Cognitive Problems Varied and Frequent in Late-stage Parkinson’s

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Multiple cognitive difficulties, especially problems with memory, are quite common among people in the later stages of Parkinson’s disease, a study in these patients reported.

Its researchers found evidence of difficulties that ranged verbal learning to comprehension, with memory most severely affected in 64% of the patients evaluated, and signs of mild dementia in most of those who did not fully classify as having cognitive impairment, its researchers wrote.

The study, “Profile of cognitive impairment in late-stage Parkinson’s disease,” was published in Brain and Behavior.

Trouble with cognition is a frequent non-motor symptom of Parkinson’s disease. However, most formal research into patients’ cognitive profiles have focused on early disease stages, with little research into how this symptom tends to manifest in the late stages of Parkinson’s.

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A team of scientists in Portugal conducted neuropsychological assessments of 84 people with late-stage Parkinson’s disease (LSPD) attending a clinic in Lisbon. Among the patients, just over half (57.1%) were women with a mean age of 75.4 and an average disease duration of nearly 17 years. Nearly all (97.3%) were being treated with levodopa.

Patients were assessed for the presence of dementia — memory and thinking problems that interfere significantly with day-to-day life — based on the Movement Disorder Society Parkinson’s disease dementia (MDS PDD) criteria.

“To the best of our knowledge, this is the first study that applies the MDS PDD criteria in a sample exclusively consisting of LSPD patients, examined in their homes with a complete neuropsychological assessment,” the researchers wrote.

Nearly two-thirds of the patients (64.3%) met these criteria for Parkinson’s-related dementia. Statistical analyses showed no difference in dementia risk based on sex, age, education, disease duration, age at Parkinson’s onset, or levodopa treatment profiles.

Among the 30 people who did not fulfill criteria for dementia, most (83.3%) showed impairment on at least two neuropsychological tests, fulfilling the criteria for mild cognitive impairment or MCI. Only 5 of the LOPD patients showed no signs of cognitive problems.

“Almost all nondemented patients meet clinical criteria for MCI with multiple-domain impairment,” the researchers wrote.

The researchers noted that the most common type of cognitive impairment was memory problems, reported in 34.5% of patients without dementia and in 86.8% of those with dementia. Executive function — the ability to plan out and accomplish a task — also was frequently impaired among patients with dementia.

“Memory was the most frequently impaired cognitive domain, with a strong contribution of attention deficit,” the researchers wrote. They noted that patterns of cognitive problems varied substantially from person to person.

Patients with more substantial Parkinson’s-related disability were more likely to experience dementia, statistical analyses showed.

The researchers noted a further need to study cognitive problems in people with late-stage Parkinson’s, particularly stressing the need for studies that evaluate how patients’ experiences change over time.