AGE-RELATED DECLINE IN STRIATAL DOPAMINE TRANSPORTER BINDING WITH IODINE-123-BETA-CIT SPECT

  • 1 July 1995
    • journal article
    • research article
    • Vol. 36  (7) , 1175-1181
Abstract
The effect of age on human striatal dopamine (DA) transporters was investigated with SPECT using the ligand [I-123]2 beta-carbomethoxy-3 beta(4-iodophenyl)tropane ([I-123]beta-CIT). Methods: iodine-123-beta-CIT binding in the striatum was examined in 28 healthy human subjects (14 men, 14 women) who ranged in age from 18 to 83 yr. Following injection with [I-123]beta-CIT (mean +/- s.d. = 9.9 +/- 1.2 mCi), subjects were scanned with the brain-dedicated CERASPECT camera. A reconstructed transaxial slice 13.3-mm thick at the level of maximal striatal activity was used to determine tracer uptake in striatal and occipital regions of interest. The stability of regional uptake on Day 2 (approximately 18-24 hr postinjection) permitted estimation of the specific-to-nondisplaceable equilibrium partition coefficient: V-3 '', calculated as (striatal - occipital)occipital uptake at equilibrium. Results: Values of V-3 '' ranged from 3.6 to 11.4 for this sample (6.7 +/- 1.9). V-3 '' showed a significant inverse correlation with age (r = -0.73, n = 28, p < 0.0001). Linear regression analysis revealed that V-3 '' declined by 51% over the age range studied or approximately 8% per decade. Conclusion: These findings confirm postmortem reports of dopamine transporter loss with aging. In vivo methodologies may permit the age-related degeneration of dopamine nerve terminals to be studied in relation to the cognitive and motor deficits that occur in normal aging.

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