PT  - JOURNAL ARTICLE
AU  - Martijn Muller
AU  - Roger Albin
AU  - Robert Koeppe
AU  - Michael Kilbourn
AU  - Kirk Frey
AU  - Nicolaas Bohnen
TI  - Postural sensory efficacy and striatal dopaminergic innervation in normal older adults
DP  - 2010 May 01
TA  - Journal of Nuclear Medicine
PG  - 160--160
VI  - 51
IP  - supplement 2
4099  - http://jnm.snmjournals.org/content/51/supplement_2/160.short
4100  - http://jnm.snmjournals.org/content/51/supplement_2/160.full
SO  - J Nucl Med2010 May 01; 51
AB  - 160 Objectives To investigate the relationship between striatal binding of [11C]-dihydrotetrabenazine (DTBZ), a vesicular monoamine transporter type 2 ligand, and sensory efficacy of postural control in older adults. Methods Twenty-two healthy subjects (age ≥ 50; 9 F; 68.7 ± 10.1 yrs) underwent dynamic [11C]DTBZ PET brain imaging and posturography. An estimate of sensory efficacy was obtained by sway assessment on a posture platform (Neurocom) using the Sensory Organization Test (SOT) protocol. Postural sway was described by root-mean-square (RMS), velocity (V), frequency (FREQ), and the 95% confidence ellipse area (AREA-CE) of the Center of Pressure (COP). Sensory efficacy was calculated for each of the COP variables as ratios of SOT#2-SOT#1, SOT#4-SOT#1, SOT#5-SOT#1 for somatosensory (SOM), visual (VIS), and vestibular (VEST) efficacy respectively. PET data were analyzed using bolus-infusion equilibrium kinetic modeling with the global neocortex as reference region. Sensory efficacy scores and striatal DTBZ distribution volume (DTBZ-DV) were statistically correlated (Spearman). Results Age did not correlate with either DTBZ-DV or with sensory efficacy ratios (for all COP parameters). Higher FREQ sensory ratios were associated with decreased striatal DV for SOM (ρ=-0.471, p=0.027), VIS (ρ=-0.771, p<0.001) and VEST (ρ=-0.584, p=0.004). Conclusions Compared to normal quiet stance (SOT #1), sway frequency under challenged sensory conditions (SOT’s #2, #4, and #5) is more compromised with decreased striatal dopaminergic activity in normal aging. The striatum is one of the important brain regions in the control of balance. Strong correlation of sway frequency with DTBZ-DV for the visual efficacy score suggests that striatal dopaminergic functioning may be especially important for maintaining balance when relying mostly on visual information. People with impaired proprioceptive function or vestibular dysfunction may especially be affected by age-associated striatal dopaminergic denervation. Research Support Department of Veterans Affair