Putamen FDOPA uptake and its relationship tot cognitive functioning in PD.

Impaired executive functioning is frequently found in PD patients. As a result, impairments in the executive components of other cognitive functions such as memory, visuo-spatial functions and fluency are also present. From a neuroanatomical point of view, different loops are mediating cognitive, emotional and motor functions. The putamen is part of the motor loop, while the caudate nucleus is part of the motor loop but also of the cognitive loop. In PD, multiple neurotransmitter systems are involved in cognitive functioning, including the dopaminergic system. Cognitive functioning in PD is related to striatal FDOPA uptake. This is particularly true for the caudate nucleus, but also for the putamen. We found a relationship between putaminal FDOPA uptake and measures for executive functioning, memory and fluency in a group of 28 non-demented advanced PD patients. This is a surprising finding since the putamen is part of the motor loop, but not the cognitive loop. One possible explanation is that the putamen is involved in motor actions after cognitive switching and is therefore related to neuropsychological test scores, as these require motor responses.