Alzheimer's%20disease%20-and-%20dementia Diagnosis

• In order for a diagnosis of dementia to be made, the cognitive impairment should be sufficient to cause a decline in the occupational and social functioning of the individual

Diagnostic Guidelines

• Diagnosis of subtype of dementia is done by using international standard criteria (DSM-5)
• Clinical assessment is the basis of diagnosis
  • Neuropsychological testing is used when dementia is not clinically obvious

Alzheimer’s Disease

• Diagnosis of Alzheimer’s disease should be made when typical degenerative syndrome is present
  • Definitive diagnosis is only confirmed on microscopic exam of the brain (usually at autopsy)
  • MRI findings of hippocampal atrophy (medial temporal atrophy) and/or global cortical atrophy may help in the diagnosis of Alzheimer’s disease in a patient with typical clinical presentation
  • Amyloid positron emission tomography (PET) scan and cerebrospinal fluid amyloid and tau levels may help in the diagnosis of Alzheimer's disease

Vascular Dementia

• Diagnosed by history, focal neurological signs and symptoms and/or imaging studies with clear evidence of cerebrovascular events

Dementia with Lewy Bodies

• Histopathologically, Lewy inclusion bodies are present in the cerebral cortex
• May be diagnosed on history, physical and  neurological examination, and ancillary procedures, such as structural MRI, brain fluorodeoxyglucose (FDG)-PET scan, Dopamine Transporter single-photon emission computed tomography (SPECT) scan and metaiodobenzylguanidine (MIBG) myocardial scintigraphy
  • MRI will show absent or minimal medial temporal lobe atrophy, generalized cortical atrophy with relatively normal hippocampal size

Clinical Assessment

Should include, but is not limited to, the following:

• Careful evaluation of medical, psychiatric, neurological, medication and social history
• Detailed review of cognitive and behavioral symptoms from patient and caregiver

• Exclude treatable causes which may be contributing to dementia
• Neuropsychological and neuropsychiatric assessment

Diagnostic Tests

• Complete blood count (CBC), serum electrolytes, liver function test, renal function tests, glucose, thyroid function, vitamin B12 and folate levels, and syphilis serology (if syphilis is suspected)
• Electroencephalography (EEG) may be useful if suspicious of CJD, underlying seizure disorder or in delirium
• Neuroimaging [magnetic resonance imaging (MRI), computed tomography (CT) scan]
  • Helps to determine dementia subtypes and rule out intra-cerebral pathology
  • Brain MRI is the preferred modality to assist with early diagnosis and detect subcortical vascular changes
  • Brain CT or MRI should be performed in hypertensive patients with cognitive decline to detect silent infarct, microbleed, or white matter lesion
• Neuropsychological testing
• Determination of cerebrospinal fluid (CSF) biomarkers and plasma markers are not recommended in the diagnosis of mild cognitive impairment
• Genetic testing and use of genetic marker APOE with or without plasma lipid is not routinely recommended

Cognitive and Mental State Examination

• Montreal Cognitive Assessment, 7-Minute Screen, Memory Impairment Screen, Mini-Mental State Exam, Abbreviated Mental Test or Clock Drawing Test
• Score interpretations should also consider other factors that may affect the performance (eg educational level, social class, cultural background, literacy, language or other communication difficulties)
• Refer to memory clinic with multidisciplinary collaborative care for early and accurate diagnosis and management of dementia