First psychotic episode in an adult with Becker muscular dystrophy

In the present report, I describe the case of a 50-year-old male diagnosed with Becker muscular dystrophy (BMD) six years earlier, prior heart transplant and progressive motor impairment, treated with everolimus and mycophenolate mofetil, and no previous psychiatric history. The patient was admitted to a psychiatric emergency room with persecutory and prejudice delusions, as well as ideas of reference; these symptoms had worsened over the past months. Secondarily, he developed depressive mood, initial and intermediate insomnia, anorexia, passive death wishes, and decreased cognitive performance. He denied alcohol or recreational drug consumption. Both his brother and cousin had BMD and similar psychiatric symptoms.

No relevant changes had been detected on previous brain imaging. Laboratory and electrocardiographic evaluation assessment at admission again did not show changes. Pharmacological treatment with aripiprazole 10 mg, mirtazapine 30 mg and alprazolam 0.5 mg was started. A month later, a new evaluation showed significant improvement of psychotic symptoms.

To the best of my knowledge, this is the first report of new onset psychotic symptoms in a middle-aged adult with BMD. A previous report has described a 23-year-old male with BMD and psychosis,¹ however the early onset suggests a comorbid primary psychotic disorder. In the present case, the late onset of symptoms indicates a secondary condition resulting from BMD progression. Thus, the case highlights a possible common etiological link between BMD and psychiatric disorders.

BMD is an X-linked recessive inherited disorder caused by mutations in the dystrophin gene located at Xp21, resulting in the production of abnormal but functional dystrophin.²,³ This cytosolic protein stabilizes the plasma membrane of striated muscle cells in skeletal and cardiac muscle. Mutation of dystrophin causes progressive muscle wasting and weakness, with onset usually in childhood.³

There is evidence that BMD might be associated with mental disorders and mental retardation,³ possibly because dystrophin is also expressed in the cerebral cortex as part of the neuronal postsynaptic apparatus.² The discovery of a dystrophin brain isoform provides an organic basis for the association of BMD with psychiatric disorders.³ Cosegregation of BMD and schizophrenia has been suggested – as proposed by Zatz et al.,⁴ this could either be the result of a gene contributing to the mental disorder, linked to the dystrophin locus, or else caused by an abnormality in the expression of the dystrophin gene, directly affecting the brain.

An increased prevalence of depression among BMD patients has also been reported,³ confirmed by a recent study adding attention deficit hyperactivity disorder, autism spectrum disorder, obsessive-compulsive disorder, and bipolar disorder to the mental health concerns of individuals with dystrophinopathies.⁵ Some studies have also described a relation between cognitive impairment and dystrophin deficiencies, given the lack of dystrophin isoforms Dp71 and Dp140 in the brain of affected individuals during development.⁵

Considering the evidence of an association between BMD and psychiatric disorders, as illustrated by the present case, careful psychiatric and cognitive evaluation is essential in these patients, guiding diagnostic formulation and treatment planning and management. The literature on this subject is scarce, and thus further studies may contribute to a better characterization of psychopathology in individuals with BMD.

Acknowledgements

The author would like to express her gratitude to Dr. Filipa Senos Moutinho for her unwavering support and mentorship in every project, including the present paper, and to Dr. Gustavo Jesus for his willingness and precious help in reviewing this letter.

References

• ¹
  Abe M, Arai M, Maehara K, Arikawa E, Arahata K. [A case of Becker muscular dystrophy with schizophrenic symptoms]. No To Shinkei. 1990;42:1061-6.
• ²
  Chaichana KL, Buffington AL, Brandes M, Edwin D, Lee HB. Treatment of psychiatric comorbidities in a patient with becker muscular dystrophy. Psychosomatics. 2007;48:167-9.
• ³
  Melo M, Lauriano V, Gentil V, Eggers S, Del Bianco SS, Gimenez PR, et al. Becker and limb-girdle muscular dystrophies: a psychiatric and intellectual level comparative study. Am J Med Genet. 1995;60:33-8.
• ⁴
  Zatz M, Vallada H, Melo MS, Passos-Bueno MR, Vieira AH, Vainzof M, et al. Cosegregation of schizophrenia with Becker muscular dystrophy: susceptibility locus for schizophrenia at Xp21 or an effect of the dystrophin gene in the brain? J Med Genet. 1993;30:131-4.
• ⁵
  Imbornoni L, Price ET, Andrews J, Meaney FJ, Ciafaloni E, Cunniff C. Diagnostic and clinical characteristics of early-manifesting females with Duchenne or Becker muscular dystrophy. Am J Med Genet A. 2014;164A:2769-74.

Publication Dates

• Publication in this collection
  10 June 2019
• Date of issue
  May-Jun 2019

History

• Received
  22 Nov 2018
• Accepted
  2 Apr 2019