Table 1. Criteria for the diagnosis of probable and possible Parkinson’s disease dementia ¹ .

The diagnosis is probable when:

A. Core features must be both present.

1. Diagnosis of Parkinson’s disease according to specific “diagnostic criteria” *

2. A syndrome of “cognitive decline” with insidious onset and slow progression, developing within the context of established PD and diagnosed by history, clinical, and mental examination, defined as:

- Impairment in more than one cognitive domain (including: attention, executive functions, visuo-spatial functions, memory and language)

- Decline from a premorbid level of functioning

- Deficits severe enough to impair daily life (social, occupational, or personal care), regardless of the impairment from motor or autonomic symptoms

B. Associated clinical features.

Typical profile of cognitive deficits including impairment in at least two of the four core cognitive domains (impaired attention which may fluctuate, impaired executive functions, impairment in visuo-spatial functions, and impaired free recall which usually improves with cueing)

Behavioral features such as apathy, changes in personality and mood, hallucinations, delusions, and excessive daytime sleepiness may be present (but are not necessary for diagnosis)

C. Features which do not exclude PDD, but make the diagnosis uncertain.

Existence of any other abnormality which may cause cognitive impairment but is not as the cause of dementia, e.g., presence of relevant vascular disease in imaging.

The time interval between the development of motor and cognitive symptoms is unknown**

D. There are none of the following features suggesting other conditions or diseases as the cause of mental impairment, which would hinder an accurate diagnosis of PDD: delirium, diagnosis of major depression, evidence for diagnosis of probable vascular dementia.

The diagnosis is possible when:

A. Core features must be both present.

B. The cognitive decline presents with atypical profile of cognitive impairment in one or more domains, such as prominent or receptive (fluent) aphasia or pure storage-failure type amnesia (memory does not improve with cueing or in recognition tasks) with preserved attention.

or

C. There are features that make the diagnosis uncertain (e.g., presence of relevant vascular disease in imaging).

or

D. Time interval between the development of motor and cognitive symptoms is unknown (“1-year rule”)

or

E. There are features suggesting other conditions or diseases as causes of mental impairment (delirium, diagnosis of major depression, evidence for diagnosis of probable vascular dementia)

* United Kingdom Parkinson’s Disease Society Brain Bank diagnostic criteria (20) for PD or another validated criterion; ** Refers to the “1-year rule” to differentiate PDD from Lewy body dementia. PDD develops within the context of established PD or arbitrarily at least a year after the onset of the classic motor symptoms.