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Picture naming in Alzheimer’s disease: The role of episodic memory
Brain and Language 99 (2006) 8–219 www.elsevier.com/locate/b&l
Picture naming in Alzheimer’s disease: The role of episodic memory Jeff Small *, Nirmaljeet Sandhu School of Audiology and Speech Sciences, University of British Columbia, Canada Accepted 6 July 2006
Introduction Explanations of anomia in Alzheimer’s disease (AD) have appealed to the diminished integrity of semantic representations in memory and/or difficulty accessing those representations. One area of investigation that has received less attention until recently is the relationship between deficits in retrieving information from semantic memory and declines in episodic memory in AD (where recent episodic memories are more negatively affected than remote memories; Sagar, Sullivan, & Corkin, 1991; Small & Perry, 2005). The relative sparing of remote memory in AD has been referred to as a temporally graded memory impairment. Previous research has shown that retrieval of names from semantic memory can be influenced by the episodic autobiographical significance of the names for adults with and without dementia (Westmacott, Black, Freedman, & Moscovitch, 2003; Westmacott, Freedman, Black, Stokes, & Moscovitch, 2004). In the present study, we investigated whether the retrieval of object names from semantic memory by persons with AD may be affected by episodic memory, and in particular, the depicted era of the object to be named. Our first hypothesis was that persons with AD would have more success naming objects depicted from an earlier period in the their lives (‘‘Dated’’) compared to objects depicted in their current form (‘‘Contemporary’’), and that this difference would be greater than for healthy older adults. This prediction was made based on the temporally graded memory deficits observed in AD. Our second hypothesis was that healthy older adults would name uniquely Dated pictures of objects more readily than younger adults, whereas younger adults would show better naming of uniquely Contemporary pictures of objects (replicating Poon & Fozard, 1978). Methods The participants in the study were 18 older adults diagnosed with mildmoderate AD, 20 age- matched healthy adults, and 40 younger adults. A naming task was constructed consisting of 46 drawings of objects distributed across four experimental conditions: Dated-Unique (N = 13), Contemporary-Unique (N = 13), Dated-Common (N = 10), and Contemporary-Common (N = 10). Pictures of items in the Dated-Unique condition were objects commonly used during the early 20th century
*
Corresponding author. Fax: +1 604 822 6569. E-mail address: [email protected] (J. Small).
doi:10.1016/j.bandl.2006.06.076
(1910–1940; e.g., bloomers, churn). Pictures in the Contemporary-Unique condition were objects that gained widespread use after the 1970’s (e.g., treadmill, microwave oven). Items in the Common-Dated and CommonContemporary conditions were the same items, but were different in their pictorial form (e.g., dated vs. contemporary picture of camera). Participants were instructed to name each picture. Order of presenting Dated and Contemporary pictures of the same item was counterbalanced across participants. Results The results from a repeated measures ANOVA indicated significant main effects of group (AD, older, younger) and Uniqueness (Common vs. Unique) (see Fig. 1). The AD group scored significantly lower overall (46%) than either the older (76%) or younger (75%) groups F(2, 75) = 46.01, p < .001. Performance on Common items (84%) was significantly better than performance on Unique items (48%) F(1, 75) = 646.75, p < .001. A significant Group by Era interaction indicated that whereas the older and AD groups performed better in the Dated than the Contemporary conditions, the younger group performed better in the Contemporary than in the Dated conditions F(2, 75) = 142.76, p < .001. Comparisons of the AD and older groups showed no significant difference in the effects of Era F(1, 36) = .42, p > .05. A significant Group by Uniqueness interaction F(2, 75) = 16.04, p < .001 indicated a greater advantage for Common items relative to Unique items for the AD group than the other two Groups. A significant three-way interaction between Group, Era and Uniqueness F(2, 75) = 38.39, p < .001 reflected the different effects of Era on the older and younger groups, particularly in the Unique condition. Namely, the older group performed better in the Unique-Dated than the Unique-Contemporary condition, whereas the younger group was more successful naming Unique-Contemporary than Unique-Dated items. Discussion Our first hypothesis was not supported in that both AD participants and healthy older adults named pictures of Dated objects more successfully than Contemporary objects. The lack of group difference indicates that more accurate naming of Dated than Contemporary items by participants with AD cannot be attributed to their temporally graded episodic memory deficit. On the other hand, AD participants’ better naming of Common than Unique items suggests that their naming ability was affected more by the cumulative frequency of using an item over their life-
Abstracts / Brain and Language 99 (2006) 8–219
135
100% 90%
AD Older Younger
80% 70% 60% 50% 40% 30% 20% 10% 0% Dated Unique
Contemporary Unique
Dated Common
Contemporary Common
Fig. 1. Percent Correct (and SE bars) by Group and Condition.
