Delirium may be more prevalent in elderly outpatients than has long been assumed. However, it may be easily missed due to overlap with dementia. Our aim was to study delirium symptoms and underlying somatic disorders in psycho-geriatric outpatients.
We performed a case-control study among outpatients that were referred to a psychiatric institution between January 1st and July 1st 2010 for cognitive evaluation. We compared 44 cases with DSM-IV delirium (24 with and 20 without dementia) to 44 controls with dementia only. All participants were aged 70 years or older. We extracted from the medical files (1) referral characteristics including demographics, medical history, medication use, and referral reasons, (2) delirium symptoms, scored with the Delirium Rating Scale-Revised-98, and (3) underlying disorders categorized as: drugs/intoxication, infection, metabolic/endocrine disturbances, cardiovascular disorders, central nervous system disorders, and other health problems.
At referral, delirium patients had significantly higher numbers of chronic diseases and medications, and more often a history of delirium and a recent hospital admission than controls. Most study participants, including those with delirium, were referred for evaluation of (suspected) dementia. The symptoms that occurred more frequently in cases were: sleep disturbances, perceptual abnormalities, delusions, affect lability, agitation, attention deficits, acute onset, and fluctuations. Drug related (68%), infectious (61%), and metabolic-endocrine (50%) disturbances were often involved.