Why does Alcohol make you tipsy?
Updated: Dec 13, 2018
Inherently, alcohol affects pretty much your entire brain - this is due to its depressive symptoms, which decreases the likelihood of neural firing (explained below).
Essentially, neurons have two major neurotransmitters - glutamate (excitatory), and gamma amino butyric acid a.k.a GABA (inhibitory). Alcohol alters the functioning of these two neurotransmitters to create an inhibitory effect.
Firstly, alcohol increases the release of GABA, making your neurons in the brain less likely to fire - inducing feelings of sleepiness and sluggishness. It achieves this by either promoting the release of GABA from the pre-synaptic neuron , by increasing the number of GABA receptors on the post-synaptic neuron, or by increasing the permeability of the inhibitory ion channels activated by GABA receptors via inducing conformational changes, thus raising the activity of GABA receptors. Why this occurs in terms of molecular interactions, I could not find any research on.
Nevertheless, this heightened inhibition in neurons throughout the brain contributes to the lethargy experienced upon alcohol consumption. This suppression, however, is notable in the amygdala - the brain region involved in regulating one’s emotional state, suggesting a reason for one’s increased emotional vulnerability during alcohol consumption.
Alcohol also blocks glutamate NMDA receptors by interfering with their activity. By lowering excitation, this can lead to uncontrolled movements and slurred speech. Moreover, since glutamate mediates memory, its inhibition is partly responsible for the ‘blackouts’ or loss of memory experienced upon alcohol intoxication. Again, NMDA blockage is notable in the amygdala, contributing to the rash and impulsive behaviors exhibited under the influence of alcohol.
The amygdala is located as shown in the image below:
Based on animal studies, such suppression was also found to occur in the hippocampus (responsible primarily for memory and spatial awareness), sensory regions, and hypothalamus (responsible for regulating metabolic functions and hormone release). However, the amygdala still remained the primary region affected. Research also found increased loss of Pukinje cells (play a role in movement/motor control) in the cerebrum, and suggested that this was higher when taken daily as opposed to binge consumption in rats. Moreover, mature neurons were more likely to undergo cell death.
Overall, there has been a loss of white matter (comprising mostly of neural axons) in alcoholics. In humans, neuronal loss was found in the cerebral cortex, cerebellum, and hypothalamus.
The locations of these regions are displayed in the image below.