time than by the era in which an item first appears. This finding supports a connectionist principle that repeated use of words produces stronger representations and connections in semantic memory. Our second hypothesis was supported in that younger and older adults showed reverse differences in performance on Contemporary versus Dated items, especially when the items were Unique to an era. The latter result is consistent with findings that older adults are more successful in naming pictures of items that are acquired early than late in life (Hodgson & Ellis, 1998). Thus, the ‘‘reminiscence bump’’ that has been observed for autobiographical events may have a corollary in the domain of lexical-semantic processing.
References Hodgson, C., & Ellis, A. (1998). Last in, first to go: Age of acquisition and naming in the elderly. Brain and Language, 64, 146–163.
Poon, L., & Fozard, J. (1978). Speed of retrieval from long-term memory in relation to age, familiarity, and datedness of information. Journal of Gerontology, 33(5), 711–717. Sagar, H., Sullivan, E., & Corkin, S. (1991). Autobiographical memory in normal ageing and dementia. Behavioural Neurology, 4, 235–248. Small, J., & Perry, J. (2005). ‘‘Do you remember?’’ How caregivers question their spouses who have Alzheimer’s disease and the impact on communication. Journal of Speech, Language, and Hearing Research, 48, 125–136. Westmacott, R., Black, S., Freedman, M., & Moscovitch, M. (2003). The contribution of autobiographical significance to semantic memory: Evidence from Alzheimer’s disease, semantic dementia, and amnesia. Neuropsychologia, 42, 25–48. Westmacott, R., Freedman, M., Black, S., Stokes, K., & Moscovitch, M. (2004). Temporally graded semantic memory loss in Alzheimer’s disease: Cross-sectional and longitudinal studies. Cognitive Neuropsychology, 21(2/3/4), 353–378.
Picture naming in Alzheimer’s disease: The role of episodic memory Jeff Small *, Nirmaljeet Sandhu School of Audiology and Speech Sciences, University of British Columbia, Canada Accepted 6 July 2006
Introduction Explanations of anomia in Alzheimer’s disease (AD) have appealed to the diminished integrity of semantic representations in memory and/or difficulty accessing those representations. One area of investigation that has received less attention until recently is the relationship between deficits in retrieving information from semantic memory and declines in episodic memory in AD (where recent episodic memories are more negatively affected than remote memories; Sagar, Sullivan, & Corkin, 1991; Small & Perry, 2005). The relative sparing of remote memory in AD has been referred to as a temporally graded memory impairment. Previous research has shown that retrieval of names from semantic memory can be influenced by the episodic autobiographical significance of the names for adults with and without dementia (Westmacott, Black, Freedman, & Moscovitch, 2003; Westmacott, Freedman, Black, Stokes, & Moscovitch, 2004). In the present study, we investigated whether the retrieval of object names from semantic memory by persons with AD may be affected by episodic memory, and in particular, the depicted era of the object to be named. Our first hypothesis was that persons with AD would have more success naming objects depicted from an earlier period in the their lives (‘‘Dated’’) compared to objects depicted in their current form (‘‘Contemporary’’), and that this difference would be greater than for healthy older adults. This prediction was made based on the temporally graded memory deficits observed in AD. Our second hypothesis was that healthy older adults would name uniquely Dated pictures of objects more readily than younger adults, whereas younger adults would show better naming of uniquely Contemporary pictures of objects (replicating Poon & Fozard, 1978). Methods The participants in the study were 18 older adults diagnosed with mildmoderate AD, 20 age- matched healthy adults, and 40 younger adults. A naming task was constructed consisting of 46 drawings of objects distributed across four experimental conditions: Dated-Unique (N = 13), Contemporary-Unique (N = 13), Dated-Common (N = 10), and Contemporary-Common (N = 10). Pictures of items in the Dated-Unique condition were objects commonly used during the early 20th century
*
Corresponding author. Fax: +1 604 822 6569. E-mail address: [email protected] (J. Small).
