Alcohol and its Affect on Alzheimer's.

I think it's safe to say that most people know about the negative effects of alcohol, it is after all a drug.  Chronic alcohol abuse can cause neuronal dysfunction and brain damage.  But how many people know about the positive effects?  Some might say, "but alcohol is a depressant! there can't be any positive effects."  Those people would be incorrect.  Studies show that those who consume low-moderate amounts of alcohol have a lesser chance of age-dependent cognitive decline and/or dementia, this includes Alzheimer's Disease, than those who abstain from alcohol.
A study done by Michael A. Collins and colleges states the previous, that low-moderate consumers of alcohol have a lesser chance of neurodegeneration.  The study found that moderate ethanol preconditioning prevented neurodegeneration due to β-amyloid .  β-amyloid is a peptide that has been found to be involved in causing Alzheimer's disease and is the main amyloid present in the brains of patients with Alzheimer's.
The Alzheimer's Drug Discovery Foundation posted an article in January of 2014 explaining this phenomenon.  According to the ADDF, low-moderate alcohol consumption means roughly 1 serving (15 grams of alcohol) for women and 2 servings for men.  Ethanol or ethyl alcohol is the chemical name for alcohol.  It should be noted that while it's being discussed that low-moderate consumption can help prevent Alzheimer's, heavy and excessive alcohol consumption can increase the chances of dementia.
Following the suggested amounts, 1 serving of alcohol equals roughly 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of 80-proof liquor.  This however is an average, older adults and those with smaller body mass index are more sensitive to alcohol.  While different types of alcohol will still give the same results, red wine has shown to be the most effective.  A study that the ADDF reported on involved 5000 adults who were tested regularly on learning, memory, and attention for 7 years.  Those that drank red wine performed better in every category and had slower age-related cognitive decline than those who drank other forms of alcohol.
The ADDF states that low-moderate amounts of alcohol are linked to a 50% decrease in the risk of having Alzheimer's.  One must keep in mind though that alcohol consumption is used to prevent the risk of Alzheimer's but does not aid in someone who already has it.  Most of the medications that Alzheimer's patients take can not be mixed with alcohol.
So why does this help?  Going back to the study by Collins, ethanol preconditioning was tested in rats, this essentially means ethanol (alcohol) was given to the rats.  The study showed that treatment with ethanol concentrations effectively preconditioned the rat brains to withstand dementia-associated proteins like the β-amyloid mentioned before.  Neuroprotective HSP is released due to the ethanol preconditioning and this helps protect the brain from dementia causing proteins.  Therefore, the right amount of alcohol can actually help to protect your brain and decrease the chances of neurodegeneration.



Links:
http://www.ncbi.nlm.nih.gov/pubmed/20422315  Collins' Study

http://www.alzdiscovery.org/cognitive-vitality/report/low-to-moderate-alcohol-consumption ADDF's page

Collins' Citation:

Collins, Michael A., Edward J. Neafsey, Kewei Wang, Nicholas J. Achille, Robert M. Mitchell, and Sreevidya Sivaswamy. "Moderate Ethanol Preconditioning of Rat Brain Cultures Engenders Neuroprotection Against Dementia-Inducing Neuroinflammatory Proteins: Possible Signaling Mechanisms." Molecular Neurobiology. U.S. National Library of Medicine, n.d. Web. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908405/>.

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"Nov 2015." Discover Magazine. N.p., n.d. Web. <http://discovermagazine.com/2015/march/16-cracking-the-alzheimers-code>.

Alleyne, Richard. "Red Wine 'can Protect against Radiation'" The Telegraph. Telegraph Media Group, n.d. Web.