Effect of levodopa on cognitive function in Parkinson’s disease with and without dementia and dementia with Lewy bodies
- 1Institute of Ageing and Health, Wolfson Research Centre, Newcastle General Hospital, Newcastle upon Tyne, UK
- 2Cognitive Drug Research (CDR), Goring on Thames, UK
- Correspondence to: S A Molloy Department of Neurology, Newcastle General Hospital, Westgate Road, Newcastle upon Tyne NE4 6BE, UK;Sophie.molloy{at}btopenworld.com
- Received 18 May 2006
- Accepted 19 August 2006
- Published Online First 4 September 2006
Abstract
Background: Levodopa (L-dopa) is the gold standard treatment for Parkinson’s disease, but a lack of clear efficacy combined with a perceived liability to neuropsychiatric side effects has limited L-dopa use in patients with parkinsonism and dementia. Therefore, the effect of L-dopa on the cognitive profile of dementia with Lewy bodies (DLB) and Parkinson’s disease with dementia (PDD) is unclear.
Aim: To ascertain the acute and long-term effects of L-dopa on aspects of attention and cognition in patients with DLB and PDD, and to compare these with the effects in Parkinson’s disease.
Method: Baseline cognitive and motor function was assessed off L-dopa in patients with Parkinson’s disease (n = 22), PDD (n = 27) and DLB (n = 11) using standard “bedside” measures and a computerised programme detecting reaction times and accuracy. All patients then underwent an acute L-dopa challenge with subsequent subjective and objective analysis of alertness, verbal recall, reaction times and accuracy. The same parameters were measured after 3 months on L-dopa to assess the prolonged effect.
Results: Acute L-dopa challenge considerably improved motor function and subjective alertness in all patients without compromising either reaction times or accuracy, but increased fluctuations were noted in both groups with dementia. Neuropsychiatric scores improved in patients with Parkinson’s disease both with and without dementia on L-dopa at 3 months. Although patients with Parkinson’s disease also had better mean global cognitive function at this time, mean verbal attention and memory deteriorated, and patients with PDD had slower reaction times in some tests. No patient had a marked deterioration over this time. Patients with DLB did not experience any adverse cognitive or neuropsychiatric effects after 3 months of L-dopa treatment.
Conclusion: The use of L-dopa in patients with parkinsonism with dementia does not adversely affect cognitive function.
- ChEI, cholinesterase inhibitors
- COG RT, cognition reaction time
- CRT, choice reaction time
- CRT ACC, CRT response accuracy
- CRTSD, CRT standard deviation
- CVARCRT, coefficient of variation in choice reaction time
- DLB, dementia with Lewy bodies
- DPIC RT, delayed picture recognition reaction time
- DVIG RT, digit vigilance reaction time
- L-dopa, levodopa
- MMSE, Mini-Mental State Examination
- NPI, Neuropsychiatric Inventory
- NWM RT, numeric working memory reaction time
- PDD, Parkinson’s disease with dementia
- RDS, reverse digit span
- SRT, simple reaction time
- UPDRS, Unified Parkinson’s Disease Rating Scale
- VAS, Visual Analogue Scale
Footnotes
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Published Online First 4 September 2006
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Competing interests: None declared.