doi:10.1016/j.bandl.2006.06.076
(1910–1940; e.g., bloomers, churn). Pictures in the Contemporary-Unique condition were objects that gained widespread use after the 1970’s (e.g., treadmill, microwave oven). Items in the Common-Dated and CommonContemporary conditions were the same items, but were different in their pictorial form (e.g., dated vs. contemporary picture of camera). Participants were instructed to name each picture. Order of presenting Dated and Contemporary pictures of the same item was counterbalanced across participants. Results The results from a repeated measures ANOVA indicated significant main effects of group (AD, older, younger) and Uniqueness (Common vs. Unique) (see Fig. 1). The AD group scored significantly lower overall (46%) than either the older (76%) or younger (75%) groups F(2, 75) = 46.01, p < .001. Performance on Common items (84%) was significantly better than performance on Unique items (48%) F(1, 75) = 646.75, p < .001. A significant Group by Era interaction indicated that whereas the older and AD groups performed better in the Dated than the Contemporary conditions, the younger group performed better in the Contemporary than in the Dated conditions F(2, 75) = 142.76, p < .001. Comparisons of the AD and older groups showed no significant difference in the effects of Era F(1, 36) = .42, p > .05. A significant Group by Uniqueness interaction F(2, 75) = 16.04, p < .001 indicated a greater advantage for Common items relative to Unique items for the AD group than the other two Groups. A significant three-way interaction between Group, Era and Uniqueness F(2, 75) = 38.39, p < .001 reflected the different effects of Era on the older and younger groups, particularly in the Unique condition. Namely, the older group performed better in the Unique-Dated than the Unique-Contemporary condition, whereas the younger group was more successful naming Unique-Contemporary than Unique-Dated items. Discussion Our first hypothesis was not supported in that both AD participants and healthy older adults named pictures of Dated objects more successfully than Contemporary objects. The lack of group difference indicates that more accurate naming of Dated than Contemporary items by participants with AD cannot be attributed to their temporally graded episodic memory deficit. On the other hand, AD participants’ better naming of Common than Unique items suggests that their naming ability was affected more by the cumulative frequency of using an item over their life-
Abstracts / Brain and Language 99 (2006) 8–219
135
100% 90%
AD Older Younger
80% 70% 60% 50% 40% 30% 20% 10% 0% Dated Unique
Contemporary Unique
Dated Common
Contemporary Common
Fig. 1. Percent Correct (and SE bars) by Group and Condition.
time than by the era in which an item first appears. This finding supports a connectionist principle that repeated use of words produces stronger representations and connections in semantic memory. Our second hypothesis was supported in that younger and older adults showed reverse differences in performance on Contemporary versus Dated items, especially when the items were Unique to an era. The latter result is consistent with findings that older adults are more successful in naming pictures of items that are acquired early than late in life (Hodgson & Ellis, 1998). Thus, the ‘‘reminiscence bump’’ that has been observed for autobiographical events may have a corollary in the domain of lexical-semantic processing.
References Hodgson, C., & Ellis, A. (1998). Last in, first to go: Age of acquisition and naming in the elderly. Brain and Language, 64, 146–163.
Poon, L., & Fozard, J. (1978). Speed of retrieval from long-term memory in relation to age, familiarity, and datedness of information. Journal of Gerontology, 33(5), 711–717. Sagar, H., Sullivan, E., & Corkin, S. (1991). Autobiographical memory in normal ageing and dementia. Behavioural Neurology, 4, 235–248. Small, J., & Perry, J. (2005). ‘‘Do you remember?’’ How caregivers question their spouses who have Alzheimer’s disease and the impact on communication. Journal of Speech, Language, and Hearing Research, 48, 125–136. Westmacott, R., Black, S., Freedman, M., & Moscovitch, M. (2003). The contribution of autobiographical significance to semantic memory: Evidence from Alzheimer’s disease, semantic dementia, and amnesia. Neuropsychologia, 42, 25–48. Westmacott, R., Freedman, M., Black, S., Stokes, K., & Moscovitch, M. (2004). Temporally graded semantic memory loss in Alzheimer’s disease: Cross-sectional and longitudinal studies. Cognitive Neuropsychology, 21(2/3/4), 353–378.