"Memantine-treated patients on stable donepezil therapy showed a significant difference over placebo in the percentage of patients who responded … at week 12 and maintained the response to week 24," according to principal investigator Michael Tocco, PhD, clinical investigator, medical affairs department, Forest Research Institute, Jersey City, New Jersey. The results suggest "that there can be a treatment response as early as week 12," he said.

The investigators were interested in the impact of using memantine while continuing donepezil because earlier research had shown that an interruption in pharmacological treatment for Alzheimer's disease could result in irreversible loss of cognitive and functional treatment benefits, Dr. Tocco said in a presentation on October 8^th.

Therefore, they conducted a post hoc analysis of a 24-week, double-blind, placebo-controlled trial of memantine in patients with moderate to severe Alzheimer's disease who had been stably maintained on donepezil. They wanted to see if adding memantine while continuing donepezil would help patients maintain their response on cognitive, functional, behavioral and global measures.

The original study used several tests to determine patients' baseline disease severity and response to treatment. These consisted of: the Severe Impairment Battery (SIB), the Alzheimers Disease Cooperative StudyActivities of Daily Living (ADCSADL19), the Neuropsychiatric Inventory (NPI), and the Clinicians Interview-Based Impression of Change Plus Caregiver Input (CIBIC-Plus).

Researchers analyzed the results to determine patients' cognition, functional abilities, behavioral outcomes, and global status. The study design defined maintenance of response as no change or improvement above baseline scores for both weeks 12 and 24.

When the patients on memantine and donepezil were compared with those on placebo and donepezil, the investigators documented a significantly greater percentage of memantine-treated patients who responded at week 12 and maintained their response at week 24. Those patients had significantly better scores on the SIB (P = .015), the ADCS-ADL19 (P = .037), the NPI (P = .009), and the CIBIC-Plus (P = .036).

The analysis showed that patients treated with memantine were more likely to have and maintain early treatment responses on the cognitive, functional, behavioral, and global measures.

These findings showed the importance of continuing memantine treatment when the agent is used in clinical practice, according to the investigators.

The study was supported by Forest Laboratories, Inc., which manufactures Namenda.


[Presentation title: Maintenance of Response to Memantine Treatment in Moderate-Severe AD Patients Receiving Stable Donepezil Treatment. Abstract S-21]

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