Cognition in Parkinson's disease

Abstract

Cognitive decline is now recognised as a common non-motor symptom of Parkinson’s disease, and it has been the subject of increasing research in recent decades. Cognitive deficits in Parkinson’s disease can be distinguished as dopaminergically-mediated executive dysfunction seen in the milder stages, versus a global dementia syndrome that can occur with disease progression. The neural basis of these deficits has been explored from the perspective of multimodal imaging techniques to measure the structural, functional and metabolic correlates of cognitive decline in Parkinson’s disease. Increasingly, changes in neurotransmitter systems beyond dopamine, including the noradrenergic, serotonergic and cholinergic systems, are being recognised for their contribution to cognitive decline. The impact of certain genetic variations on cognitive function has also been established, including links between cognitive decline and polymorphisms affecting COMT, MAPT, APOE and GBA genotypes. Although therapeutic options for cognitive decline are still far less established than for motor systems, both pharmacological and non-pharmacological strategies are continuing to develop.