Abstract
Younger adults with anxiety disorders are known to show an attentional bias toward negative information. Little is known regarding the role of biased attention in anxious older adults, and even less is known about the neural substrates of any such bias. Functional magnetic resonance imaging (fMRI) was used to assess the mechanisms of attentional bias in late life by contrasting predictions of a top-down model emphasizing deficient prefrontal cortex (PFC) control and a bottom-up model emphasizing amygdalar hyperreactivity. In all, 16 older generalized anxiety disorder (GAD) patients (mean age=66 years) and 12 non-anxious controls (NACs; mean age=67 years) completed the emotional Stroop task to assess selective attention to negative words. Task-related fMRI data were concurrently acquired. Consistent with hypotheses, GAD participants were slower to identify the color of negative words relative to neutral, whereas NACs showed the opposite bias, responding more quickly to negative words. During negative words (in comparison with neutral), the NAC group showed PFC activations, coupled with deactivation of task-irrelevant emotional processing regions such as the amygdala and hippocampus. By contrast, GAD participants showed PFC decreases during negative words and no differences in amygdalar activity across word types. Across all participants, greater attentional bias toward negative words was correlated with decreased PFC recruitment. A significant positive correlation between attentional bias and amygdala activation was also present, but this relationship was mediated by PFC activity. These results are consistent with reduced prefrontal attentional control in late-life GAD. Strategies to enhance top-down attentional control may be particularly relevant in late-life GAD treatment.
Highlights
In younger anxious individuals, attention is inordinately captured by negative cues, giving rise to an attentional bias.[1,2,3] Despite the fact that anxiety disorders are prevalent in older adults,[4] the impact of aging on attentional bias has received very little attention from researchers, with only 3 published studies[5,6,7] as compared with 4200 studies in younger adults.[1]
The purpose of this study was to explore the neural substrates of attentional bias in late-life generalized anxiety disorder (GAD), one of the most prevalent psychiatric conditions in older adults[22] and a disorder reliably linked to attentional bias effects in younger samples.[23]
Applying a small volume correction to the amygdala revealed a cluster in the left basolateral amygdala for which the GAD group showed greater negative vs neutral contrast values than did the non-anxious control (NAC) group
Summary
Attention is inordinately captured by negative cues, giving rise to an attentional bias.[1,2,3] Despite the fact that anxiety disorders are prevalent in older adults,[4] the impact of aging on attentional bias has received very little attention from researchers, with only 3 published studies[5,6,7] as compared with 4200 studies in younger adults.[1]. An individual with a more reactive bottom-up system working to rapidly identify and orient toward threats[10] would likely demonstrate hyperresponsivity of the amygdala, the principal brain region implicated in the processing of emotional material.[11,12] Alternatively, an individual with a less efficient top-down executive system, who experiences difficulty implementing and enforcing processing routines relevant to task goals in the face of emotional distracters[13] would likely show a pattern of deficient prefrontal cortex (PFC) recruitment.[14] Given these dissociable neural profiles, neuroimaging studies may be uniquely well suited to clarify the model that best explains attentional bias in a given clinical population
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