Making a Diagnosis of Dementia
Dementia is diagnosed when there are cognitive or behavioural symptoms that interfere with the ability to function at work or at usual activities, that represent a decline from previous levels of functioning and that are not explained by delirium or a major psychiatric disorder.
The impairment must involve a minimum of two of the following domains:
1. Impaired ability to acquire and remember new information. This may present as repeating questions or conversations,
misplacing personal belongings, forgetting events and appointments, and getting lost on a familiar route.
2. Impaired reasoning and handling of complex tasks and poor judgment. This may manifest in poor understanding of
safety risks, inability to manage finances, poor decision-making ability, and an inability to plan complex or sequential
3. Impaired visuospatial ability. The person may be unable to recognize faces or common objects and may be unable to
operate simple implements or may be unable to dress themselves correctly.
4. Impaired language functions, speaking, reading and writing. There may be difficulty finding the correct word while
speaking, hesitations, and speech, spelling and writing mistakes.
5. Changes in personality or behaviour. Mood can fluctuate; there can be agitation, loss of drive and loss of initiative,
apathy, social withdrawal and reduced interest in previous activities.
At our Memory Clinic the first step in making an accurate diagnosis is taking the history of the problem from both the person themselves and a close family member. Physical and neurological examinations are carried out including measurement of weight, blood pressure, pulse, ECG and urinalysis. A Dementia Blood screen includes, among others, tests to specifically identify possible reversible causes including hypothyroidism and Vitamin B12 and Folate deficiency.
Cognitive functioning is then assessed using a variety of screening tools, the most common of which is the Mini Mental State Examination (MMSE). It has limitations in that highly educated people can achieve high scores despite significant dementia, and conversely people for whom English is not the mother tongue, or people with lower levels of education may achieve artificially low scores. More detailed cognitive assessment tools in use include the Montreal Cognitive Assessment (MOCA) and the Addenbrooke’s Cognitive Examination (ACE). Neuro psychological testing is extremely helpful in clarifying diagnostic subtypes and in very early presentations of Alzheimers disease.
Structural imaging of the brain with CT or MRI scans helps exclude tumors and strokes, and also helps to subtype the dementia, identifying Vascular dementia and Front temporal subtypes.