Long-term outcome of depressive pseudodementia in the elderly

BACKGROUND: The term depressive pseudodementia has proved to be a popular clinical concept. Little is known about the long-term outcome of this syndrome. AIMS: To compare depressed elderly patients with reversible cognitive impairment and cognitively intact depressed elderly patients. METHODS: All patients suffering from moderate or severe depression admitted to St Margaret's Hospital, UK as inpatients or day hospital outpatients between January 1 1997 and December 31 1999 (n=182) were screened for entry into the study. Eligible patients were divided into those presenting with pseudodementia and those who were cognitively intact and followed up for 5 to 7 years. RESULTS: Seventy-one point four percent of those suffering from pseudodementia had converted into dementia at follow-up compared to only 18.2% in the cognitively intact group. The relative risk was 3.929 (95% CI: 1.985 to 7.775) and the 'number needed to harm' 1.88. CONCLUSIONS: Reversible cognitive impairment in late-life moderate to severe depression appears to be a strong predictor of dementia. Inpatients and day hospital outpatients with depressive pseudodementia should probably have a full dementia screening, comprehensive cognitive testing and ongoing monitoring of their cognitive function.