The complex interaction between anxiety and cognition: insight from spatial and verbal working memory

Abstract

Anxiety can be distracting, disruptive, and incapacitating. Despite problems with empirical replication of this phenomenon, one fruitful avenue of study has emerged from working memory (WM) experiments where a translational method of anxiety induction (risk of shock) has been shown to disrupt spatial and verbal WM performance. Performance declines when resources (e.g., spatial attention, executive function) devoted to goal-directed behaviors are consumed by anxiety. Importantly, it has been shown that anxiety-related impairments in verbal WM depend on task difficulty, suggesting that cognitive load may be an important consideration in the interaction between anxiety and cognition. Here we use both spatial and verbal WM paradigms to probe the effect of cognitive load on anxiety-induced WM impairment across task modality. Subjects performed a series of spatial and verbal n-back tasks of increasing difficulty (1, 2, and 3-back) while they were safe or at risk for shock. Startle reflex was used to probe anxiety. Results demonstrate that induced-anxiety differentially impacts verbal and spatial WM, such that low and medium-load verbal WM is more susceptible to anxiety-related disruption relative to high-load, and spatial WM is disrupted regardless of task difficulty. Anxiety impacts both verbal and spatial processes, as described by correlations between anxiety and performance impairment, albeit the effect on spatial WM is consistent across load. Demanding WM tasks may exert top-down control over higher-order cortical resources engaged by anxious apprehension, however high-load spatial WM may continue to experience additional competition from anxiety-related changes in spatial attention, resulting in impaired performance. By describing this disruption across task modalities, these findings inform current theories of emotion-cognition interactions and may facilitate development of clinical interventions that seek to target cognitive impairments associated with anxiety.

Keywords: anxiety; cognition; electromyography; performance; startle; working memory.

Figure 1

Task run and block structure. (A) Schematic diagram of a sample run with alternating threat and safe n-back blocks. During each n-back block, three acoustic probes were delivered. Shocks were delivered three times during each run (with 0–2 shocks each threat block). (B) Sample verbal 1-back block and internal trial structure. Each block began with an instruction screen, followed by a fixation cross. Eighteen letters were presented in succession during each block, separated by a 2 s ITI (fixation). Participants made a keyboard button press response for every letter presented; one button indicated a target letter (e.g., “r”) and another button indicated a distractor letter (e.g., “n” and “R”). During the view condition subjects attended to the letters without making a button press. (C) Sample spatial 2-back block and internal trial structure. Block structure was identical to the verbal n-back except that spatial stimuli were used. Participants made a keyboard button press response every time a star appeared in one of four locations; one button indicated a target location (e.g., “top”) and another button indicated a distractor location (e.g., “bottom”).

Figure 2

Verbal and spatial n-back performance during threat and safe. Verbal performance was impaired during threat compared to safe when participants were engaged in low-load tasks (1-back and 2-back), but not high-load tasks (3-back). In contrast, spatial performance was impaired during threat compared to safe when participants were engaged in any task, irrespective of difficulty. Error bars represent the within-subjects standard error for the repeated-measures general linear model (GLM) comparing different levels of Load under threat (dark gray bars) and safe (light gray bars) conditions separately. Within-subject standard error was calculated by dividing the square root of the mean standard error for the GLM divided by the square root of n (Masson, 2003). ^*p < 0.01.

Figure 3

The relationship among anxiety-potentiated startle, performance (threat–safe), and state anxiety. Startle potentiation was negatively correlated with verbal and spatial working memory performance, and state anxiety was negatively correlated with verbal and spatial working memory performance. p < 0.05 for all correlations.