The natural history of mental disorder in old age: Alzheimer's disease and depressive illness compared.
BACKGROUND
Depressive illness (DI) and Alzheimer's disease (AD) are important causes of morbidity in old age and the relationships between these two disorders are uncertain.


METHODS
In a prospective, descriptive, comparative study of consecutive referrals aged over 65 years to one consultant, 218 patients with AD and 280 patients with DI were followed up for 15 years.


RESULTS
The prognosis of DI uncomplicated by physical illness at referral was reasonably good and 5-year survival was double that of AD. The rate of occurrence of AD in DI is no greater than in the general population. The higher mortality from cancer in DI than in AD is unexplained but may relate to differences in aetiology of these two disorders.


CONCLUSIONS
Although their symptoms frequently overlap, AD and DI are distinct disorders with very different prognoses and accurate diagnosis may have important implications for appropriate treatment.
Oxfordshire Mental Healthcare NHS Trust, Oxford, UK.
J R
JR
Robinson
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000401:mortality*; D003866:Depressive Disorder / Q000401:mortality*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D015996:Survival Rate; D006113:United Kingdom