Application of a cognitive neuroscience perspective of cognitive control to late-life anxiety
Introduction
Although cognitive deficits in older individuals with depression have been the focus of numerous investigations, studies have only begun to investigate the relationship between anxiety and cognition. A small but growing literature has suggested there is a negative relationship between late-life anxiety and cognition. A recent critical review revealed weaker cognitive performance on effortful tasks among older adults with clinically significant anxiety symptoms compared with those with minimal or no symptoms (Beaudreau & O’Hara, 2008).
Recent theories (e.g., attention control theory; Eysenck, Derakshan, Santos, & Calvo, 2007) suggest that anxiety shifts cognitive resources away from goal-relevant information toward threat-focused information, and that this reallocation of resources leads to performance differences between anxious and non-anxious adults on cognitively demanding tasks. Converging evidence from multiple studies supports these theories by associating impaired cognitive control ability with self-reported anxiety (Beaudreau & O’Hara, 2009) and anxiety status in older individuals (Broomfield et al., 2007, Mantella et al., 2007; see Price & Mohlman, 2007 for an alternative view). The term ‘cognitive control’ refers to processes associated with goal-directed behavior in a mechanistic definition of ‘executive functions’ (Miller & Cohen, 2001). The current review examines the relationship between late-life anxiety and cognitive control from cognitive neuroscience and cognitive aging perspectives. Independent roles for aging, anxiety and their interaction are proposed.
Notably, comorbidity of anxiety and depression is widespread in the older population (Hek et al., 2011). Depressive symptoms and episodes frequently coexist with clinically significant anxiety symptoms and generalized anxiety disorder (GAD) in older age (Mackenzie et al., 2011, Richardson et al., 2011, Wolitzky-Taylor et al., 2010). The pervasiveness of co-existing late-life anxiety and depression has led to interest in combinations of these symptoms, particularly major depressive disorder (MDD) with anxiety symptoms referred to as ‘anxious depression.’ This review therefore encompasses late-life investigations of cognitive control in adults with GAD and anxious depression.
Studies of late-life anxiety or anxious depression and cognition that focus on cognitive control typically examine how anxious older individuals deal with the interference associated with negative emotion. Interference is generally measured in studies of anxiety by incorporating emotional content into the standard Stroop paradigm (Stroop, 1935). Resultant effects reflect the impact of negatively valenced stimuli (MacLeod & Rutherford, 1992) and emotional conflict (i.e., incongruence of emotion words and faces vs. congruence; Etkin, Egner, Peraza, Kandel, & Hirsch, 2006) on cognitive control. Although the literature has focused predominantly on Stroop interference associated with anxiety, the issue can be conceptualized as a more general problem of how an individual minimizes the interference caused by task-irrelevant information. A cognitive neuroscience framework may prove useful for elucidating the relationship of interference effects and cognitive control.
‘Top-down processing’ is a term often used interchangeably with ‘cognitive control processing’ to describe voluntary control of attention (Hirsch & Mathews, 2012). Deficient top-down processing has been shown to increase processing of threat information, and thus represents one possible contributor to states such as pathological worry (Hirsch & Mathews, 2012), including generalized anxiety disorder (GAD; MacLeod and Rutherford, 1992, MacLeod and Rutherford, 2004). Others have argued against such claims by suggesting that threat evaluation occurs before top-down processes could influence processing (Mogg & Bradley, 1998). Recent behavioral and imaging data suggest a role for both top-down and bottom-up processing of information during effortful tasks performed while in an anxious state (Reeck, LaBar, & Egner, 2012). Thus, complex interactions between both top-down and bottom-up processing appear to influence processing of threat-related information. Narrowing the focus of investigation to such factors allows for more precision in elucidating the relationship between late-life anxiety and cognition. For example, normal aging affects late-life cognitive processing even in the absence of anxiety, and therefore, any interactions with anxiety must be considered above and beyond the independent effects of aging.
Section snippets
Cognition in normal aging
Older adulthood gives rise to notable complexity and change in emotional processing (Scheibe & Carstensen, 2010) and cognitive functioning (Bosworth & Schaie, 1999). Older adults are believed to show greater emotional wellbeing and emotional stability, increased orientation to positive stimuli (Scheibe & Carstensen, 2010), and greater complexity and differentiation of emotional response to negative stimuli than their younger counterparts (Beaudreau, MacKay, & Storandt, 2009). The extent to
Late-life anxiety and cognitive control
Behavioral studies of clinically significant anxiety and cognitive control generally implicate increased interference on the Stroop task. Although increased interference is expected for both emotional and non-emotional versions of the Stroop task (Banich et al., 2009), Stroop performance in anxious older adults varies both by the version (emotional vs. neutral) and anxiety severity and type. Table 1 provides an overview of the results from late-life anxiety studies of cognitive control. As
Neurobiological evidence
Neuroimaging studies of cognitive control in older adults with anxiety disorders or anxious depression have provided a plausible biological explanation of observed behavioral findings between older anxious and nonanxious individuals, and between older and younger anxious adults. Regardless of the emotional content of the stimuli, regions of the dorsolateral prefrontal cortex (DLPFC) activate when attentional demands increase in the context of conflict arising from color incongruence or the
Discussion
Several observations and testable hypotheses emerge from the reviewed cognitive and emotional aging theories and behavioral and neuroimaging findings. First, age and anxiety independently affect cognitive control. A simple cognitive model of general slowing explains age-related cognitive control deficits on tasks with interfering irrelevant information (Verhaeghen, 2011, Verhaeghen and De Meersman, 1998); however, some age-related deficits on cognitive control tasks persist after accounting for
Implications and conclusions
Mohlman (2005) proposed that executive dysfunction due to deficits in PFC functioning potentially moderates treatment outcome among older adults with GAD. In a recent study of neuropsychological predictors of treatment response in late-life GAD, Butters et al. (2011) found that healthy controls had better baseline cognitive control in addition to better neuropsychological performance on a number of measures. Notably, in the GAD group treated with 12-weeks of an SSRI (escitalopram), improvement
Acknowledgements
We wish to thank Ms. Kaycee Rashid and Brittany Cerbone for their assistance with references and Ms. Katherine Lou and for reviewing and providing feedback on revisions.
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