Elsevier

Neurobiology of Aging

Volume 57, September 2017, Pages 36-46
Neurobiology of Aging

Regular article
Reduced dopamine receptors and transporters but not synthesis capacity in normal aging adults: a meta-analysis

https://doi.org/10.1016/j.neurobiolaging.2017.05.006Get rights and content
Under a Creative Commons license
open access

Abstract

Many theories of cognitive aging are based on evidence that dopamine (DA) declines with age. Here, we performed a systematic meta-analysis of cross-sectional positron emission tomography and single-photon emission-computed tomography studies on the average effects of age on distinct DA targets (receptors, transporters, or relevant enzymes) in healthy adults (N = 95 studies including 2611 participants). Results revealed significant moderate to large, negative effects of age on DA transporters and receptors. Age had a significantly larger effect on D1- than D2-like receptors. In contrast, there was no significant effect of age on DA synthesis capacity. The average age reductions across the DA system were 3.7%–14.0% per decade. A meta-regression found only DA target as a significant moderator of the age effect. This study precisely quantifies prior claims of reduced DA functionality with age. It also identifies presynaptic mechanisms (spared synthesis capacity and reduced DA transporters) that may partially account for previously unexplained phenomena whereby older adults appear to use dopaminergic resources effectively. Recommendations for future studies including minimum required samples sizes are provided.

Keywords

Meta-analysis
Healthy aging
Dopamine
Receptors
Transporters
Synthesis capacity

Cited by (0)

1

Teresa Karrer is now at RWTH Aachen University, Germany.

2

Anika Josef is now at VDI/VDE-Innovation + Technik GmbH.

3

Gregory Samanez-Larkin is now at Duke University, USA.