Cognitive impairments are common in Parkinson's disease, with a significant impact on the morbidity and mortality rates of the disease, they can present as mild cognitive impairment even in the early stages of the disease. The International Movement Disorders Society has proposed diagnostic criteria for Parkinson's dementia and mild cognitive impairment (MCI) in Parkinson's disease, to provide correct diagnosis, and improve sensitivity and specificity of these diagnoses compared to the Diagnostic and Statistical Manual of Mental Disorders (DSM IV). There are certain risk factors for cognitive impairment in Parkinson's disease with cumulative risk. Their recognition is also important for early diagnosis of the disease.