Auditory Agnosia for Environmental Sounds in Alzheimer's Disease: Not Hearing and Not Listening?

Auditory agnosia for environmental sounds (AES) is an example of central auditory dysfunction. It is presumed to be independent of language deficits and in presence of normal hearing. We undertook a detailed neuropsychological assessment including environmental sound naming and recognition in 34 clinically mild Alzheimer's disease (AD) patients and 29 age-matched healthy control subjects. In patients with AD, audiometry was performed to assess the impact on test performance, and in normal controls the Hearing Handicap Inventory for the Elderly - Screening Version to exclude more than mild hearing loss. We adapted a validated environmental sound battery and found near perfect scores in controls. We found that environmental sound agnosia is common in mild AD. We found a statistically significant difference in mean pure tone audiometry in the best ear between patients with and those patients without naming deficits of 11.3 dB (p = 0.010) and of 14.7 dB (p = 0.000) between those with and without recognition deficits. Statistical significance remained after correcting for age, aphasia, Mini-Mental State Examination score, and working memory. Slight and moderate peripheral hearing loss increases the odds ratio of recognition deficits by 13.75 (confidence interval 2.3-81.5) compared to normal hearing patients. We did not find evidence for different forms of AES. This work suggests that an interaction between peripheral hearing loss and AD pathology produces problems with environmental sound recognition. It confirms that the relationship between hearing and dementia is complex but also suggests that interventions to prevent and treat hearing loss could have an effect on AD in its clinical expression.

Musical hallucinations: review of treatment effects.

BACKGROUND: Despite an increased scientific interest in musical hallucinations over the past 25 years, treatment protocols are still lacking. This may well be due to the fact that musical hallucinations have multiple causes, and that published cases are relatively rare. OBJECTIVE: To review the effects of published treatment methods for musical hallucinations. METHODS: A literature search yielded 175 articles discussing a total number of 516 cases, of which 147 articles discussed treatment in 276 individuals. We analyzed the treatment results in relation to the etiological factor considered responsible for the mediation of the musical hallucinations, i.e., idiopathic/hypoacusis, psychiatric disorder, brain lesion, and other pathology, epilepsy or intoxication/pharmacology. RESULTS: Musical hallucinations can disappear without intervention. When hallucinations are bearable, patients can be reassured without any other treatment. However, in other patients musical hallucinations are so disturbing that treatment is indicated. Distinct etiological groups appear to respond differently to treatment. In the hypoacusis group, treating the hearing impairment can yield significant improvement and coping strategies (e.g., more acoustic stimulation) are frequently helpful. Pharmacological treatment methods can also be successful, with antidepressants being possibly more helpful than antiepileptics (which are still better than antipsychotics). The limited use of acetylcholinesterase inhibitors has looked promising. Musical hallucinations occurring as part of a psychiatric disorder tend to respond well to psychopharmacological treatments targeting the underlying disorder. Musical hallucinations experienced in the context of brain injuries and epilepsy tend to respond well to antiepileptics, but their natural course is often benign, irrespective of any pharmacological treatment. When intoxication/pharmacology is the main etiological factor, it is important to stop or switch the causative substance or medication. CONCLUSION: Treatments for musical hallucinations tend to yield favorable results when they target the main etiological factor of these phenomena. There is a need to establish the natural course of musical hallucinations, their response to non-pharmacological treatments, and their effects on the patient's quality of life. There is also a need to standardize the assessment of treatment responses, and document long-term follow up.