Aspartame and Cognitive Function?

The fact that there is a "does" and there is a "does not" should be enough.

If you've ever read a scientific study, you will never see these conclusions.

You will see a "may" or "no indication that...".

Very true, and for that very reason, I should be more careful with my wording. Good call.

I'd be interested to see the one demonstrating the link between aspartame and serotonin. The hypothalamus/pituitary/thyroid control the production and regulation of hormones, right? So assuming that aspartame probably can't get into the brain, does that mean it messes up the thyroid?

Yes, hypothetically, if aspartame was acting directly on the hypothalamus/pituitary, then it would be crossing the blood-brain barrier.

However, there is a lot of cross-talk in the endocrine system, so (again hypothetically) aspartame could be acting somewhere in the periphery to stimulate the release of some other hormone which could cross the blood brain barrier and stimulate the hypothalamus and/or pituitary.

Alternatively, as you pointed out, it could act directly on the thyroid.

But I don't believe it does any of that. I've never seen any evidence to indicate that it does. I have not done an exhaustive search.

I did just take a second to go to Pubmed and search "aspartame + endocrine". I found the following (which isn't much):

http://www.ncbi.nlm.nih.gov/pubmed/7441091
J Environ Pathol Toxicol. 1980 Jun-Jul;3(5-6):363-73.
The biological properties of aspartame. III. Examination for endocrine-like activities.
Saunders FJ, Pautsch WF, Nutting EF.
Abstract
A series of studies with aspartame were run in mice, rats and rabbits using standard procedures to characterize possible estrogenic, androgenic, progestational and glucocorticoid activities. Aspartame was administered orally at levels (ca 300 mg/kg/day) substantially in excess of expected maximal human intake when used as a sweetening agent. No significant hormone-mimetic response was observed in the endocrine target organs evaluated. In similar studies, when administered simultaneously with the steroid hormones, it did not reduce the response expected with the steroid. Thus, it was concluded that ingestion of aspartame should not produce any estrogenic, androgenic, progestational or glucocorticoid-like effects. Further, it should not alter the actions of the endogeneous steroid hormones.


Cell Signal. 1998 Nov;10(10):727-33.
Effects of artificial sweeteners on insulin release and cationic fluxes in rat pancreatic islets.
Malaisse WJ, Vanonderbergen A, Louchami K, Jijakli H, Malaisse-Lagae F.
Source
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Abstract
Beta-L-glucose pentaacetate, but not alpha-D-galactose pentaacetate, was recently reported to taste bitter and to stimulate insulin release. This finding led, in the present study, to the investigation of the effects of both bitter and non-bitter artificial sweeteners on insulin release and cationic fluxes in isolated rat pancreatic islets. Sodium saccharin (1.0-10.0 mM), sodium cyclamate (5.0-10.0 mM), stevioside (1.0 mM) and acesulfame-K (1.0-15.0 mM), all of which display a bitter taste, augmented insulin release from islets incubated in the presence of 7.0 mM D-glucose. In contrast, aspartame (1.0-10.0 mM), which is devoid of bitter taste, failed to affect insulin secretion. A positive secretory response to acesulfame-K was still observed when the extracellular K+ concentration was adjusted to the same value as that in control media. No major changes in 86Rb and 45Ca outflow from pre-labelled perifused islets could be attributed to the saccharin, cyclamic or acesulfame anions. It is proposed that the insulinotropic action of some artificial sweeteners and, possibly, that of selected hexose pentaacetate esters may require G-protein-coupled receptors similar to those operative in the recognition of bitter compounds by taste buds.

"Aspartame + thyroid" produced nothing useful (3 articles, but none of them were about aspartame acting on the thyroid).

"Aspartame + hypothalmus" produced 11 articles... some did seem to suggest a effect of aspartame on rat brain, but as I've already discussed elsewhere, the rat blood-brain barrier seems to be less selective than the human blood-brain barrier when we're talking amino acids. Example: glutamate will cross the blood brain barrier in rats, but probably doesn't in humans.

There was also this little gem, which I liked (but it's not necessarily talking about a direct affect of aspartame on the brain):

Am J Clin Nutr. 2005 Nov;82(5):1011-6.
Functional magnetic resonance imaging of human hypothalamic responses to sweet taste and calories.
Smeets PA, de Graaf C, Stafleu A, van Osch MJ, van der Grond J.
Source
Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands. paul@isi.uu.nl
Abstract
BACKGROUND:
Evidence exists that beverages do not trigger appropriate anticipatory physiologic responses, such as cephalic phase insulin release. Therefore, it is of interest to elucidate the food properties necessary for triggering adaptive responses. Previously, we found a prolonged dose-dependent decrease in the hypothalamic functional magnetic resonance imaging signal after ingestion of a glucose solution.
OBJECTIVES:
The aims of the present study were to measure the effects of sweet taste and energy content on the hypothalamic response to glucose ingestion and to measure the concomitant changes in blood glucose and insulin concentrations.
DESIGN:
Five healthy, normal-weight men participated in a randomized crossover design trial. The subjects were scanned 4 times for 37 min on separate days with functional magnetic resonance imaging. After 7 min, they ingested 1 of the following 4 stimuli (300 mL of each): water (control), a glucose solution, an aspartame (sweet taste) solution, or a maltodextrin (nonsweet carbohydrate) solution.
RESULTS:
Glucose ingestion resulted in a prolonged and significant signal decrease in the upper hypothalamus (P < 0.05). Water, aspartame, and maltodextrin had no such effect. Glucose and maltodextrin ingestions resulted in similar increases in blood glucose and insulin concentrations. However, only glucose triggered an early rise in insulin concentrations. Aspartame did not trigger any insulin response.
CONCLUSIONS:
Our findings suggest that both sweet taste and energy content are required for a hypothalamic response. The combination of sweet taste and energy content could be crucial in triggering adaptive responses to sweetened beverages.

