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A Case of the Re-Emergence of Panic and Anxiety Symptoms After Initiation of a High-Protein, Very Low Carbohydrate Diet

Key Words: dietary factors • panic disorder

TO THE EDITOR: Anxiety disorders are common and disabling. Many medical conditions and substances, including prescribed medications, precipitate anxiety symptoms,¹ but there are no reported cases of a high-protein, low-carbohydrate diet initiating or exacerbating anxiety symptoms. This report describes a woman with well-controlled panic disorder who developed a return of her panic symptoms, despite previously adequate treatment, after starting a high-protein, very low carbohydrate diet (the Atkins diet).

Case Report

Ms. A presented at the age of 37 with a 2-week history of daily episodes of increasing panic attacks consisting of lightheadedness, feeling "sick to her stomach," chest tightness, dizziness, and an overwhelming sense of fear without depression. These attacks had sudden onset and lasted for 30 to 45 minutes. An imminent vacation plan was a possible precipitant.

Past psychiatric history revealed that she had experienced similar attacks 4 years previously. She received an extensive medical work-up, including an echocardiogram, ECG, upper endoscopy, and blood work, with normal results. She had had 6 months of daily attacks, during which she severely restricted her trips outside her home. She was successfully treated with twice-weekly counseling for 3 months and alprazolam for 1 year. Ms. A had been off alprazolam for 2 years before the reemergence of symptoms. She had no history of psychiatric hospitalization or symptoms of psychosis, mania, posttraumatic stress disorder, obsessive-compulsive disorder, or alcohol or substance abuse. Medical history was noncontributory. She was on no medications.

The patient was treated with alprazolam, which was titrated to 1.0 mg qid, and sertraline 50 mg/day. Her panic attacks and phobic avoidance resolved completely. During the ensuing 10 years, the patient's panic disorder and agoraphobia remained well-controlled on alprazolam 1 mg qid and sertraline 50 mg–100 mg per day. She had only two full-blown panic attacks, rare limited-symptom attacks, and normal functioning.

At the age of 47, the patient decided to go on the Atkins diet. She weighed 252 pounds. She had struggled with her weight for most of her life and had failed at a variety of weight-loss regimens. One day after starting on the Atkins diet, the patient began to experience an internal sensation of "shakiness." This eventually progressed to a full-fledged panic attack later that day. She increased her sertraline dose to 100 mg to control these symptoms. She continued to have frequent panic attacks, and there was a marked increase in her baseline level of anxiety over the next 4 weeks.

She believed that her diet was connected to these symptoms, but did not stop the diet because she had lost 17 pounds. She ultimately decided to begin eating carbohydrates and quit the diet. Her symptoms improved that first day, and all symptoms were resolved after several days. She has continued to do well over the past few years.

Discussion

Both anxiety disorders and dieting are common in the United States and are more common in women. The lifetime prevalence for anxiety disorders and panic disorder are approximately 19.2% and 2%, respectively.² The point-prevalence of dieting among U.S. adults is 16.5%, with the highest prevalence being among white women (21.1%).³ Many diets involve severe restriction of carbohydrate intake. By some estimates, 25 million Americans are following the Atkins diet, and one-third of American adults restrict carbohydrates.⁴

Although there have been no case reports of a low-carbohydrate, high-protein diet inducing or exacerbating panic disorder, these diets have been linked to worsening of mood, increasing fatigue, dizziness, irritability, headaches, confusion, and sleep problems.^5–8 Dr. Atkins noted that his diet may cause fatigue, faintness, palpitations, headaches, and cold sweats during the first 3 days. He attributed these symptoms to withdrawal from foods to which the patient was addicted.⁹ Although there is some evidence that intermittent excessive sugar intake can cause endogenous opioid-dependence in rats,¹⁰ this phenomenon probably does not explain this patient's symptoms, since her symptoms lasted for 4 weeks.

Possible mechanisms by which the Atkins diet may worsen panic disorder include the induction of ketosis and the diet's effect on brain serotonin levels. The Atkins diet begins with a severe restriction of carbohydrate intake, which leads to the mobilization of the body's glycogen stores from liver and muscle cells and the development of ketosis. Ketosis can cause dehydration, which may lead to headaches, confusion, lethargy, weakness, dizziness, and irritability.^5,11

Short-term dieting reduces the plasma concentration of tryptophan, with a concomitant reduction in serotonin synthesis and release in the brain.¹² Carbohydrate consumption, but not protein consumption, increases serotonin release in the brain by increasing the ratio of tryptophan to other large, neutral amino acids in the blood.¹³ Therefore, it is likely that a low-carbohydrate diet would be especially likely to lower brain serotonin levels. Studies utilizing an experimental design resulting in short-term depletion of tryptophan have found an adverse effect on mood in patients with a history of depression, but mixed findings in worsening of panic disorder.^14,15 One study found that tryptophan depletion increased depression, anxiety, and somatic scores in SSRI-recovered and medicated depressed patients, as compared with the control condition.¹⁶

This patient's history demonstrated a marked temporal correlation between the beginning and ending of the Atkins diet with the relapse and resolution of her panic symptoms. The prevalence of dieting behavior in the population suggests the prudence of inquiring about changes in diet when a previously stable anxiety-disordered patient experiences a relapse.

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