As I understand it, the effect of alcohol is simply due to dehydration of the brain tissue, effecting the efficiency of neuronal conduction and neurotransmitter diffusion.  Ethanol is structurally similar to water in many ways, and the hydroxyl (OH) group can intercolate itself into many of the places where a water molecule would be found, both in free solution, and as part of the structural hydration shells which are part of what gives many proteins their functional shape.  As the concentration of ethanol increases, more water is displaced, and each protein in the brain is stressed a little by this new environment.   There is also a change in the osmotic potential of the environment, which cells and neurones especially rely on to function.

Many of the symptoms of drunkenness can be seen in severe dehydration.  The effect is of an overall global derangement of brain function, rather than a specific targetted effect on a single neurotransmitter or cell type, as you would find with neurotropic drugs.

(edit) just to add the dehyrdation effect could conceivably be be enough of an effect to increase the incidence of red blood cell agglutination, to the point of slowing circulation in the peripheral capillaries (not stopping it) so there could be an element of truth in the observation, though I've never seen any credible report of this.

I got really interested and found one of the original scientific articles from Annals of the New York Academy of Sciences (1973) about alcohol causing red cell agglutination and inability of red cells going through smallest capillaries. downloaded full paper it and it makes fascinating reading:

http://www3.interscience.wiley.com/journal/119675932/abstract

 This link des not seem to work -I found the article in Wiley online library:

Annals of the New York Academy of SciencesVolume 215, Alcoholism and the Central Nervous System pages 356–365, April 1973

EXPERIMENTS AIMED AT SEPARATING THE MECHANICAL CIRCULATORY EFFECTS OF ETHANOL FROM SPECIFIC CHEMICAL EFFECTS

 An Introduction to a Biophysical Analysis of a Toxic State†

1. Raymond C. Pennington,
2. Melvin H. Knisely

Basically article says that red cell start clamping at very low doses of alcohol. They studied human blood in vitro at alcohol at 3g/l e.g. around total of 13 g of alhogol per human's 4l of blood - this is 1.3 units!.The authors Dr.Knisely et al directly say: (quote):

"In one study in 30 human adults (13 females, 17 males), microscopic observations were made of blood flow and the conditions of the small vessels in the conjuctiva, at the same time a blood sample was taken for determination of blood ethyl alcohol concentration. Ethanol concentrations ranged from zero to 328 mg/100ml. With increasing concentrations of alcohol in the blood, the size of aggreagated or agglutinated blood cell masses increased and the forward rates of flow in small vessels decreased correspondingly. With the higher concentrations of blood alcohol and the more severe reduction in forward flow rates, the number of vessels in statsis, plugged, occluded, and with no flow increased significantly. Plugged small vessels often ruptured. Within the extreme upper concentration of ethanol (225 and 328 mg/100ml blood), some small vessels were ruptured, producing microscopic hemorrhages into contiguous bulbar conjuctival tissue.

In maximual good health, the blood of huiman beings as well as animals is completely (!) unagglutinated"

<End of quote.>

Actually it appears to be a quote from Moskow, H.A, R.C.Pennigton & M.H.Knisely.1968,Alcohol, sludge and hypoxic areas of nervous system, liver and heart. Microvascular Res 1:174. doi:10.1016/0026-2862(68)90016-2

Athours also refer to great similarity of drunkedness caused by going up on a ballon etc: (quote)

"as occurs in climbing high mountains, balloon ascensions... and the effect of ingestion of alcoholic beverages.The hypoxic anoxia ... so produced initiates many of the symptoms and signs of being drunk..." (!)

I guess that  clamps of red cells have no way entering smallest capillaries (which only allow one red cell at a time, I understand). And as each neuron is fed by one of these smallest size capillaries then it follows that less or none red cells are able to get through to neurons in your brain!

No more drinking for me if 1.3 units are capable of almost suffocating neurons in my brain! And I am serious!

Here we are - some red blood cells agglutinations images attached:

 3 images of red cells - compare yourself:

1)Slight amounts of alcohol in the blood.

2)Very drunk person.

3)Sober person.