Background: Parkinson’s disease (PD) affects more than 1% of the population aged over 65 years and manifests with both motor symptoms – bradykinesia, rest tremor, rigidity, and non-motor symptoms. Cognitive impairment and dementia are recognized non-motor symptoms that can significantly affect the quality of life of both the patient and caregivers and are a risk factor for institutionalization in nursing homes and a risk factor for early mortality. Cognitive impairment is frequent in Parkinson’s disease (PD) that can develop even before the diagnosis of Parkinson’s disease based on its motor features. Conclusions: There are several clinical, molecular, and imaging factors that constitute risk factors for the development of Parkinson’s disease dementia, in which basal cholinergic and prefrontal dopaminergic systems are involved. Histological changes are Lewy-body, Alzheimer, but also vascular pathology. Clinically can be distinguished subjective cognitive decline, mild cognitive impairment and, subsequently, Parkinson’s disease dementia. There are no remedies with a proven effect to prevent the occurrence of cognitive decline in PD. The only approved drug for already developed D-PD is the cholinesterase inhibitor – donepezil. Non-pharmacological interventions are thought to be beneficial. A multidisciplinary approach to cognitive impairment is recommended, with specific pharmaceutical treatment of the cognitive disorder and comorbidities, and appropriate rehabilitation.