Current Australian clinical practice guidelines on dementia do not advocate routine serological screening for syphilis or HIV, unless the history suggests the patient is at risk.11 Other investigations may be necessary if abnormal neurological signs are present.
The past decade has seen neuroimaging take on a broader role in patients with dementia syndromes, moving from an emphasis on ruling out reversible and treatable causes of dementia to inclusion of diagnostic subtyping of neurodegenerative diseases. Recent studies have found differing patterns of morphological, physiological and pathological change in the various dementia syndromes.12
Broadly, neuroimaging can be classified as structural, functional or molecular, with the latter two modalities available predominantly in tertiary and academic settings.11 Structural imaging encompasses CT and MRI. MRI is specifically preferred in the first-line assessment of younger patients aged under 65 years, who are more likely than older people to have atypical and reversible causes of dementia.13 MRI, with its superior anatomical resolution, can assess for volumetric loss including hippocampal atrophy, which is an early sign of Alzheimer’s disease. It can also detect white matter and other changes suggesting small vessel disease. However, MRI requires specialist referral. CT is therefore more easily available and remains a way to rule out underlying pathology causing secondary dementia, including stroke, subdural haematomas, hydrocephalus and space-occupying lesions.
The common causes of dementia and MCI and their relative frequencies are listed in Table 3. As dementia and MCI differ only in the level of impairment, their causes are the same.
Any patient presenting with focal neurological signs, including signs of a movement disorder, should be referred to a neurologist.
If there is concern about dementia then it is recommended that the patient be referred for specialist assessment. This may be to a geriatrician, psychogeriatrician or neurologist who specialises in memory disorders, or a memory clinic if available. The specialist may perform a brief cognitive assessment or refer the patient for a detailed neuropsychological assessment if the pattern of cognitive impairment seems atypical, for clarification of dementia subtypes or because of patient preference.
Psychiatric and medical conditions may skew the results of neuropsychological assessment and should be treated if possible before the referral is organised, as described below. A psychiatric or psychogeriatric referral should be considered for patients with atypical mental health presentations or significant psychiatric histories.
Typically, patients and their families are anxious about a possible diagnosis of dementia, so assessment should be completed promptly and the diagnosis communicated sensitively and with adequate consultation time allocated. MCI, with its diagnostic instability, should be communicated as an abnormal condition with an uncertain course. Providing written materials and arranging follow up are particularly important to ensure the patient and their family understand the diagnosis and to assess for the psychosocial impact of the diagnosis.
Management includes general neuroprotective advice, treatment optimisation for comorbid conditions, rationalisation of medications with known cognitive impairment profiles and consideration of pharmacological treatments such as acetylcholinesterase inhibitors or memantine. Recommended websites and resources are listed in Box 2.
Neuroprotective and other advice
All patients should receive general neuroprotective advice. This includes advice about management of vascular risk factors, including blood pressure, diabetes, hypercholesterolaemia and weight. Blood pressure control may reduce dementia risk independent of stroke prevention.14
Advice and support should be provided for smoking cessation. Exercise should be encouraged, both aerobic exercise and resistance training. Moderation of alcohol intake is to be emphasised. Intellectual stimulation (especially with new, unfamiliar and somewhat difficult activities) and social contact are to be encouraged.15 There is some evidence that the Mediterranean diet may reduce the risk of MCI converting to dementia.5