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SNAC-K

Kungsholmen | Kungsholmen Panorama Skinnarviksberget
© Holger Ellgaard

The Swedish National Study on Aging and Care in Kungsholmen (SNAC-K) is conducted by the Aging Research Center (ARC), Karolinska Institutet, in collaboration with the Stockholm Gerontology Research Center. It has been promoted and supported by the Swedish Ministry for Social Affairs since 1999 as one of four subprojects of the Swedish National Study on Aging and Care (SNAC).

The SNAC-K dataset is based on several hours of clinical examination (an interview and several questionnaires on health and lifestyle, a medical examination as well as cognitive assessment) of people aged over 60 years who live in the area of Kungsholmen/Essingeöarna (one of the 14 islands) in Stockholm. The general purpose of SNAC-K is to address questions regarding Swedish older adults’ medical, psychological, and social health. With its large number of subjects and its range of cognitive, health, lifestyle, social, genetic, and brain data, SNAC-K provides a unique dataset to investigate variables that may account for the selective associative deficit in older adults.

A newly assessed cohort of 584 60-year-old adults, who participated in an item-associative memory test, is of particular interest. In this test participants memorized item associations (i.e., face–scene pairs) as well as individual items (i.e., faces or scenes). This makes it possible to distinguish between variables that influence episodic memory in general, or the associative component specifically.

Structural Brain Correlates of Associative Memory in Older Adults

Aim

This study aimed to assess structural brain differences related to inter-individual differences in associative memory performance in older adults.

Background

In comparison to memory for single items, associative memory declines greatly in aging (Chalfonte & Johnson, 1996; Naveh-Benjamin, 2000). However, older individuals vary substantially in their ability to memorize associative information (Brehmer et al., 2007; Nyberg et al., 2003). Although functional studies link associative memory to the medial temporal lobe (MTL) and prefrontal cortex (PFC; Cabeza, 2006; Mayes et al., 2007), little is known about how volumetric differences in the MTL, PFC, and other brain regions contribute to individual differences in associative memory.

Methods

We investigated regional gray-matter volume related to individual differences in associative memory in a sample of healthy older adults (N = 54; age 60 years; SNAC-K sample). To differentiate item from associative memory, participants intentionally learned face–scene picture pairs before performing a recognition task that included single faces, scenes, and face–scene pairs. Gray-matter volumes were analyzed using a voxel-based morphometry (VBM) whole-brain as well as a region-of-interest- (ROI-) based approach (i.e., MTL, PFC). To examine volumetric differences specific to associative memory, item memory was controlled for in the analyses.

Results

The study participants differed in their memory for associative information despite similarly good memory performances for information presented at the learning stage. Large inter-individual differences were observed in false memories of information that had not been presented at the learning stage, but was newly presented in the recall phase (false alarms; cf. Figure, top). Interestingly, associative memory was independent of individuals’ ability to remember single items.

Older adults with better associative memory showed larger gray-matter volumes primarily in regions of the left and right lateral PFC (see Figure, bottom), in addition to the left occipital lobe, and left cerebellum.

Conclusion

These findings provide evidence for the importance of the PFC in intentional learning of associations, likely because of its involvement in organizational and strategic processes that distinguish older adults with good, from those with poor associative memory (see Becker et al., 2015).

Figure 1

Figure 1 |Above panel: Hit (H) and false-alarm (FA) rates in the associative-
© Becker et al., 2015

Collaboration SNAC-K

Publication

Becker, N., Laukka, E. J., Kalpouzos, G., Naveh-Benjamin, M., Bäckman, L., & Brehmer, Y. (2015). Structural brain correlates of associative memory in older adults. NeuroImage, 118, 146–153. doi: 10.1016/j.neuroimage.2015.06.002