Factor analysis of the Montgomery Aasberg depression rating scale in an elderly stroke population

Background Depression is frequent in elderly stroke patients, and the pathophysiology may involve psychological as well as organic mechanisms. Aim To explore construct validity of the Montgomery Aasberg Depression Rating Scale using factor analysis and investigate whether symptom clusters of depression after stroke are associated with patient characteristics. Methods A sample of 163 stroke patients was assessed by the Montgomery Aasberg Depression Rating Scale. Pre-stroke assessment was accomplished by means of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), the Barthel ADL Index and patient's medical history. Post-stroke assessment was performed with the Mini Mental State Examination (MMSE), the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), the Star Cancellation Test, the Barthel ADL Index, the modified Rankin Scale (mRS) and the National Institute of Health Stroke Scale (NIHSS). Information was collected from the patients' records. A principal components factor analysis followed by oblique rotation was performed. Results Among the patients, 56.4% scored between 7 and 19 on the Montgomery Aasberg Depression Rating Scale, and 13% had a score above 19. The factor analysis resulted in three factors, called anhedonia (lassitude, inability to feel, suicidal thoughts, loss of appetite), sadness (observed sadness, reported sadness, pessimism) and agitation (inner tension, lack of concentration, disturbed sleep). Anhedonia correlated with cognitive impairment, whereas sadness correlated with sensorimotor and cranial nerve deficits. Agitation had low internal reliability and did not correlate with any systematic patients characteristics. Conclusion We found three distinct factors. The factor anhedonia is related to cognitive impairment, sadness to neurological impairment due to the stroke and agitation to somatic factors not directly related to the stroke. Copyright (C) 2009 John Wiley & Sons, Ltd.