There is more and more evidence that has found a link between depression and Alzheimer’s disease.
One of the probable suspects is the fact that low norepinephrine or low serotonin is often found with depression and more recent research has identified the impact these two brain chemicals have on Alzheimer’s.
Beta-amyloid (a peptide or small protein particle) has long been implicated in the development of Alzheimer’s disease and is recently being understood in more detail as to how it affects plaque formation in the brain, which is considered one of the hallmarks of Alzheimer’s. It also is being studied for its role in destroying the synapses, or connections between our nerve cells. If these synapses are destroyed, the instructions and information being relayed between the cells is also destroyed, leading to memory loss among other things.
Research is increasingly looking at the role that anti-depressants may play in affecting beta-amyloid, among other things. The exciting outcome of this research suggest that by increasing serotonin and norepinephrine levels, if they are clinically low, we may see improvement and perhaps a slowing down of Alzheimer’s progression.
Will these drugs help or hinder progression of Alzheimer’s down the road?
A 2014 study in The Science Translational Medicine Journal (American Association for the Advancement of Science) found that an increase in serotonin signaling resulted in a decrease of beta-amyloid in Alzheimer’s disease, both in vitro as well as in animal models. Specifically, when the SSRI, or selective serotonin reuptake inhibitor drug Citalopram (Brand name: Celexa) was given, previous plaques were halted from progressing and new plaque development was decreased by 78%.
A study by Current Alzheimer Research (2014) discovered that another SSRI, Fluoxetine (brand name: Prozac) resulted in “improved spatial memory, learning and emotional behaviors” of Alzheimer’s disease mice models.
Another study by Neurobiology of Aging (2014) found that norepinephrine, another chemical that is targeted with SNRI antidepressants, is neuroprotective and resulted in decreasing beta-amyloid neurotoxicity.
Lastly, a 2015 study by the Journal of Alzheimer’s Disease also found that norepinephrine protects against the neurotoxicity of beta-amyloid in animal studies. They discovered that removing the part of the brainstem that is the source of norepinephrine led to worsening Alzheimer’s symptoms and that increasing norepinephrine helped to improve the symptoms.
So what does all of this mean and why is a naturopath talking so much about antidepressants? The take home message is to understand the importance of healthy, balanced neurotransmitters (or brain chemicals) and how they relate not only to our current mood, but how they can also help or hinder progression of Alzheimer’s down the road. Blood tests and/or urine tests can help to determine whether your levels of serotonin and norepinephrine are ideal or not.
For those who are not on anti-depressants, but who may need to increase their levels, there are natural ways to increase norepinephrine. A couple of key supplements which increase norepinephrine (by decreasing oxidative stress) are n-acetyl cysteine (NAC) and glutathione. The Neurobiology of Aging (2014) article referred to earlier, found that “n-acetyl cysteine and glutathione…mimicked the protective effects of norepinephrine”. There are also other supplements such as 5 HTP (5 hydroxytryptophan) which can help as a precursor for serotonin.
Other than supplements, we can also use food to increase levels of the precursors to these chemicals. Tryptophan (found in fish, meat, eggs, cottage cheese, nuts, artichokes, avocados, kale, spinach, etc.) is one of the precursors to serotonin, and tyrosine (found in seaweed, soy, fish, poultry, eggs, mustard greens, etc.) is a precursor to norepinephrine.
Exercise also increases serotonin and norepinephrine naturally, and walking outside on a sunny day is the best of both worlds. Research suggest that 30 minutes a day or regulated exercise/ activity helps both in the moment as well as having some lasting effects.
As always, it is important to make sure you are under the care of a health professional before embarking on adding supplements to your diet. With serotonin and norepinephrine, as well as its precursors, there is such a thing as “ too much of a good thing” and elevated levels can lead to serotonin syndrome or there can be side effects between the supplements and medications, for example. Always check with your health care worker before starting any new regime.
Alison O’Brien-Moran is a naturopathic doctor working in Toronto, focusing on family health with a special interest in Alzheimer’s and cognitive health. She can be reached at ndfamilycare@gmail.com and 416-840-0721.