Parkinson′s disease is a distinctive progressive disorder characterised clinically by tremor, rigidity, bradykinesia and postural imbalance. Although James Parkinson himself denied the presence of intellectual changes in the parkinsonian Disease, thorough exploration has revealed behavioural and cognitive changes to be explicit in the patients. India, along with its demographic shift and its overwhelming population growth, falls a victim to all old-age degenerative diseases. A large percentage of the elderly Indian population today suffers from Parkinsonian and related disorders. Disturbed cognition and neurobehavioral abnormalities are enough reasons for a falling ADL (activities of daily living) curve, and consequent distress to families of PD patients. Spontaneous involvement of one and all is required to not only intervene with the right pharmacological therapy, but also to empathize and develop the right attitude towards the affected person. Cognitive dysfunction in Parkinson′s disease is well established and its affection in the early stage has been reported. In this article. We attempt to review and update the various cognitive impairments that occur in all the Parkinson related disorders which necessitates diagnosis, management and rehabilitation to alleviate patients′ suffering. It also reviews the role of frontal lobe, dementia and depression with respect to these patients