Usher syndrome develops as a result of genetic mutation inherited in an autosomal recessive manner (Yan & Liu, 2010). It is observed that mutative transformations in a set of genes can provoke the development of two major pathology components: sensorineural hearing loss determined by the structural damages in the inner ear, auditory nerve or CNS areas responsible for auditory analysis; and retinitis pigmentosa associated with degeneration of the retina caused by photoreceptor and pigment epithelium abnormalities leading to loss of vision (Domanico et al., 2012). Other clinical presentations include vestibular areflexia and psycho-emotional problems such as psychosis, atypical autism, schizophrenia, and others.
Usher syndrome affects approximately three to ten individuals out of 100 000 people around the world (Rijavec & Grubic, 2009). The syndrome can be found in about 8% of all patients with retinitis pigmentosa (Retina Australia NSW, n.d). The disorder equally affects both females and males. It is also observed that types I and II of the syndrome are the most widespread in the patient population.
Nowadays, researchers distinguish three major types of Usher syndrome depending on the peculiarities of the clinical presentation. Type I is characterized by a substantial congenital deafness, early-onset retinitis pigmentosa, and vestibular dysfunction (children learn to walk at the age of 18 months) (Yan & Liu, 2010). Type II is associated with non-progressive hearing loss, preservation of normal vestibular function and the onset of retinal degeneration after 10-20 years (Yan & Liu, 2010). Type III is manifested at the age of 11-13, proceeds with the worsening of blindness and deafness, and, in 50% of cases, is followed by vestibular disorders (Yan & Liu, 2010).
Congenital deafness and blindness are associated with multiple comorbid psycho-emotional conditions. There are a few explanations for a high incidence of psychological and behavioral problems among patients with the syndrome of all ages in the recent literature. First of all, they can occur as a result of a severe distress provoked by the progressive loss of vision because it was observed that various psycho-emotional problems occurred simultaneously with the loss of vision (Dammeyer, 2012). Secondly, these comorbid conditions can be stimulated by the communicative difficulties (Dammeyer, 2012).
The case study by Rais (2006) provides evidence for the reactive manner of psychosis development in the case of a 19-year-old patient. The researcher observes that the psychiatric symptoms including severe anxiety and fearfulness, inappropriate laughing, auditory hallucinations, disorientation, paranoia, etc. developed in parallel with the aggravation of his visual impairment. Since the age of 12 when the patient in the case was first diagnosed with Usher syndrome, the psychotic features developed in a gradual manner and it is possible to say that their occurrence was mediated via the feeling of isolation from the world and perceptions of the environment as hostile (Rais, 2006).
The similar observations were made in the case study by Hen-Ying and Chih-Chiang (2006). The researchers studied the cases of two family members with Usher syndrome type II. A vision degradation in the female patient has begun at the age of 16, and as her functional impairment deteriorated by the age of 24, she started to show the signs of psychosis and schizophrenia-like behavior: self-talking, shouting, visual, and auditory hallucinations, etc. In this way, the aggressive behavior in her case was associated with the function deterioration which interfered with her ability to work, communicate in a meaningful manner, and perform simple daily tasks. The brother of the patient had an early developed nearly complete deafness and also suffered from a gradual loss of vision since he was 15 (Hen-Ying & Chih-Chiang, 2006). However, he started to demonstrate destructive and disturbing behavior at the age of 17. It is possible to presume that the speed of comorbid psychiatric conditions’ development in the two cases depended on the severity of the patients’ impairments. However, Hen-Ying and Chih-Chiang (2006), emphasize that the etiology of the psychotic features represented in Usher syndrome is unclear.
