Academic journal article Journal of Visual Impairment & Blindness

Theory of Mind and Cognitive Function in Adults with Alstrom or Usher Syndrome

Academic journal article Journal of Visual Impairment & Blindness

Theory of Mind and Cognitive Function in Adults with Alstrom or Usher Syndrome

Article excerpt

Usher syndrome type 2 (USH2) and Alstrom syndrome (AS) are two genetic conditions that cause the loss of hearing and vision (deafblindness). USH2 is the most common deafblind syndrome (3/ 100,000; Pennings, 2004; Sadeghi, 2005), and it accounts for more than 50% of all individuals 65 years or older with deaf-blindness. AS has a prevalence of less than one per million (Marshall, Beck, Maffei, & Naggert, 2007). The number of individuals with this syndrome is, however, rapidly increasing (900; 2015 Alstrom Syndrome International). USH2 and AS differ: USH2 affects the ear, eye, and (in some clinical types of the disease) the balance organs, whereas AS has a multisystemic pathology with a high incidence of additional multiple endocrine abnormalities, cardiomyopathy, pulmonary fibrosis, restrictive lung disease, and progressive hepatic and renal failure leading to reduced life expectancy (Marshall et al., 2007). AS features mild congenital sensory-neural hearing loss, which slowly develops over the first decade. It then generally progresses to moderate or severe hearing loss over the following decades. The severity of this hearing loss varies in AS, and the age of onset ranges from infancy to adolescence. The presence of otitis media is common, causing additive conductive loss. People with USH2, however, experience congenital, nonprogressive, moderate-to-severe hearing loss. Both AS and USH2 include retinitis pigmentosa (RP), a condition that deteriorates the rods and cones of the retina, leading to severe visual impairment. The type of RP associated with AS is much more aggressive, primarily affecting the cones with a faster progression, than that associated with USH2, which primarily affects the rods (Marshall et al., 2007; Sadeghi, Kimberling, Tranebjrnrg, & Moller, 2004). The onset of visual symptoms occurs earlier in AS than in USH2. In AS, vision declines during the first years of life, and RP causes complete blindness during adolescence. In USH2, the onset of visual symptoms occurs during mid-childhood, and the progression of loss of peripheral vision is typically slow. When the process stabilizes, a central visual field of approximately 10 degrees remains (Pennings, 2004). Most individuals (75%) with USH2 have residual vision in their fifties (Sadeghi et al., 2004). However, although a narrow visual field remains and the remaining visual acuity allows for some visual functioning, individuals with USH2 are extremely sensitive to light, and many experience poor contrast sensitivity.

Theory of mind (ToM) refers to the capacity to impute mental states to one's self and others; that is, it is the ability to understand the reasons for others' actions and feelings (Happe, 1994; Jolliffe & Baron-Cohen, 1999). ToM is a highly complex social-cognitive ability that depends on several other cognitive and social skills such as working memory (Davis & Pratt, 1995), executive function (Muller, Liebermann-Finestone, Carpendale, Hammond, & Bibok, 2012), central coherence, and language competency (Slade & Ruffman, 2005). The development of ToM is commonly delayed in individuals with either congenital severe-to-profound hearing loss (Peterson, 2004; Wellman, Fang, & Peterson, 2011) or congenital severe-to-total visual impairment (Green, Pring, & Swettenham, 2004; Minter, Hobson, & Bishop, 1998; Peterson, Peterson, & Webb, 2000).

The research on ToM often focuses on its development during childhood and adolescence; however, this ability continues to be refined over a lifetime (Wellman et al., 2011). Levitt (2005) and Lewis, Freeman, Kyriakidou, Maridaki-Kassotaki, and Berridge (1996) have shown that the development of ToM is highly dependent on the quality and quantity of the individual's social interactions. These researchers observed that both interaction with a variety of individuals in childhood and the establishment of peer relationships during childhood and adolescence are of great importance to the development of ToM. …

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