Alessandra Grasso

The prevalence of peripheral and central hearing impairment and its relation to cognition in older adults.

Age-related hearing loss (ARHL) and dementia are two highly prevalent conditions in the adult population. Recent studies have suggested that hearing loss is independently associated with poorer cognitive functioning. The aim of this study was to evaluate the prevalence of ARHL and cognitive impairment in a large sample of subjects older than 65 years and to correlate hearing function with cognitive function. A total of 488 subjects older than 65 years (mean age 72.8 years) participating in the Great Age Study underwent a complete audiological, neurological and neuropsychological evaluation as part of a multidisciplinary assessment. The prevalence of a hearing loss greater than 25 dB HL was 64.1%, of Central Auditory Processing Disorder (CAPD) was 14.3 and 25.3% of the subjects reported a hearing handicap as reported on the Hearing Handicap Inventory for the Elderly Screening Version questionnaire. Multiple logistic regression analysis corrected for gender, age and education duration showed that mild cognitive impairment (MCI) was significantly associated with hearing impairment (CAPD and hearing threshold; odds ratio 1.6, p = 0.05) and that Alzheimers disease (AD) was significantly associated with CAPD (odds ratio 4.2, p = 0.05). Given that up to 80% of patients affected by MCI convert to AD, adding auditory tests to a screening cognitive battery might have value in the early diagnosis of cognitive decline.

Midlife Metabolic Profile and the Risk of Late-Life Cognitive Decline

Among metabolic syndrome components, the effects of higher plasma glucose levels on cognitive decline (CD) have been considered in few studies. We evaluated the associations among midlife glycemia, total cholesterol, high-density lipoprotein cholesterol, triglycerides, midlife insulin resistance [homeostasis model assessment for insulin resistance (HOMA-index)], and CD in the older subjects of the population-based MICOL Study (Castellana Grotte, Italy) at baseline (M1) and at follow-ups seven (M2) and twenty years later (M3). At M1, a dementia risk score and a composite cardiovascular risk score for dementia were calculated. For 797 subjects out of 833, we obtained a Mini-Mental State Examination (MMSE) score at M3, subdividing these subjects in three cognitive functioning subgroups: normal cognition, mild CD, and moderate-severe CD. Mean fasting glycemia at baseline was significantly higher in moderate-severe CD subgroup (114.6±71.4 mg/dl) than in the normal cognition subgroup (101.2±20.6). Adjusting for gender, age, and other metabolic components, higher fasting glycemia values both at M1 [odds ratio (OR) = 1.31; 95% confidence interval (CI): 1.08-1.59] and M2 (OR = 1.26; 95% CI: 1.01-1.57) were associated with an increased risk of moderate-severe CD. Mean HOMA index value was significantly higher in the moderate-severe CD subgroup (5.7±9.4) compared to the normal cognition subgroup (2.9±1.4) at M1. The dementia risk probability (MMSE < 24) increased moving through higher categories of the dementia risk score and decreased as long as the cardiovascular score increased. The present findings highlighted the indication to control blood glucose levels, regardless of a diagnosis of diabetes mellitus, as early as midlife for prevention of late-life dementia.