Age-related decline in striatal volume in monkeys as measured by magnetic resonance imaging.

Age-related declines in striatal markers for the dopamine system have been demonstrated in several species. The current study investigated structural changes during aging in the rhesus monkey striatum. Male monkeys were studied using a volumetric spoiled gradient recall (SPGR) magnetic resonance imaging protocol. The caudate nucleus and putamen were segmented by manual tracing using landmarks made in the orthogonal planes. The whole brain volume (defined as volume of gray and white matter plus cerebrospinal fluid in ventricles and sulci) was measured using a semi-automated algorithm. There was no correlation between age and whole brain volume. There were age-related declines in normalized (i.e. brain region/whole brain volume) caudate nucleus and putamen volumes. Monkeys in the young group (n = 7, 39-45 months old) had larger volumes of both the caudate nucleus and putamen than animals in the middle-age (n = 5, 120-180 months) or old (n = 7, 291-360 months) groups. The current results provide normative data to assess potential interventions (e.g. caloric restriction) in the aging process.