The cognitive deficits described by this patient suggest possible dementia. There are many causes of adult onset dementia including primary degenerations, of which Alzheimer’s disease is the most common in adults. This is estimated to account for 50–60% of cases.^[1] Dementia may also be secondary to other conditions, such as vascular disorders, neoplasms, infections, inflammatory disorders, metabolic causes and inherited metabolic and storage disorders. Since this patient claims to be feeling otherwise medically well, secondary causes of dementia would be less likely. Likely differentials that should therefore be considered in this patient include:

Less likely differentials include:

It should be noted, however, that mixed pathologies are common. Alzheimer’s disease may be present concurrently with vascular causes of dementia in the older patient.

In the assessment of a patient with symptoms of dementia, it is important to determine whether there are any reversible and treatable causes of cognitive deterioration, and to exclude any other causes of dementia.

Physical examination in a patient with symptoms of dementia should therefore include:

The essentially normal examination findings make other causes of dementia less likely. Neurological examination is usually normal until later in the disease process of AD so this is still the most likely diagnosis in an apparently otherwise well male of 66 years of age.

The MMSE is commonly used as a first-line assessment of mental status by primary contact practitioners, however it has limitations and one must consider other factors that may affect performance, including educational level, skills, prior level of functioning and attainment, language, sensory impairment, psychiatric illness and physical or neurological problems. For example, the MMSE may not detect subtle memory loss, especially in well-educated patients^[3,4] while people of low intelligence and the poorly educated may score poorly in the absence of cognitive impairment.^[5] This patient’s MMSE score of 27/30 would be considered normal. However, he should still be referred for more specialist evaluation of cognitive function due to the limitations of this test.

The slightly hesitancy in naming the objects used while testing stereognosis, and in identifying letters and numbers while testing graphesthesia, in a patient with otherwise intact sensation, is most likely due to mild agnosia associated with dementia.

The patient should undergo further assessment of cognitive deficit. This is best undertaken by a specialist and should include multiple tests and longitudinal assessment in order to determine the true significance of the subjective memory complaints.

Other investigations should be undertaken to help rule out other causes of dementia. The patient should be referred to his medical practitioner for:

A midstream urine test is normally only required if delirium is a possibility, which is unlikely in this patient. Other further investigations, such as chest x-ray, electrocardiogram (ECG) and tests for syphilis serology or HIV, are only undertaken when there are risk factors or as determined by clinical presentation.^[6]

As noted above, this patient should be referred for specialist evaluation of his cognitive function. While current clinical guidelines treat AD as a diagnosis of exclusion in patients with memory impairment and cognitive disturbance for which there is no other demonstrable cause, there has been a call to revise the diagnostic criteria in light of the growing research evidence into new diagnostic tests. Distinctive and reliable biomarkers of AD are now available through structural MRI, molecular neuroimaging with PET, and cerebrospinal fluid analysis.^[7] It is hoped that these tests will help to diagnose AD in early stages before the development of frank dementia.

Familial aggregation in AD is strong in both early and late onset forms. However, the genes that have been discovered only explain a small proportion of AD patients and are mostly associated with the early onset presentation of the disease.^[8] Research is ongoing into genes that are associated with an increased risk of developing the more common late onset variant of AD.

A diagnosis of dementia has implications for seeking valid consent. Valid consent to treat should still be sought and this should include informing the patient of treatment options and checking that they understand. There should be no coercion and clinicians should check that the patient continues to consent to treatment over time. If the patient lacks or reaches a point where they lack the capacity to make a decision, in the United Kingdom the provisions of the Mental Capacity Act 2005 must be followed.^[9] No-one can give consent on behalf of an incompetent adult, however clinicians may still decide to undertake assessment and care of such a patient if the assessment or care would be in the patient’s best interests.