Spatial associations of [18F]FDDNP binding with lower performance on tests of episodic memory and frontal lobe function across groups localized to entorhinal, lateral temporal, parietal, orbitofrontal and dorsolateral prefrontal cortex [39]. Mesial temporal associations with [18F]FDDNP may reflect sensitivity to neurofibrillary tangles in these regions. Although associations between PET imaging sellckchem measures of neuropathology and memory performance are evident in analyses combining impaired and unimpaired individuals, relationships with memory performance within a diagnostic group are more complex (Tables ?(Tables11 and ?and2).2). As summarized in Table ?Table1,1, the correlations between cross-sectional measures of A?? burden using PiB and cognitive performance in AD patients tend to be absent to weak [28,35,37,40].

In MCI, some but not all studies indicate that higher A?? burden is associated with lower performance on tests of episodic memory [35,37,41]. A recent study from a larger cohort of 57 MCI participants from the AIBL study on aging showed only a trend to a relationship between higher neocortical A?? burden and lower long delay free recall performance on the California Verbal Learning Test, a measure of verbal memory [7]. Table 1 Cross-sectional associations between PiB-assessed ??-amyloid burden and cognition in AD and MCI Table 2 Associations between ??-amyloid burden and cognition in cognitively normal individuals Associations between A?? and cognitive performance are even more variable in studies of CN individuals. Table ?Table22 summarizes findings from cross-sectional studies of CN older adults.

Several investigations have shown negative cross-sectional correlations between PiB retention and measures of episodic memory [19,41,42], and one study indicated that cognitive reserve, measured by the National Adult Reading Test, may modify this association [33]. However, the largest study of 177 CN adults found no significant cross-sectional correlations with episodic memory [7], suggesting that a few PiB-positive individuals may have a Anacetrapib large influence on findings in smaller samples. The varied results across studies highlight the complexity of the relationship between cognitive performance and amyloid deposition at the earliest stages of cognitive decline. The few longitudinal investigations of cognitive change in relation to A?? burden have more consistently shown associations for cognitively healthy individuals (Table ?(Table2).2). For example, Villemagne and colleagues [43] reported that greater decline in word list recall was associated with higher A?? deposition in nondemented elderly who ultimately progressed to MCI/AD but not in individuals HTS who remained cognitively normal [43].