Eating Disorder as a Psychiatric Onset of Juvenile Huntington's Disease

To the Editor: Huntington's disease is an autosomal-dominant disorder with onset in midlife caused by an excess of CAG nucleotide repeats in the IT15 gene, codifying for huntingtin protein, and is classically characterized by motor, cognitive, and psychiatric disturbances. Juvenile forms of Huntington's disease may have an atypical presentation with different motor signs including parkinsonism and ataxia and, commonly, with nonspecific psychiatric features. Among the broad spectrum of psychiatric symptoms, little attention has been paid to the possible association between Huntington's disease and eating disorders. We describe the case of a young woman with Huntington's disease that developed with an eating disorder.

Case Report

The patient's family history was unknown because she had been adopted at birth. After a family bereavement when she was 16 years old, the girl developed an eating disorder that was characterized by fear of weight gain, frequent binge eating, compensatory behaviors, and an abnormally low body weight without amenorrhea. An eating disorder not otherwise specified was diagnosed, and she was treated with cognitive-behavioral therapy. At age 22 she began to complain of instability and disequilibrium. She experienced progressively worsening falls until age 26, when she came to our attention. Neurological examination revealed moderately depressed mood and partial cooperation; mild choreic movements in the extremities, trunk, and face; rare distal myoclonus; reduced eye-head coordination; bilateral brisk reflexes; limb hypotonia and dysmetria; and ataxic gait and balance. Neuropsychological testing revealed a low IQ (WAIS score=52). A blood examination and MRI failed to show clear abnormalities. Genetic testing revealed a CAG expansion (large/short allele: 55/17 triplets) in the IT15 gene. Treatment with pimozide, 2 mg/day, moderately improved her mood.

Over the next 4 years, the patient's motor and cognitive profile progressively deteriorated, and frequent binge eating episodes reappeared.

Discussion

In our juvenile Huntington's disease patient, the eating disorder at onset preceded motor symptoms by 6 years. Although the two diseases may be a casual finding in our patient, there could be a link. Involvement of frontostriatal circuits and the hypothalamus has been reported in both diseases (1). Recent studies have focused on hypothalamic dysfunction in Huntington's disease, and hypothalamic atrophy was found in Huntington's disease patients by neuropathological analysis (2). MRI, positron emission tomography, and clinical data support a hypothalamic involvement in early Huntington's disease patients and premanifest Huntington's disease gene carriers (3). In addition, the hypothalamus plays a critical role in regulation of feeding and appetite. An alteration of hypothalamic-pituitary-adrenal axis function is known in eating disorders, and a recent functional MRI study disclosed an aberrant hypothalamic activation in eating disorder patients with binge-purge behaviors (1). Hypothalamic dysfunction could be related to the onset of eating disorders in our patient and to the reappearance of abnormal eating behavior.