Delusional disorder in old age and the risk of developing dementia: a nationwide register-based study.
OBJECTIVE
To examine whether very late first-contact delusional disorder carries a risk for later development of dementia.


METHODS
By linkage of the psychiatric and the somatic nationwide registers of all out- and in-patients with hospital contact in Denmark, we included all 60+ patients with first ever from 1 January 1994 to 31 December 2001 with the index main diagnosis: delusional disorder. First contact osteoarthritis patients as well as the general population were used as controls. A total of 1,437 patients with persistent delusional disorder and 7,302 patients with osteoarthritis were included. Median follow-up time until first diagnosis of dementia at discharge was 1.87 and 4.40 years, respectively. The probability of getting a dementia diagnosis was estimated using Poisson regression models with dementia as the outcome of interest.


RESULTS
Patients with very late first-contact delusional disorder had an 8.14 (95% CI, 6.51; 10.19) times increased rate of subsequently developing dementia compared with very late first contact osteoarthritis patients. Compared with the general population the rate ratio was 5.49 (95% CI, 4.81; 6.26).


CONCLUSIONS
Very late first-contact delusional disorder increases the risk of subsequently getting a diagnosis of dementia 5-8 times compared with osteoarthritis patients and the general population.
Psychogeriatric Unit, Psychiatric Hospital, Hilleroed, Denmark. alko@noh.regionh.dk
Alex
A
Kørner
Ana G
AG
Lopez
Lise
L
Lauritzen
Per K
PK
Andersen
Lars V
LV
Kessing
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology*; D003718:Denmark; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis; D016012:Poisson Distribution; D012042:Registries; D012306:Risk; D018570:Risk Assessment; D012563:Schizophrenia, Paranoid