Depression and dementia: the multi-faceted relationship

Depression and dementia: the multi-faceted relationship 1 The relationship between depression and dementia has been noted since antiquity and still eludes our precise understanding.Rosen (1961) notes that in the ninth century A.D. Rhazes, the Persian physician, mentions melancholy as an inevitable condition in the lives of old and decrepit persons.Later, both Robert Burton (Anatomy of Melancholy) and William Shakespeare, among others, commented on the association between cognitive and affective change.It is now established that cognitive change is part of the symptomatology of primary depressive illness and it is, of course, the cardinal feature of the syndrome of dementia.Depressive illness is found predominantly as a condition of the middle-aged and the elderly; 90% of the dementias are found in the senium, i.e. beyond the age of 65.Hence, an association at the very least between depression and dementia is«to be expected.As both depression and dementia are heterogeneous collections of conditions, the precise relationship will, not surprisingly, be a complex one.Furthermore, depressive illness is still classified among the 'functional' psychiatric disorders, i.e. among those conditions which do not have a tangible organic causation, a state of affairs accepted despite its unsatisfactory nature.Evidence is accumulating that a substantial and growing proportion of depressive illnesses have neurobiological correlates and, as techniques advance, the position of some forms, at least, of depressive illness among the' functional' disorders may become an untenable one.The converse applies to dementia.Very early the dementias became equated with 'organic' illness.But as knowledge has grown and our conceptualization of dementia has changed, we are now prepared to accept that the dementia syndrome may have 'organic' as well as 'functional' causation.A recent paper on dementia caused by depression (Rabins et al. 1984) emphasizes this point.Dementia is nowadays defined as an acquired, global condition, with intellectual deterioration, memory impairment and personality disorganization in the presence of unimpaired consciousness (e.g.Lishman, 1978).As depressive illness is acquired, global in its manifestation and occurs in the presence of unimpaired consciousness, it is not difficult to see that any cognitive change in depressive illness, if it progresses to substantial deficits in intellectual, memory or personality functioning, will satisfy the criteria for the syndrome of dementia. CONCEPT OF'PSEUDODEMENTIA'There is therefore a prima facie case for depressive illness leading to one form of dementia.It was in the context of studying groups of patients with apparent dementia, with observable depression and a course dissimilar to that of the majority of demented patients with progressive and terminal illnesses, that the concept of 'pseudodementia' originated.Post (1962) has referred to Gaupp's (1905) andLange's (1928) descriptions of mild senile mental changes first emerging during affective illness and then disappearing on recovery from depression.Madden et al. (1952) found that 'symptoms ordinarily considered to indicate dementia (disorientation, defects in recent memory, retention, calculation and judgement).. .maydisappear on alleviation of the psychotic picture by means of short-term intensive therapy'.They applied the term 'pseudodementia' to those cases, who constituted 10% of their 300 cases of non-dementing psychoses.The concept of'pseudodementia' was thus based on three elements: