Alzheimer's Disease & Dementia Initial Assessment

Clinical Presentation

The cognitive impairment associated with dementia is sufficient to cause a decline in occupational and social functioning of the individual. The severity and global nature of cognitive impairment and the accompanying functional disability differentiate it from the relatively mild and variable cognitive decline associated with normal aging.

Alzheimers Disease & Dementia_Initial Assessment

History

With dementia, consciousness is usually not affected at an early stage. It is usually accompanied by or preceded by deterioration in emotional control, social behavior or motivation and sleep disturbances.

Clinical assessment should include, but should not be limited to, careful evaluation of medical, psychiatric, neurological, medication and social history, and detailed review of cognitive and behavioral symptoms from the patient and the caregiver.

Physical Examination

In approaching dementia, it is important to exclude treatable causes which may be contributory. A full neuropsychological and neuropsychiatric assessment is warranted. It is important to note that neuropsychological testing is more sensitive in exposing the presence of cognitive dysfunction, especially when screening tests (eg Montreal cognitive assessment [MoCA], mini-mental state exam [MMSE]) are normal.

Diagnosis or Diagnostic Criteria

Diagnostic Guidelines

The diagnosis of the subtype of dementia is done by using the international standard criteria (DSM-5). The basis of diagnosis is clinical assessment.

Alzheimer's Disease

The diagnosis of AD is made when the typical degenerative syndrome is present. Definitive diagnosis is only confirmed upon microscopic examination of the brain, usually at autopsy. On MRI, there is hippocampal atrophy (medial temporal atrophy) and/or global cortical atrophy thus supporting the diagnosis of AD in a patient with the typical clinical presentation. Other tests such as amyloid PET scan, cerebrospinal fluid (CSF) amyloid and tau levels may help in the diagnosis of AD.  

Vascular Dementia

It is diagnosed by history, presence of focal neurologic signs and symptoms, and/or findings in imaging studies with clear evidence of cerebrovascular events.  

DLB

In patients with DLB, there is the presence of Lewy inclusion bodies in the cerebral cortex upon histopathological examination. DLB may be diagnosed based on history, physical examination, and findings on ancillary procedures (eg MRI, brain fluorodeoxyglucose [FDG]-PET scan, dopamine transporter SPECT scan, metaiodobenzylguanidine [MIBG] myocardial scintigraphy). On MRI, there is absent or minimal medial temporal lobe atrophy, generalized cortical atrophy with normal hippocampal size.

Screening

Cognitive and Mental State Examination

The following screening tests can be used: MoCA, 7-minute screen, memory impairment screen (MIS), MMSE, abbreviated mental test, and clock drawing test.

With the interpretations of the scores, it is important to consider other factors that may affect the performance (eg educational level, social class, cultural background, literacy, language or other communication difficulties). Upon screening, referral to a memory clinic with multidisciplinary collaborative care is crucial for early and accurate diagnosis and management.