Anyway, you should really play around on PubMed. It's fun.

http://www.wnho.net/new_aspartame_studies.htm

http://www.holisticmed.com/aspartame/

Aspartame contains three very insidious components: methanol, phenylalanine, and aspartic acid. All three of these chemicals have each been shown to either stimulate brain cells to death, severely disrupt hormone balances in the brain or act as a dangerous nerve poison.

The following are a handful of quotes from an article entitled Aspartame: What You Don't Know Can Hurt You. We would definitely recommend that you read that whole article when you get a chance. Here are the quotes about how incredibly bad aspartame is for you.....

Aspartame accounts for over 75 percent of the adverse reactions to food additives reported to the FDA. Many of these reactions are very serious including seizures and death.

A few of the 90 different documented symptoms listed in the report as being caused by aspartame include: Headaches/migraines, dizziness, seizures, nausea, numbness, muscle spasms, weight gain, rashes, depression, fatigue, irritability, tachycardia, insomnia, vision problems, hearing loss, heart palpitations, breathing difficulties, anxiety attacks, slurred speech, loss of taste, tinnitus, vertigo, memory loss, and joint pain.

According to researchers and physicians studying the adverse effects of aspartame, the following chronic illnesses can be triggered or worsened by ingesting of aspartame: Brain tumors, multiple sclerosis, epilepsy, chronic fatigue syndrome, parkinson's disease, alzheimer's, mental retardation, lymphoma, birth defects, fibromyalgia, and diabetes.

As you can see, aspartame is no laughing matter.

And did you know that aspartame is 10 percent methanol?

Methanol (also known as wood alcohol) is a very deadly poison.

In fact, methanol poisoning has caused many alcoholics to end up blind or dead.

And did you know that once methanol breaks down inside the body one of the byproducts is formaldehyde?

Here is another quote from the article cited above.....

Methanol breaks down into formic acid and formaldehyde in the body. Formaldehyde is a deadly neurotoxin. An EPA assessment of methanol states that methanol "is considered a cumulative poison due to the low rate of excretion once it is absorbed. In the body, methanol is oxidized to formaldehyde and formic acid; both of these metabolites are toxic." They recommend a limit of consumption of 7.8 mg/day. A one-liter (approx. 1 quart) aspartame-sweetened beverage contains about 56 mg of methanol. Heavy users of aspartame-containing products consume as much as 250 mg of methanol daily or 32 times the EPA limit.

Yuck!

Taken From: http://organichealthadviser.com/archives/aspartame-dangers

I also read an article several years back about aspartame and the effects it can enhance cognitively, in the brain of a person with Multiple Sclerosis. I refuse to have anything with aspartame in it! I want to stay at the level of MS that I'm at, and hang on to the cognitive abilities I have

Aspartame contains three very insidious components: methanol, phenylalanine, and aspartic acid.

Oh good gravy. Phenylalanine and aspartic acid are amino acids found in every protein you eat. Your body is perfectly equipped to handle phenylalanine and aspartic acid. In fact, you actually use phenylalanine and aspartic acid as building blocks for muscles, enzymes, etc... Yes... that's right... you have phenylalanine and aspartic acid in every cell of your body right now. Any basic biology class should have taught you that.

Methanol? Also not a problem in small concentrations.

Aspartame & MS are a bad combo :sick:

Hello all- I had a girlfriend who had some neurological issues. When she stopped eating it, they stopped too. Sorry to be sketchy because I know there are some nay-sayers, but that was her experience. I have bad headaches from it. I also have bad headaches from Affrin but sometimes my allergies are so bad, it just has to be done.

The UK is doing another study due out in Sept 2012: http://www.foodsafetynews.com/2011/11/europe-re-evaluates-aspartame-safety/

Far more (real) evidence about the negative effects of a high sugar diet isn't there? I can't be expected to give up everything...

I have heard over and over and over again that aspartame is the devil. But I haven't seen a lot of research to back this up.

There isn't any.

Your right.
There is no scientific study indicating demonic roots to aspartame. (At least that I could find)
However there certainly has been studies which have concluded there should be concern over consumption of aspartame.