Dementia diagnosis

Be alert to changes in function or synptoms in aging patients, which might point to cognitive decline. Equally, don t let a dementia diagnosis distract you from addressing psychiatric comorbidities such as depression and anxiety. 

A diagnosis can be made only at autopsy therefore the diagnosis is established following an extensive history and physical examination, and by ruling out other potential causes of dementia. 

Knopman DS, DeKosky ST, Cummings JL, et al. Practice parameter diagnosis of dementia (an evidence-based review). Report of the quality standards subcommittee of the American Academy of Neurology. Neurology 2001 56 1143-1153. 

The most definitive diagnosis of AD is a postmortem examination of the brain for the presence of two characteristic lesions the neuritic plaque (NP) and the neurofibrillary tangle. Both structures were originally described in 1906 by Alois Alzheimer using silver-based histological stains. The discovery of NPs was hailed as a watershed moment in the history of neurological disease as it helped shift society s perception of age-related dementia from social stigma to physical disease [2]. 

McKeith, I. G., Galasko, D., Kosaka, K. etal. Consensus guidelines for the clinical and pathologic diagnosis of dementia with Lewy bodies (DLB) report of the consortium on DLB international workshop. Neurology 47 1113— 1124,1996. 

McKhann, G. M., Albert, M. S., Grossman, M. et al. Clinical and pathological diagnosis of frontotemporal dementia report of the Work Group on Frontotemporal Dementia and Pick s Disease. Arch. Neurol. 58 1803-1809, 2001. 

Depression and dementia have many symptoms in common, and the diagnosis of depression can be difficult, especially later in the course of AD. 

Konno S, Meyer JS, Terayama Y, Margishvili GM, Mortel KF. (1997). Classification, diagnosis, and treatment of vascular dementia. Drugs Aging. 11(5) 361-73. 

Nyenhuis DL, Goreiick PB. (1998). Vascuiar dementia a contemporary review of epidemiology, diagnosis, prevention, and treatment. J Am Geriatr Soc. 46(11) 1437-48. 

Cardiovascular and cerebrovascular disorders associated with lipid metabolism disturbance and atherosclerosis represent major risk factors for dementia (3,25,59). Atherosclerosis is the primary cause of heart disease and stroke in which genetic and environmental factors converge (553). More than 90% of patients older than 70-80 yr with dementia show signs of atherosclerosis in their arteries and a clear cerebrovascular component in their dementia process. It is very likely that pure AD is practically absent in octogenarians, in whom the prevalent diagnosis is vascular or mixed dementia (3,25,59), in which the APOE-4 allele also accumulates (18-20,554). 

The differential diagnosis of depression is organized along both symptomatic and causative lines. Symptomatically, major depression is differentiated from other disorders by its clinical presentation or its long-term history. This is, of course, the primary means of distinguishing psychiatric disorders in DSM-1V. The symptomatic differential of major depression includes other mood disorders such as dysthymic disorder and bipolar disorder, other disorders that frequently manifest depressed mood including schizoaffective disorder, schizophrenia, dementia, adjustment disorder, and post-traumatic stress disorder, and, finally, other nonpsychiatric conditions that resemble depression such as bereavement and medical illnesses like cancer or AIDS. 

Despite these clues, a definitive diagnosis often cannot be made. In that case, a prudent course is to treat what would be treatable. The initial evaluation should carefully look for treatable medical causes of dementia or depression. These include vitamin deficiency and hypothyroidism among others. If no medical causes are found, then treatment for depression should be started. If the patient is depressed and suffering from a pseudodementia, the patient can expect full recovery of memory as the depression resolves. But if the patient has a progressive dementia such as Alzheimer s disease, then treatment for depression has done no harm and may still provide some benefit. 

The course of illness depends on the cause of dementia. As a rule, the degenerative dementias are slowly progressive, taking several years to run their course from initial diagnosis to death. Vascular dementia, like other degenerative dementias, is slowly progressive but in a stepwise fashion. A patient with vascular dementia will function at a particular plateau until another small infarct causes a small but noticeable and sudden decline. 

Before diagnosing dementia, yon shonld consider any other condition that might impair intellectual function or that might masqnerade as an impairment of intellect. The differential diagnosis of dementia inclndes ... 

Hay DP, Klein DT (eds). Agitation in Patients with Dementia A Practical Guide to Diagnosis and Management. Clinical Practice Series. Washington DC American Psychiatric Pnblishing, 2003. 

M.D. Devous Sr., Functional brain imaging in the dementias Role in early detection, differential diagnosis, and longitudinal studies, Eur. J. Nucl. Med. 29 (2002) 1685-1696. 

I. G. McKelth, Dopamine transporter loss visualized with FP-CIT SPEC In the differential diagnosis of dementia with Lewy bodies. Arch. Neurol. 61 (2004) 919-925. 

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