By H. J. Roberts, M.D., F.A.C.P., F.C.C.P.

Posted: 13 Feb 2005


Objectives: Clinical insights concerning a remediable cause of pseudotumor cerebri (benign intracranial hypertension) due to aspartame disease.

Materials and Methods: Observations of six women with pseudotumor cerebri who consumed considerable aspartame products, especially "diet" sodas.

Results: The ocular and other manifestations of aspartame disease disappeared or dramatically improved in all subjects after avoiding aspartame products, even obviating surgery.

Conclusions. Aspartame disease should be considered in patients presenting with pseudotumor cerebri, especially weight-conscious young women. The associated clinical features and underlying mechanisms are reviewed with emphasis on chronic methanol toxicity.

Aspartame disease caused by the use of products containing this chemical sweetener is a frequent but usually overlooked disorder. In the author's data base of persons so afflicted, six women developed pseudotumor cerebri (benign intracranial hypertension). This appears to be the first report of such an association.

The clinical and public health implications are significant. An estimated 70% of the United States adult population currently consumes aspartame products. The more common neurologic problems caused or aggravated by aspartame are noted in this discussion.


All six women were in their 20's and 30's. Preoccupied with their weight, they used considerable aspartame, chiefly as "diet" sodas. The representative case reports illustrate the extensive studies and treatments undertaken - ranging from repeated lumbar puncture for reducing cerebrospinal pressure to ventricular shunt procedures - prior to awareness of aspartame disease.

Representative Case Reports:

Case 1

A registered nurse with an extensive background in neurology and psychiatry was diagnosed as having pseudotumor cerebri in February 1997. intent upon losing weight, she began consuming considerable amounts of aspartame products. One month later, she suffered "fullness in my head, dizziness that wouldn't go away, impaired vision, panic attacks and a squishy feeling in my head." Several neurologic consultations and multiple studies ensued when severe headache developed.

The patient realized that the only significant change in her habits had been the use of aspartame products. She avoid them in April l997, with a progressive disappearance of symptoms. The repeat lumbar punctures being done in an attempt to decrease cerebrospinal fluid pressure were discontinued. Her "headache and strange feelings" would recur, however, if she drank an aspartame soda.

Case 2

The mother of two young children stated, "I used to drink aspartame by the hour." She was diagnosed as having pseudotumor cerebri by five neurologists.

This patient had experienced "floaters" and a large blind spot in the left eye. A neuro-ophthalmologist told her that she would become blind if a ventricular shunt was not performed to drain the excess cerebrospinal fluid causing pressure on the optic nerve. This was done in March, l998. Most of her symptoms persisted, however, especially severe headache, numbness of the feet and fingers, nausea and extreme fatigue.

Several persons, including her father-in-law supplied information about aspartame disease. She ignored it initially but then decided to stop aspartame products on a trial basis. "I saw major results. The headaches were not as bad, and the other symptoms did not bother me as much."


Each of these patients had been formally diagnosed by neurologists as having pseudotumor cerebri. Fortuitously, aspartame disease was considered thereafter by relatives or friends who had heard about aspartame disease, leading to aspartame abstinence.

Discussing pseudotumor cerebri in a previous text, the author noted "the greatest frequency of this disease among women under the age of thirty." Wilson and Gardner similarly emphasized the association of obesity and pseudotumor cerebri. forty-eight of their 61 cases were characterized as "fat young women."

The importance of considering aspartame disease under these circumstances is obvious. The patients usually have a good prognosis, and can be spared much anxiety and formidable medical or surgical interventions if this condition is recognized.

The diagnosis of pseudotumor cerebri was based on evidence for increased intracranial pressure, and the absence of infection, a mass lesion (brain tumor), obstruction of the ventricular system, and focal neurologic signs. The most prominent features were headache, papilledema and other ocular abnormalities (decreased vision, visual field loss; extraocular palsies).

The following considerations are germane:

Other Neurologic Aspects of Aspartame Disease

Aspartame and its metabolites are neurotoxic, based on extensive observations and corporate-neural research over 15 years. Women are afflicted with clinical aspartame disease three times more often than men in the data bases of both the author and the FDA. The diagnostic criteria appear in previous reports.

The following neurologic manifestations occurred among the initial 1200 aspartame reactors in the author's series. They included patients personally attended and persons providing detailed reports in a 9 page questionnaire.

Headache 518 (43%)
Dizziness, unsteadiness, or both 376 (31%)
Confusion, memory loss, or both 376 (31%)
Severe drowsiness and sleepless 150 (13%)
Convulsions (grand mal epileptic attacks) 129 (11%)
Petit mal attacks and "absences" 96 (3%)
Severe slurring of speech 124 (10%)
Severe tremors 101 (8%)
Severe "hyperactivity" and "restless legs" 78 (6%)
Atypical facial pain 70 (6%)

The foregoing complaints usually improved following aspartame avoidance and promptly recurred after resuming aspartame products, knowingly or inadvertently. Some examples:

The suspected causative or aggravating role of aspartame in human brain cancer also warrants mention in this context.

Mechanisms of Aspartame Neurotoxicity

Each of the components of aspartame - phenylalanine (50%); aspartic acid (40%); and methyl ester (10%) that promptly becomes free methyl alcohol (methanol) after ingestion - and their multiple breakdown products after exposure to heat or during storage are potentially neurotoxic. The mechanisms may variously involve dopamine (derived from phenylalanine), cerebral cholecystokinin (CCK), serotonin, endorphins, other important neurotransmitters, neuroglucopenia, the unique permeability of the blood brain barrier to phenylalanine, and the "aging" effect of the steroisomer D-aspartic acid. Others include methanol-induced cerebral edema and fluid disturbances noted in humans and experimentally.

The severe neurotoxic effects from chronic intake of free methanol are pertinent. Dr. Herbert S. Posner (National Institute of Environmental Health Sciences) wrote a review titled, "Biohazards of Methanol in Proposed New Uses," six years before FDA approval of aspartame. He emphasized failure to recognized the "delayed and irreversible effects on the nervous system of widely varying levels of exposure and at rather low levels."

The intake of methyl alcohol from natural sources is less than 10 mg. daily. Aspartame beverages average 55 mg. methanol per liter, but nearly twice as much in some sodas. Accordingly, individuals who drink five liters a day could ingest over 400 mg. methanol.

Several aspects of chronic methanol intake are listed:

Other studies clarify the chronic toxicity of aspartame-derived formaldehyde. The highly reactive formaldehyde molecules become bound to proteins and nucleic acids. The adducts formed are difficult to eliminate through usual metabolic pathways. Using adult male rats given oral aspartame C-labeled in the methanol carbon, Trocho et al convincingly demonstrated that formaldehyde derived from dietary aspartame binds to tissue components in vivo. Most of the radioactivity was bound to protein in plasma and liver, and had a long half life. It also was detected in brain, cornea, and retina. Furthermore, progressive accumulation of more label could be demonstrated when non-labeled aspartame was given over ten days, suggesting that aspartame-derived formaldehyde adducts are cumulative in tissue proteins and nucleic acids. These investigators commented, "The cumulative effects derived from the incorporation of label in the chronic administration model suggest that regular intake of aspartame may result in the progressive accumulation of formaldehyde adducts. It may be further speculated that the formation of adducts can help to explain the chronic effects of aspartame consumption on sensitive tissues such as brain."


Case histories of two additional women in their thirties with aspartame disease and pseudotumor cerebri have been received.


H. J. Roberts, M.D., FACP
6708 Pamela Lane
West Palm Beach, Florida 33405 USA


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