Investigation of Memantine in the Treatment of Memory, Concentration or Attention Problems

Inclusion Criteria: * Subjective worsening of memory, concentration or attention problems for longer than 6 months * Subject can confirm that a relative or friend has noticed the memory, concentration or attention problems of the subject * Experience of the memory, concentration or attention problems at least four times per week Exclusion Criteria: * Significant neurological disease or major psychiatric disorder (e.g. diagnosis of psychosis or dementia) * Significant systemic illness, such as cancer, heart or kidney failure, uncontrolled diabetes * History of stroke or seizure, or myocardial infarction within the last year (e.g. by inclusion questionnaire, physician interview)