Exaggerated Reaction to Novelty and Preclinical Cognitive Decline

Early detection of abnormal cognitive decline is important (Evans, Grodstein, Loewenstein, Kaye, & Weintraub, 2011; Sperling et al., 2011). However, the challenge is not to identify individuals who already show measurable cognitive change (i.e., Mild Cognitive Impairment; MCI), but rather to identify those individuals who appear cognitively normal, but are at an increased risk for imminent cognitive deterioration. Identifying such individuals is important because pre-clinical cognitive decline is associated with functional decline (Rajan, Hebert, Scherr, Mendes de Leon, & Evans, 2013; Riddle, McQuoid, Potter, Steffens, & Taylor, 2015), placing individuals at risk for serious functional mistakes in daily life (e.g., mismanagement of medications, falls, etc.; Degrauw, Annest, Stevens, Xu, & Coronado, 2016; Plehn, Marcopulos, & McLain, 2004; U.S. Consumer Product Safety Commission, 2003). This risk is compounded when physicians and family members are not aware of the covert changes in a patient’s cognition.

The principal barrier to progress in this research is that most individuals can compensate for subtle declines in cognition (Buckner, 2004; Clément & Belleville, 2010). Such compensation is particularly successful within the structured format of neuropsychological testing (Kenworthy, Yerys, Anthony, & Wallace, 2008), allowing cognitively-declining patients to produce performances that are indistinguishable from those of neurocognitively-healthy peers (Mortimer, Borenstein, Gosche, & Snowdon, 2005). These issues are further complicated by the fact that the degree of compensation varies among people, reflecting individual differences in cognitive and neural reserves (Stern, 2009; Tucker & Stern, 2011). Thus, typical risk factors (e.g., genetic background, neurodegenerative changes) are not adequate for predicting when, or whether, a person will decline cognitively (Bertram, Lill, & Tanzi, 2010; Crystal et al., 1988).

The projects in the Executive Lab that investigate preclinical cognitive decline have focused on  a promising marker of incipient cognitive decline: exaggerated reaction to novelty. In prior work, we have shown that two different approaches to operationalizing exaggerated reaction to novelty can serve as predictors of incipient cognitive decline: (a) novelty-induced increases in action (or “motor”) planning latencies (Suchy, Kraybill, & Franchow, 2011), and (b) decreases in Openness to experience (Williams, Suchy, & Kraybill, 2013).  Furthermore, we have shown that these two markers together account for between 13% to 18% of variance in cognitive change above and beyond other typical neuropsychological predictors of decline among older adults, such as memory tests, dementia screening measures, and depressive symptoms (Suchy, Franchow, Neirmeyer, Ziemnik, Williams, Pennington, in press).