Abstract
Both cognitive function and striatal dopamine function decline by normal aging. However, the relationship among these three factors remains unclear. The aim of this study was to elucidate the association among age-related changes in the striatal dopamine transporter (DAT) and cognitive function in healthy subjects. The 30 healthy volunteers were enrolled in this research, the age ranged from 41 to 82 (64.5 ± 11.5, mean ± SD). All subjects were scanned with both T1-weighted magnetic resonance imaging (MRI) and 123I-FP-CIT single-photon emission computed tomography (SPECT) images. The Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) was used to evaluate cognitive function. Six spherical regions of interest (ROI) using 10 mm in diameter on the caudate nucleus, anterior putamen and posterior putamen were manually drawn on MRI image which was applied onto SPECT image. The relationship between striatal occipital ratio (SOR) values and WAIS-III subscore were analyzed by multiple regression analysis. Subscores which was significant were further analyzed by path analyses. Full intelligence quotient (IQ), verbal IQ, verbal comprehension were all positively correlated with age-adjusted striatal DAT binding (P < 0.01). Multiple regression analyses revealed that the coding digit symbol correlated with all striatal regions except for the left caudate (P < 0.04). Picture completion and right caudate, similarities and left caudate also showed a positive correlation (P < 0.04). Path analysis found that the right caudate and picture completion; the left caudate and similarities were correlated independently from age, whereas the models of coding digit symbol were not significant. These results suggest that age-based individual diversity of striatal DAT binding was associated with verbal function, and the caudate nucleus plays an important role in this association.
Highlights
In human cognitive performance peaks around age 20, and subsequently, as people age, a wide range of cognitive tasks exhibit a steady and accelerated decline (Salthouse, 2010)
Twelve healthy subjects underwent dopamine transporter (DAT) positron emission tomography and several cognitive batteries; the results showed that episodic memory and executive function were associated with striatal DAT binding and that both cognitive batteries declined with aging (Erixon-Lindroth et al, 2005)
The aim of this study was to clarify the relationship between the striatal DAT function, evaluated by [123I]FP-CIT singlephoton emission computed tomography (SPECT), and cognitive function measured by a standardized neuropsychological test, the Wechsler Adult Intelligence Scale (WAIS)-III, in healthy subjects
Summary
In human cognitive performance peaks around age 20, and subsequently, as people age, a wide range of cognitive tasks exhibit a steady and accelerated decline (Salthouse, 2010). Cognitive functions that decline with normal aging include the speed of information processing (Verhaeghen and Salthouse, 1997), memory (Engle, 2002; Rieckmann et al, 2018), attention, and executive control (Miyake et al, 2000). Some cognitive functions, such as vocabulary and general information, remain stable throughout normal aging, at least until the seventh decade of life (Salthouse, 2010). Dopamine plays an important role in complex cognitive functions such as working memory, cognitive flexibility, language and thought, motor planning, abstract representation, temporal analysis/sequencing, and generativity (Volkow et al, 1998; Previc, 1999; Mozley et al, 2001). Previous studies have shown that the presynaptic striatal dopamine function declines with normal aging (Kaasinen et al, 2015; Matsuda et al, 2018). Dopamine has been postulated as one of the many pathological hypotheses for cognitive impairment in PD (Bosboom et al, 2004; Hirano et al, 2012; Biundo et al, 2016)
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