Anxiety disorders are the most prevalent mental health conditions. Although they are less visible than schizophrenia, depression, and bipolar disorder, they can be just as disabling. In this post I have tried to include he basics you need to know about anxiety for early diagnosis or prevention.
Anxiety is triggered when the senses pick up a threat, as simple as a loud noise, a scary sight, a creepy feeling. This external information take two different routes through the brain:
- The shortcut. When startled, the brain automatically engages an emergency hot line to its fear centre, the amygdala. Once activated, the amygdala sends the equivalent of an all-points bulletin that alerts other brain structures. The result is the classic fear response which is sweaty palms, rapid heartbeat, increased blood pressure and a burst of adrenaline. All this happens before the mind is conscious of having smelled or touched anything. Before you know why you’re afraid, you are.
- The high road. Only after the fear response is activated does the conscious mind kicks into gear. Some sensory information, rather than traveling directly to the amygdala, takes a more circuitous route, stopping first at the thalamus – the processing hub for sensory cues – and then the cortex – the outer layer of brain cells. The cortex analyses the raw data streaming in through the senses and decides whether they require a fear response. If they do, the cortex signals the amygdala and the body stays on alert.
The body’s response to anxiety is a complex process. By putting the brain on alert, the amygdala triggers a series of changes in the brain chemicals and hormones that out the entire body in anxiety mode.
- Stress hormone boost. Responding to signals from the hypothalamus and pituitary gland, the adrenal glands pump out high levels of the stress hormone cortisol. Too much cortisol short circuits the cells in the hippocampus, making it difficult to organise the memory of a trauma or stressful experience. Memories lose their context and become fragmented.
- Racing Heartbeat. The body’s sympathetic nervous system, responsible for heart rate and breathing, shifts into overdrive. The heart beats faster, blood pressure rises and the lungs hyperventilate. Sweat increases and even the nerve endings on the skin tingle into action, creating goose bumps.
- Fight, Flight or Fright. The senses become hyperalert, drinking in every detail of the surroundings and looking for potential new threats. Adrenaline shoots to the muscles, preparing the body to fight or flee
- Digestion shutdown. The brain stops thinking about things that bring pleasure, shifting its focus instead of identifying potential dangers. To ensure that no energy is wasted on digestion, the body will sometimes respond by emptying the digestive tract through involuntary vomiting, urination or defecation.
I understand that this post would require a glossary for the medical terms so here goes :
- Amygdala – The emotional core of the brain, the amygdala has the primary role of triggering the fear response. Information that passes through the amygdala is tagged with emotional significance.
- Auditory and Visual Stimuli – Sights and sounds are processed first by the thalamus, which filters the incoming cues and shunts them either directly to the amygdala or to the appropriate parts of the cortex.
- Bed Nucleus of the Stria Terminalis – Unlike the amygdala, which starts off and immediate burst of fear, the BNST perpetuates the fear response, causing the longer term case of typical anxiety.
- Cortex – It gives raw sights and sounds meaning, enabling the brain to become conscious of what it is seeing or hearing. One region, the prefrontal cortex may be vital to turning off the anxiety response once a threat has passed.
- Hippocampus – This is the memory center, vital to storing the raw information coming in from the senses, along with the emotional baggage attached to the data during their trip through the amygdala.
- Locus Ceruleus – It receives signals from the amygdala and is responsible for initiating many of the classic anxiety responses, rapid heartbeat, increased blood pressure, sweating and pupil dilation.
- Olfactory and Tactile Stimuli – Smells and touch sensations bypass the thalamus altogether, taking a shortcut directly to the amygdala. Smells, there fore often evoke stronger memories or feelings than do signals or sounds.