Effects of Metabolic Syndrome on Language Functions in Aging

Abstract

This study explored effects of the metabolic syndrome (MetS) on language in aging. MetS is a constellation of five vascular and metabolic risk factors associated with the development of chronic diseases and increased risk of mortality, as well as brain and cognitive impairments. We tested 281 English-speaking older adults aged 55-84, free of stroke and dementia. Presence of MetS was based on the harmonized criteria (Alberti et al., 2009). Language performance was assessed by measures of accuracy and reaction time on two tasks of lexical retrieval and two tasks of sentence processing. Regression analyses, adjusted for age, education, gender, diabetes, hypertension, and heart disease, demonstrated that participants with MetS had significantly lower accuracy on measures of lexical retrieval (action naming) and sentence processing (embedded sentences, both subject and object relative clauses). Reaction time was slightly faster on the test of embedded sentences among those with MetS. MetS adversely affects the language performance of older adults, impairing accuracy of both lexical retrieval and sentence processing. This finding reinforces and extends results of earlier research documenting the negative influence of potentially treatable medical conditions (diabetes, hypertension) on language performance in aging. The unanticipated finding that persons with MetS were faster in processing embedded sentences may represent an impairment of timing functions among older individuals with MetS.

Demographic factors and retrieval of object and proper names after age 70

“…The results are also in line with reports that education is related to naming performance [ 9 ], and that individuals with higher education decline less steeply than are individuals with lower education on at least some cognitive tasks [ 12 ]. Moreover, our results replicate previous findings that demonstrated associations between health status and naming scores [ 10 ].…”

“…While self-rated health is a good predictor of mortality [ 17 ], it could be too general to incur a differential effect on each of the naming tasks studied here. Although changes in naming in healthy older adults might be related to risk factors for brain damage [ 9 , 10 ], there is no reason to assume that these risk factors lead to specific lesions that cause difficulties in one type of stimuli but not the other.…”

“…There is also preliminary evidence that specific health status affects naming in cognitively-intact individuals. Thus, presence of hypertension, but not diabetes, has been shown to associate with reduced naming, and presence of metabolic disease has been shown to associate with reduced action naming but not with reduced object naming [ 9 , 10 ].…”

Association of obesity, diabetes and hypertension with cognitive impairment in older age

“…As we adjusted for 3 of 4 components of the metabolic syndrome (all except dyslipidemia), it follows that obesity might be one driving force behind the cognitive impairment seen in people with the metabolic syndrome. 8 – 13 Mediation of the obesity-cognition association by presence of diabetes or hypertension is unlikely, as controlling for mediating factors would have led to a profound reduction in effect size. However, the possibility of an influence of subclinical insulin resistance or subclinical elevated blood pressure remains.…”

“… 6 It has been estimated that 22% of people aged over 70 years in the USA are currently cognitively impaired, 7 and epidemiological studies have frequently demonstrated associations with the metabolic syndrome. 8 – 13 Diabetes, hypertension and obesity together contribute to the diagnostic criteria of the metabolic syndrome 14 and have each been assessed in detail for their relationship with cognitive outcome. Links of diabetes to presence and risk of future cognitive impairment are well established, 15 , 16 while the evidence is less clear for obesity and hypertension.…”