In this study, memantine will be tested in a new indication: in the treatment of subjective memory, concentration, or attention problems (subjective cognitive impairment) in the absence of dementia.

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)