Recently, a strong interest has emerged in recognizing Parkinson's disease dementia (PDD) at a very early stage. However, the specific profile of the earliest stages of PDD is still unclear and a matter of considerable controversy. The objective of this study was to find out early neuropsychological markers for progression of dementia in this population. Fifty-eight patients with PDD were divided into 2 subgroups on the basis of the Mini-Mental State Examination: very mild and mild. The comparison with 26 normal controls shows that very mild PDD had deficits on attention/executive functions, naming, visuospatial/constructional abilities and retrieval of the episodic memory. Patients with mild PDD showed additional deficits on coding of episodic memory. Moreover, we found that in this early stage of PDD, the progression of dementia is mainly related to deterioration of attention/executive functions as well as retrieval and coding of episodic memory.