Following hard on the heels of a prominent athlete claiming that depression was basically self-inflicted and/or voluntary, we have a paper in Scientific Reports that unequivocally demonstrates the biological basis of anxiety.
The paper, entitled "Neural Circuitry Governing Anxious Individuals’ Mis-allocation of Working Memory to Threat," details research by Daniel M. Stout (of the University of California-San Diego), Alexander J. Shackman (of the University of Maryland), and Walker S. Pedersen, Tara A. Miskovich, and Christine L. Larson (of the University of Wisconsin). The authors write:
Heightened levels of dispositional anxiety confer increased risk for the development of internalizing disorders, including anxiety and co-morbid depression. These debilitating psychiatric disorders are common and existing treatments are inconsistently effective, underscoring the need to develop a deeper understanding of the mechanisms governing individual differences in risk...
Building on prior behavioral and electrophysiological work, functional MRI (fMRI) was used in the present study to quantify neural activity while subjects performed a well-established emotional [working memory] task... The results of our mediation analyses suggest that the amygdala promotes the mis-allocation of [working memory] resources to threat-related distracters. The amygdala is sensitive to a broad spectrum of emotionally salient stimuli, including threat-related facial expressions. In addition, there is clear evidence that anxious individuals show amplified or prolonged amygdala responses to threat-related faces, even when they are task-irrelevant, consistent with our results. Anatomically, the amygdala is well positioned to prioritize the short-term retention of threat-related cues...
[I]t has become clear that information can enter [working memory] via either perceptual encoding or retrieval from long-term memory. From this perspective, [working memory] reflects the temporary allocation of selective attention to recently perceived items or the temporary re-activation of representations stored in [long-term memory]... This suggests that intrusive memories may reflect the mis-allocation of [working memory] resources to distressing material held in [long-term memory].Put more simply, in anxious people, threat-related long-term memories "leak across" into the working memory, the short-term memory system we use to keep track of everyday occurrences. This is mediated through increased activity in the amygdala, a part of the limbic system of the brain long known to have a connection to anxiety, stress, and obsessive behavior. In an interview with PsyPost, study lead author Daniel M. Stout explained this in more detail:
Anxiety and depressive disorders are very common, challenging to treat, and pose an enormous burden on public health. Having an anxious personality is associated with developing future psychological disorders.
We were interested in this topic because we do not fully understand why individuals with an anxious disposition, like those with an anxiety or depressive disorder, experience high levels of emotional distress in the absence of immediate threat, and spend an excessive amount of time thinking about potential dangers in objectively safe situations.
These types of symptoms are particularly pernicious because they inflict their damage when we need to be focusing on the task-at-hand or at times when we don’t want them to (e.g., during a meeting at work, talking to loved ones, when trying to fall asleep at night). If we can understand what underlies these symptoms, and the brain mechanisms involved, we may be better able to reduce the suffering that many people with high levels of anxiety report.
Earlier work by our group using EEG technology suggested that this might reflect problems with how anxious individuals process threat-related information in working memory. Working memory is a short-term memory system that guides on-going thoughts and behaviors. It is the memory system involved in helping us remember things while we do a task, like remembering a phone number while dialing it.
If threat-related information gains access to or ‘contaminates’ working memory, it can exert a negative influence on our thoughts and actions. For instance, viewing an e-mail informing you that a bill is due can result in increased anxiety and intrusive thoughts about financial troubles; triggering a chain-reaction of uncontrolled worry that spans the entire day.
One other important aspect of working memory is that its capacity is limited, so we can only hold a finite amount of information online in working memory at any given time. So, if your working memory is ‘working’ on the worry-related thoughts, then less working memory capacity is available to attend to tasks important for your job or activities you are trying to complete.Which certainly squares with my experience. I have a good deal of social anxiety, and it doesn't seem to matter that I objectively, rationally know that I'm safe, that none of the people in the room are judging me or dislike me (or, honestly, are probably thinking about me at all). The sensation is of having two brains; the rational one, that says, "These are your friends, there's no reason to freak out," and the emotional reptile brain that says, "I AM FREAKING OUT."
[image courtesy of the Wikimedia Commons]
This fMRI study shows how such a disorder can occur, and what is happening in the brain during an anxiety attack -- allowing a much more targeted approach to treating it. It's to be hoped that other researchers will take this study and run with it. Because there's no other way to put it: anxiety sucks.