July 2016 Journal of Neurology
Hearing has long been the poor relation of memory and vision in the cognitive clinic. Hearing deficits associated with cognitive impairment have attracted much recent interest, motivated by emerging evidence that impaired hearing is a risk factor for cognitive decline. Interventions targeting auditory processes (most notably, music) have gained wide currency. However, the organisation of the human auditory brain is complex and incompletely understood. Moreover, neuropsychological frameworks for characterising hearing disorders produced by brain disease and practical tools for assessing auditory functions suitable for use in cognitively impaired patients are often lacking. There is a need to develop practical and reliable tests that can separate the effects of peripheral hearing and auditory cognitive dysfunction, to develop auditory interventions directed to cognitively impaired people and to assess these systematically and longitudinally in a range of dementias, referenced to healthy older people. In addition to capturing disability and improving quality of life, a more detailed picture of the spectrum of auditory dysfunction in dementia would have considerable neurobiological and clinical resonance. Sound is a dynamic and computationally demanding sensory signal that engages complex emotional and other behaviours: the processing of sounds taxes brain networks targeted by neurodegenerative pathologies and may yet yield novel cognitive ‘stress tests’ for diagnosis and treatment tracking in these diseases.