Loud or distracting levels of environmental noise may negatively affect cognitive functioning in patients with schizophrenia, suggests a new study in Schizophrenia Research.
“Although there was little evidence that schizophrenia patients are more affected by noise than their healthy counterparts, environmental noise worsened their pre-existing cognitive deficits, particularly in the verbal memory domain,” the researchers wrote. “Cognitive assessment of clinical groups on noisy wards may lead to over-estimation of cognitive deficits in domains that are sensitive to noise.”
Bernice Wright, PhD, of King’s College London in the United Kingdom, and colleagues compared the effects of noise on the cognitive performance of 18 patients with schizophrenia and 18 age- and sex-matched healthy adults. All participants had normal hearing and vision, an IQ of at least 80, and no history of a brain or substance abuse disorder. Under quiet, urban, and social noise conditions in a cognitive battery administered 1 to 2 weeks apart, the 36 participants took 7 tests assessing psychomotor speed, attention, executive functioning, working memory, and verbal learning and memory.
The quiet condition was no louder than 30 A-weighted decibles (dB[a]) in a sound-proof laboratory. The social noise condition included background unintelligible babble and footsteps in a crowded hall staying around 68 dB(A), plus occasional peaks of up to 78 db(A) of mixed social sounds. The urban noise included only building site noise without any social noise but with similar intensity and patterns to the social sounds.
Compared to the healthy participants, the patients with schizophrenia performed more poorly on psychomotor speed, attention, executive function, working memory, and verbal recall and recognition during all 3 noise conditions. Both groups of participants had worse working memory during social noises than during quiet conditions, but performance under social and urban noise conditions did not differ for either group. The schizophrenia patients also had delayed verbal recall and recognition relative to the control participants during the urban and social noise conditions.
“Despite a lack of significant differential effects of urban or social noise in the patient and healthy participant groups, this pilot study demonstrates that noisy situations may further alter seemingly stable cognitive deficits in people with schizophrenia,” the authors wrote. “Given the association between cognitive function and functional outcomes, noise management, such as reducing exposure to noise where feasible, may improve the lives of people with psychotic disorders.”
Wright B, Peters E, Ettinger U, Kuipers E, Kumari V. Effects of environmental noise on cognitive (dys)functions in schizophrenia: a pilot within-subjects experimental study. Schizophr Res. 2016; Mar 23. [Epub ahead of print]