'Am I losing my marbles Doc?'

Having decided that the patient has cognitive impairment, what are the clinical conditions to consider?

Where mild memory difficulties are the primary presentation, then mild cognitive impairment (MCI) amnesic type, may be the problem. These patients do not show problems in other cognitive domains (such as attention, concentration, language, visuo-spatial skills, and executive functions).

Many MCI patients remain stable over time but a proportion (perhaps up to a third) do deteriorate and covert into dementia over a two to four year period. These cases may be individuals with very early (prodromal) manifestations of Alzheimer's disease.

Unfortunately, it is not yet possible to predict with any certainty which patients will get worse as we are not clear about the causes of MCI. If cognitive impairment extends beyond memory to other domains then a diagnosis of dementia is more likely.

In the "baby boomer' age group and older the main dementia conditions to consider are Alzheimer's disease, vascular cognitive impairment, a combination of Alzheimer's disease and vascular cognitive impairment, Lewy body dementia, dementia associated with Parkinson's disease and other sub-cortical degenerations, normal pressure hydrocephalus, and fronto-temporal dementia or similar variants (semantic dementia, progressive non-fluent aphasia, logopenic progressive aphasia, and behavioral dementia).

Reversible causes of dementia need to be excluded (such as vitamin deficiencies, hormonal disturbances, or normal pressure hydrocephalus).

Depressive illness and delirium can also masquerade as dementia.

Thorough investigation of cognitive impairment involves a screening physical and neurological exam as well as routine blood tests and neuro-imaging studies. A list of possibly relevant laboratory tests follows. However, the choice of tests will depend on the clinical circumstances.

Consider ordering FBC, ESR, CRP, E/LFT's, glucose, Ca, Mg, phosphate, thyroid function, cholesterol and lipid profile, vitamin's B12, B1, B6, and D, folic acid, homocysteine, APO-e genotype, HIV and syphilis serology, urine analysis, and ECG. An MRI brain scan is the most useful brain imaging study (a CT with contrast is an alternative for patients unsuitable for MRI).

In addition to the usual report ask the radiologist to comment on regional and general atrophy, presence of normal pressure hydrocephalus, hippocampal volume, ventricle size, and presence of deep white matter ischemia. Single photon emission tomography (SPECT) (and PET if available) provides information on cerebral perfusion activity patterns that can help differentiate between Alzheimer's disease, vascular cognitive impairment, Lewy body dementia, and fronto-temporal dementia.

An EEG is sometimes indicated when delirium or unusual dementia conditions or seizure disorders are being considered. In the future CSF studies of amyloid and tau protein fragments will also help with diagnosis.

Treatment of mild cognitive impairment is directed towards preventing further deterioration and maximizing cognitive function. Interventions that focus on reducing risk factors for dementia and enhancing protective factors against dementia are the most appropriate. Memory clinics that offer these types of cognitive enhancement programs are available on the Gold Coast.