Research on mice brain cells reveals the possible causes of anxiety

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an illustration showing a brain affected with anxiety
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(Last Updated On: December 19, 2018)

Anxiety is the most common type of mental condition affecting 1/8th of the total population around the world (Dhawan, Kumar et al. 2001). It is a feeling of fear, nervousness, panic, and worries about something with unknown and doubtful outcomes.

People often confuse anxiety with depression. In anxiety, the intimidation that one experiences are future-oriented. The fear is predicated upon the idea as to ‘what if’ anything of such hurtful nature happens in future. Whereas with depression, there is a history involved.  Any event of the past triggers the chain of thoughts that lead to one thinking of all the worst-case scenarios that could happen.

Types of anxiety disorders:

Following are some of the types of anxiety disorders:

  1. Panic disorder:

A panic attack is a feeling of terror and fear. A person experiencing a panic attack becomes sweat and may experience chest pain. Sometimes a person may feel like having a heart attack.

  1. Illness anxiety disorder:

Illness anxiety disorder is the anxiety about your health.

  1. Phobia:

Phobia is the extreme fear of something. It might be an object, situation, and activity. For example, people often fear heights and flying.

  1. Social Anxiety Disorder:

In Social Anxiety Disorder, the person experiences an intense fear of being judged by other people in a social situation.

  1. Generalized Anxiety Disorder:

In a Generalized Anxiety Disorder, one gets worried without any solid reason.

SAD

Marked Fear of Social Situations

GAD

Worry that Lasts for Months

PD

Recurrent  Panic Attacks

  • Nauseous when people are around
  • Blushing, sweating
  • Hard time talking to people
  • Staying away from crowded places
  • Fear of being judged or humiliated or embarrassed
  • Feeling wound up or over the edge
  • Easily fatigued
  • Irritability
  • Difficulty in concentrating
  • Blanking out
  • Sleep problems  (unsatisfying sleep, difficulty in sleeping)
  • Sudden and repeated attacks of intense fear
  • The feeling of being out of control during PA
  • Avoidance of places where PAs have occurred previously
  • Dreading the next PA

SAD: Social Anxiety Disorder

GAD: Generalized Anxiety Disorder

PD: Panic Disorder

Its Symptoms

  • Panic
  • Feelings of fear
  • Cold
  • Nausea
  • Dizziness
  • Feeling numb
  • Problem in breathing
  • difficulty in sleeping
  • Tension
  • Not staying calm
  • Tingling hands or feet
  • Uneasiness
  • excessively sweating
  • Increased in heart rate

Previous researches on Anxiety:

The neurobiological mechanisms that lead to anxiety, however, may not be completely known but recent studies tell us that the dysfunction of the amygdala, hippocampus, medial prefrontal cortex, and anterior cingulate cortex may be the cause ((Cannistraro and Rauch 2003).

GABA neurotransmission has been known to have a role in anxiety for quite a while. However, the data on GABA receptor-mediated role in anxiety is limited (Millan 2003). This could be because the investigators, for far too long, have relied on baclofen for analysis which has a very limited range of efficacy before confounding side-effects begin to manifest in anxiety paradigms (Dalvi and Rodgers 1996).

GABA receptors became the center of interest when a study on mice revealed increased anxiety in GABA (Bettler, Kaupmann et al. 2004) deficient mice during light-dark box and staircase test. Moreover, these mice also showed a panic-like response on an elevated zero mazes and quickly jump off (Mombereau, Kaupmann et al. 2004). This evidence clearly suggests that GABA receptors activation might reduce anxiety.

5-Hydroxytryptamine is excitatory and inhibitory neurotransmitter site of 5-HT neurotransmitters (serotonin). These ligand-gated channels are found in central and peripheral nervous systems. A decrease in serotonin level occurs in a condition like anxiety and depression. GABA is Gamma-Amino Butyric Acid that acts as a neurotransmitter in our body.

Ongoing Experimental Research:

An experimental research is being conducted on mice. The hippocampus (the part of the brain) in the mice is similar to that of humans’. Response to the situations of fear and anxiety, therefore, will also be similar. It is still unknown to the researchers exactly which neurons in the brain are accountable for producing the feeling of distress, panic, and fear.

In order to identify and discover the cells at work, scientists from Columbia University, the University of California, San Francisco, and other institutions settled mice in a maze with routes leading to open areas.

Inside the maze, mice were made to experience worrisome conditions in extensive environments. The researchers monitored the hippocampus closely while the mice were subjected to stress.

The researchers observed a unique collection or a group of cells lighting up when the mice entered spaces that made them uneasy and anxious. Optogenetics (a biological technique that uses light to control the cells) was used to manage these cells.

When the activity of these cells was reduced, mice seemed much more relaxed and less anxious. But when the activity of these cells paced up again, the mice got more frightened. The mice couldn’t go too far in the maze while under stress.

Conclusion

Anxiety disorders, permanent or episodic, are among the worst kinds of mental ailments. Researchers have long been working on exploring the most effective ways to treat it.

The cells that caused anxiety in mice is not an ideal measure of modulating anxiety in humans. A lot of the research is already going on. Let’s hope that the scientists identify exactly which brain cells are responsible for controlling anxiety.

Inspired by: Mental Floss

Special thanks to Amnah A. Fawad whose extensive study on the topic gave the article the right direction. 

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