Establishing the cause of memory loss in older people

Common causes of memory loss in older people are mild cognitive impairment, the various types of dementia, and psychiatric illness, mainly depression. Around 10% of patients with mild cognitive impairment progress to dementia each year. Alzheimer's disease accounts for 60-80% of cases. Other common types of dementia are vascular, fronto-temporal, Lewy body, Parkinson's, and mixed type dementia. There is evidence to suggest that dementia pathology is established before the onset of symptoms, and thus mild cognitive impairment can be considered as a predementia stage. NICE guidance suggests examination of: attention, concentration, short- and long-term memory, praxis, language and executive function. Particular attention should be paid to any signs of neglect, state of dress, agitation or poor attention. Dysphasia and difficulty in naming objects is often present. Mood symptoms (including suicidal ideation) may be primary or comorbid. Abnormal thoughts and perceptions should be probed for, as psychotic symptoms are common. Primary care options for cognitive testing include the General Practitioner Assessment of Cognition or the Abbreviated Mental Test Score. Physical examination should include observation of gait, inspection for tremor; examination for rigidity, bradykinesia, frontal release signs, upper motor neurone lesions, pulse and BP. Structural brain imaging can improve diagnostic accuracy, exclude other pathologies and act as a prognostic marker of dementia progression but the overlap in structural changes between the dementias makes imaging alone insufficient for diagnostic purposes. NICE guidelines recommend referral to a memory clinic for patients with mild cognitive impairment, those at high risk of dementia, such as patients with learning disabilities, Parkinson's disease, or patients who have had several strokes.