The statistical data demonstrates that psychotic symptoms are present in 26 of 114 patients, and about 23% of individuals with Usher syndrome have various mental and behavioral conditions including schizophrenia, mental retardation, autism, and conduct disorder (Domanico et al., 2012). In the recent Denmark-based study of a sample comprised of 26 children (0-17 years old) with Usher syndrome, six participants (23%) showed the symptoms of various psychological and behavioral problems (Dammeyer, 2012). The identified conditions included schizophrenia, severe and mild retardation, atypical autism, conduct disorder, and eating disorders. Additionally, the researcher noticed that approximately one-third of the young patients without psycho-emotional disorders experience various psychosocial difficulties (Dammeyer, 2012). These difficulties may include depression, anxiety, and distress.
The occurrence of psychological conditions in patients can also be explained by the genetic factor. For instance, it is suggested that genes involved in the development of the syndrome are present on chromosomes 1,8, and 14 whereas chromosomes 8 and 14 are also implicated in the progression of bipolar disorder (Domanico et al., 2015). The recent research evidence also suggests that people with Usher syndrome may be genetically predisposed to the development of schizophrenia as risks for the occurrence of the both disorders increase if one of the family members have either of them (Dammeyer, 2012). Other potential causes may include different brain and neurologic abnormalities. For instance, the evidence provided by Hen-Ying and Chih-Chiang (2006) supports the suggestion that the disease process in Usher syndrome is not limited merely by auditory and visual systems but affect the entire brain because the examinations revealed the size of patients’ brain and cerebellum were abnormal.
The cognitive, social, and psycho-emotional development of people with Usher syndrome may be significantly impeded by hearing, vision, and balance impairments. As a result of the disability, patients undergo multiple psychological difficulties which can also be correlated with the occurrence of psychiatric conditions including psychosis, distress, schizophrenia, and so on. The data retrieved from the literature makes it clear that the incidence of the syndrome-related mental illnesses is somewhat similar in all age groups. However, in the majority of the analyzed cases, psychotic symptoms developed in individuals during adolescence or early adulthood with the progression of vision impairments and deterioration of function. Therefore, it is possible to assume that the severity of patients’ psychological conditions may largely depend on the type of disease and the combination of their impairments.
Some researchers emphasize the genetic nature of psychotic symptoms in individuals with the syndrome, while others regard them as reactions to the vision and hearing loss. Nevertheless, based on the literature review findings, it is possible to conclude that etiopathogenesis of the syndrome-related psycho-emotional conditions is multifactorial. The factors contributing to their development include environmental stimuli (e.g., isolation, and deprivation), genes, and different stress-provoked disorders.
Dammeyer, J. (2012). Children with Usher syndrome: mental and behavioral disorders. Behavioral and Brain Functions, 8(1), 16. doi:10.1186/1744-9081-8-16
Domanico, D., Fragiotta, S., Cutini, A., Grenga, P. L., & Vingolo, E. M. (2015). Psychosis, mood and behavioral disorders in Usher syndrome: Review of the literature. Medical Hypothesis, Discovery and Innovation in Ophthalmology, 4(2), 50–55.
Domanico, D., Fragiotta, S., Trabucco, P., Nebbioso, M., & Vingolo, E. M. (2012). Genetic analysis for two Italian siblings with Usher syndrome and schizophrenia. Case Reports in Ophthalmological Medicine, 2012, 1-6. Web.
Hen-Ying, W., & Chih-Chiang, C. (2006). Usher syndrome with psychotic symptoms: Two cases in the same family. Psychiatry & Clinical Neurosciences, 60(5), 626-628. Web.
Rais, D. (2006). Acute psychosis with paranoid features in a young patient with Usher’s syndrome: A case report. Priory Medical Journals, September.
Retina Australia NSW. (n.d.). Usher syndrome: Symptoms and causes. Web.
Rijavec, N., & Grubic, V. N. (2009). Usher syndrome and psychiatric symptoms: A challenge in psychiatric management. Psychiatria Danubina, 21(1), 68–71.
Yan, D., & Liu, X. Z. (2010). Genetics and pathological mechanisms of Usher syndrome. Journal of Human Genetics, 55(6), 327–335. Web.