Color discrimination in schizophrenia

The possible role of retinal dopaminergic system in visual performance

“…In the isoluminant blue-onyellow and high contrast achromatic conditions, there were no significant differences between the groups. This in contrast to Shuwairi et al (2002) who found general hue discrimination errors evaluated by five color discrimination measurements, in patients with schizophrenia, and also to evidence showing that other neuropsychiatric conditions that involve dopaminergic depletion (like PD and patients with cocaine withdrawal) were associated with color discrimination deficits along the blue-hue (tritan-wavelength-sensitive) axis. No significant differences were found between the three groups regarding luminance contrast threshold for achromatic dots.…”

“…Nevertheless, the results are consistent with Regan and Maxner (1987) and other authors' findings in PD, regarding the effect of impairment of the visual pathway leading from the retina to the occipital cortex via the magnocellular layer of the lateral geniculate body (rather than the parvocellular pathway) on visual processing dysfunctions, although the type of DA functioning impairment is different in this disease. However, the lack of DA medication might perhaps be related to the lack of effect on the isoluminant blue-on-yellow condition, since previous studies (Shuwairi et al, 2002) found a general hue discrimination deficits in medicated patients.…”

“…The findings of this review addressing visual dysfunction in color vision or discrimination places a challenge to this theoretical framework. Although the available data are not consistent in this respect and both normal and impaired color discrimination has been reported in PD, AD, GTS and untreated schizophrenic patients, a specific, shortwavelength (tritan, blue-yellow-axis), color discrimination impairment had been observed in many dopaminergic pathologies like PD Buttner et al, 2000;Haug et al, 1994), aging (Corbe et al, 1992;Jackson and Owsley, 2003), AD , cocainewithdrawal (Desai et al, 1997;Roy et al, 1997), and GTS (Melun et al, 2001), except for schizophrenic patients, in which hue discrimination was found, but no pattern emerged regarding a hue-specific axis of deficit (Phillipson and Harris, 1985;Shuwairi et al, 2002). The last study even suggested that DA excess may produce general dysfunction in color discrimination while DA deficiency, being the opposite condition, may produce hue-specific axis of deficit.…”

“…Color discrimination. Shuwairi et al (2002) investigating color vision in schizophrenic males (mean age 45.476.9 yr), compared their performance to that of control subjects, using five measures of color discrimination. Three tests (the City University, Farnsworth D-15, and Lanthony D-15) were relatively short and had minimal cognitive requirements.…”

Increased processing speed for emotionally negative odors in schizophrenia

“…In fact, a reduced P3 amplitude is one of the most robust ERP findings concerning schizophrenia (Jeon and Polich, 2003) and may reflect a reduced allocation of attentional resources. However, as the features of the P3 are mainly modality nonspecific, this effect does not point to an altered color perception, which seems to be normal in schizophrenia patients (Kopala et al, 1995;Shuwariri et al, 2002). Moreover, a reduced P3 amplitude is not disorderspecific, but is a robust finding also present in other disorders (e.g.…”