. In the moderate subgroup, performances were impaired for both scores whatever the time period. Within-group comparisons across time periods showed a recency effect and a reminiscence bump in the mild subgroup and only a less important recency effect in the moderate subgroup, suggesting that with disease severity, old memories (reminiscence bump) tend to vanish and even recent memories are less well retrieved. A correlation analysis was carried out on the entire group, between the overall autobiographical memory score and performances provided by a general cognitive evaluation (semantic memory, executive functions, working and episodic memory). The results of this analysis reflect that mechanisms of disruption of autobiographical memory in SD predominantly involve a deficit of storage of semantic information in addition to faulty executive retrieval strategies. Finally, our result and those of the literature suggest the existence of 3 distinct autobiographical memory impairment patterns in SD according to disease severity: firstly preserved performances whatever the time period, secondly a reversed temporal gradient with a reminiscence bump and thirdly the appearance of a "step-function".
Matuszewski
Vanessa
V
Inserm - EPHE - Université de Caen Basse - Normandie, Unité de recherche U 923, GIP Cyceron, CHU Côte de Nacre, Caen, France.
Piolino
Pascale
P
Belliard
Serge
S
de la Sayette
Vincent
V
Laisney
Mickaël
M
Lalevée
Catherine
C
Pélerin
Alice
A
Viader
Fausto
F
Eustache
Francis
F
Desgranges
Béatrice
B
D000368:Aged; D001037:Aphasia / Q000150:complications / Q000503:physiopathology*; D003210:Concept Formation; D003704:Dementia / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008568:Memory / Q000145:classification; D008569:Memory Disorders / Q000145:classification* / Q000150:complications; D011939:Mental Recall; D008875:Middle Aged; D012649:Self Concept; D012660:Semantics; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D014705:Verbal Behavior