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Based on efficacy and safety data, several drugs have been approved for symptomatic improvement of dementia of the Alzheimer type and one for the symptomatic improvement of dementia associated with Parkinson's disease. However, established treatment effects must be considered as modest. Randomized clinical trials in other subtypes of dementia (e.g. vascular dementia) have not been able to demonstrate clinically relevant symptomatic improvement, nor has it yet been possible to establish disease-modifying effects in any dementia syndrome or its subtypes. Recent progress in basic science and molecular biology of the dementias has now fostered new interest for more efficacious symptomatic treatments as well as for disease-modifying approaches in the degenerative dementias. For regulatory purposes this requires better standardization and refinement of diagnostic criteria, which allow the study of homogeneous disease populations in specialized academic centers as well as in the general community setting. Depending on the disease stages (early versus late, mild to moderate to severe impairment) and disease entities, distinct assessment tools for cognitive, functional and global endpoints should be used or newly developed. The typical design to show symptomatic improvement is a randomized, double-blind, placebo-controlled, parallel group study comparing change in two primary endpoints, one of them reflecting the cognitive domain and the second preferably reflecting the functional domain of impairment. The changes must be robust and clinically meaningful in favor of active treatment versus placebo. If a treatment claim for prevention of the emergence, slowing or stabilizing deterioration is strived for, it has to be shown that the treatment has an impact on the underlying neurobiology and pathophysiology of the process of dementia. Establishing such an effect in a highly variable progressing syndrome is complex and difficult; however, a variety of trial designs has been provided, including baseline designs, survival designs, randomized start or randomized withdrawal designs, with or without incorporation of biomarkers as surrogate endpoints (e.g. magnetic resonance tomography, emission tomography, cerebrospinal fluid markers). To be accepted as a surrogate endpoint such a biomarker ideally should respond to treatment, predict clinical response and be compellingly related to the pathophysiological process of the dementia. However, careful and sufficient validation of proposed biomarkers as a potential surrogate endpoint is a prerequisite for acceptance by regulatory bodies. This review outlines the regulatory requirements for approval of a new medicinal product for symptomatic improvement or disease-modifying effects in patients with dementia, with special emphasis on the importance of validation of the assessment tools and potential surrogate endpoints based on recent experience and discussion regarding anti-dementia drugs in the European framework.

Treatment of Alzheimer's disease (AD) that combats progressive functional deterioration can improve the patient's quality of life and reduce caregiver burden. Memantine, a moderate affinity N-methyl-D-aspartate receptor antagonist, reduces global deterioration in AD patients and provides cognitive and functional benefits relative to placebo. Two previous studies reported statistically significant benefits of memantine for overall functional ability on the Alzheimer Disease Cooperative Study Activities of Daily Living Inventory modified for severe dementia (ADCS-ADL(19)), Functional Assessment Staging, and G2 scale. The present study reports a single-item analysis of the ADL scales from the two trials and shows that patients treated with memantine demonstrated a numerical advantage over placebo on all items assessed. These results help to translate the positive effects of memantine into specific aspects of functional ability, information that is relevant to AD patients and their families as well as to researchers interested in the assessment of functional ability in AD clinical trials., (Copyright 2004 S. Karger AG, Basel)

Objective: To evaluate the efficacy and safety of galantamine in the treatment of Alzheimer's disease., Design: Randomised, double blind, parallel group, placebo controlled trial., Setting: 86 outpatient clinics in Europe and Canada., Participants: 653 patients with mild to moderate Alzheimer's disease., Intervention: Patients randomly assigned to galantamine had their daily dose escalated over three to four weeks to maintenance doses of 24 or 32 mg., Main Outcome Measures: Scores on the 11 item cognitive subscale of the Alzheimer's disease assessment scale, the clinician's interview based impression of change plus caregiver input, and the disability assessment for dementia scale. The effect of apolipoprotein E4 genotype on reponse to treatment was also assessed., Results: At six months, patients who received galantamine had a significantly better outcome on the 11 item cognitive subscale of the Alzheimer's disease assessment scale than patients in the placebo group (mean treatment effect 2.9 points for lower dose and 3.1 for higher dose, intention to treat analysis, P<0.001 for both doses). Galantamine was more effective than placebo on the clinician's interview based impression of change plus caregiver input (P<0.05 for both doses v placebo). At six months, patients in the higher dose galantamine group had significantly better scores on the disability assessment for dementia scale than patients in the placebo group (mean treatment effect 3.4 points, P<0.05). Apolipoprotein E genotype had no effect on the efficacy of galantamine. 80% (525) of patients completed the study., Conclusion: Galantamine is effective and well tolerated in Alzheimer's disease. As galantamine slowed the decline of functional ability as well as cognition, its effects are likely to be clinically relevant.