Neuroscience of Anxiety


Neuro Transmissions


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Hey there, Brainiacs! I’m Alie Astrocyte, and you’re watching Neuro Transmissions. As most of you probably know, I’m a graduate student. I’m working on getting my PhD in neuroscience. I love my research. Getting to study astrocytes every day is totally awesome! So even though grad school can be stressful sometimes, I love what I do. Not all stress is bad. Stress is actually an important physical response that helps keep us sharp. Short term stress can help improve our alertness and memory. It also motivates us on a daily basis. But as I’ve learned, sometimes stress... isn’t just stress. When stress goes from being a motivator to being totally overwhelming, that’s not normal. A couple years ago, I was diagnosed with generalized anxiety disorder. Generalized anxiety disorder is described by the Anxiety and Depression Association of America as “persistent, excessive, and unrealistic worry about everyday things”. Basically? I was worried. All the time. About everything. Getting a diagnosis from a psychologist was the first step to finding a treatment plan that works for me. Something I’m still navigating everyday. And since I’m a neuroscientist, I got curious about what anxiety meant for my brain. Anxiety disorders include not only Generalized Anxiety Disorder, but also other conditions like social anxiety disorder, PTSD, and panic disorder. The National Institute of Mental Health says that anxiety disorders are the most common mental illness in the United States, affecting nearly 1 in 5 adults. So it’s pretty important for us to figure out how these disorders work, and how to treat them effectively. Just like how the occipital lobe handles vision and the temporal lobe processes sounds, our emotional responses have their own brain regions. The limbic system is a complex set of structures deep inside the brain that includes the hippocampus, amygdala, hypothalamus, and thalamus. This circuit is believed to handle most of our emotional processing, and the prefrontal cortex is responsible for integrating this emotional information into our decision making. Scientists think that anxiety disorders pop up when there are changes in the signaling of the limbic system. Of course, we can’t go digging around in living people’s brains to see how their neurons are firing, but scientists can study this theory using non-invasive imaging techniques, like fMRI and PET scans. This kind of research has found that patients with anxiety disorders have more activity than normal in the limbic system. Importantly, there’s a trend for these patients to have hyperactive amygdalas, which is interesting, because the amygdala is sometimes considered the “fear center” of the brain. Each disorder has its own quirks, too. In panic disorder, the amygdala hyperactivity might be caused by less GABA, the main inhibitory neurotransmitter, in some areas of the brain. This could lead to less inhibitory signaling in the emotion circuits, making it harder to control panicky feelings. Patients with generalized anxiety disorder also seem to have larger amygdalas than controls. So their brains have more machinery to process fear information, which then reacts more strongly to negative emotional stimuli. PTSD, on the other hand, might be a result of too much excitatory signaling in the hippocampus and amygdala, leading to intense emotional reactions to triggering stimuli. PTSD might be partially caused by our logical brain regions being forced to process emotional information, giving our brain a harder time controlling those thoughts. In social anxiety disorder, being exposed to images of faces leads to extra activity in the amygdala. So people who are anxious in social situations are processing social information through a layer of fear, making those environments stressful for them. Like in PTSD, this might be a result of excessive excitatory signaling in the limbic system. Researchers are still working out a lot of the details on how differences in the brain lead to these conditions. The limbic system has a lot of parts, and there’s a lot of variation in the symptoms and severity of each of these disorders. So it can be hard to pick apart the details. For me, anxiety felt like having my stress dial cranked up to eleven. All the time. These go to eleven. I had trouble sleeping, and felt like I was never on top of my to-do list. It actually took me a really long time to admit that how I felt wasn’t just normal grad school stress. And it wasn’t until I started getting treatment that I realize just how bad I actually felt. So how do we treat anxiety disorders? I’ve personally found a combination of cognitive behavioral therapy, usually called CBT for short, and medication to work the best for me. Micah is going to talk about the psychological causes of anxiety and how therapies like CBT are used to treat it in a separate video. Medication can be helpful for some patients, too. The most common drugs prescribed for anxiety disorders are selective serotonin reuptake inhibitors, or SSRIs, which are also commonly prescribed for depression. SSRIs function by inhibiting the reuptake of serotonin, a neurotransmitter. In the brain, serotonin is known to be involved in mood, sleep, and appetite regulation. SSRIs block neurons from reabsorbing serotonin after it’s released, leaving it lingering in the synapse, where it can repeatedly stimulate the receiving neuron and push the neighboring neurons to adjust their serotonin signaling. SSRIs are used for long-term anxiety management. It takes them a while to have an effect, and they help keep moods balanced. It’s not totally clear how SSRIs help with anxiety disorders. It’s not even totally clear how they work. But they do seem to help. Alternatives to SSRIs are serotonin-norepinephrine reuptake inhibitors, or SNRIs. They have very similar effects, but instead of just blocking the reuptake of serotonin, SNRIs block absorption of serotonin and norepinephrine, also called noradrenaline. This neurotransmitter is linked to alertness, attention, and action-readiness. Which medication a patient uses depends on their preferences, and it can take a couple of tries to find the right choice. When patients are dealing with an acute crisis, like a panic attack, short-term, fast-acting medications like benzodiazepines may be more practical. These drugs have a sedative effect, and act as muscle relaxants. Unlike SSRIs and SNRIs, benzodiazepines are considered addictive because of their immediate relaxing effect, and can be easily abused. However it’s treated, there are a lot of options out there for people dealing with anxiety disorders. Getting treatment has really changed my life for the better, and I’m really grateful that scientists and doctors have spent so much time and effort trying to understand these conditions so that people like me can get the help we need. Thanks for watching this episode of Neuro Transmissions! If you liked it, please give it a thumbs up. And hit subscribe to catch more videos about brain diseases and disorders in the future. If you’re really excited to see more videos like this, consider supporting us on Patreon. We couldn’t do all this without your support. You can find me on Twitter @alie_astrocyte if you’d like to know more about my own experience with anxiety. And if you’d like to learn about a particular condition, let us know in the comments! Until our next transmission, I’m Alie Astrocyte. Over and out!