Symptoms of Alzheimer's Disease

When considering the clinical phenomenology of Alzheimer's Disease (AD), it is useful to distinguish between symptoms, syndromes and diseases. The patient presents with symptoms and it is the clinician's task to describe the syndrome in the first instance and then, with appropriate futher investigations, make a disease specific diagnosis. In the dementia field, symptoms, syndromes and diagnoses are sometimes used interchangeably and this adversely affect patient management, especially now that described below occur in different syndromes including the demetia syndrome, delirium and simple amnesia.

Amnesia

Amnesia or memory loss, is invariable and is often the most prominent symptom and one of the earliest. Amnesia is most pronounced for recent events, resulting in the available memories being predominantly distant or remote. It is not clear why remote memories are relatively resistant to deterioration, or possibly recent memories fail because of storage impairment. In the practice, a patient will often recall precise details of childhood or early adulthood and be unable to recall events of the last day.

The earliest signs of memory impairment overlap with normal phenomena and often are recognised only in retrospect. Forgetting the names of recently introduced people, missing the odd appointment and mislaying items are all common to the human experience. However, with incipient AD these phenomena become more pervasive dan more severe.

Language Disorders

Difficulties with speech are common in AD but predominate in the some other dementias, especially the fronto-temproral dementias where relatively early mutism can occur. In AD the symptoms is more often word finding difficulty. These can be assessed by asking the patient to name simple objects and is used in some screening istruments. for example the MMSE which requires the patient to name a pen and a watch. More detailed word finding ability can be tested by asking the patient to name items of clothing and then parts of clothing, for example collar, lapel, sleeve.

Dyspraxia

Difficulties with complex tasks are one of the major determinants of long term care of patients with AD. Difficulties with preparing food, dressing and other such activities of daily living should be assessed carefully both by direct observation and by informant interview. The earliest signs of dyspraxia include subtle changes in dress - the normally immaculately turned out patient appearing somewhat more dishevelled. As the disorder progresses the patient needs prompting and the help to dress.

Depression

Detecting and treating depression in alzheimer disease (AD) is difficult but by no means impossible. Symptoms of depression are common and probably frequent in the early stages but are less often detected in the later stages. Studies of mood in dementia reflect the difficulty of determining when symptoms of depression amount to a depression syndrome: some studies have found rate as low as 25% in patients with AD whilst others have reported rates as AD is not refactory to treatment. However a particular problem arises as many of the older antidepressants exhibit significant anticholinergic activity.

Psychotic Symptoms

Mistaken beliefs are common in AD and these frequently amount to frank delusions. Prevalence rates between 10% and 30% have been reported in different studies. Most frequently encountered in clinical practice are simple delusions of a persecutory nature, often of theft. Patients will believe they have had something stolen and often identify specific persons as the culprits. If the identified person is a relative or carer this can have serious consequences for the provision of good quality care.

Hallucinations are even more difficult to assess because of difficulties in interpreting the experiences of patients with dementia. Visual Hallucinations have a special importance because they constitute one part of the triad of symptoms associated with lewy body dementia.

Personailty and Behavioural Changes

In the earlier stages of the illness personality remains intact, although there may be accentuation of long-standing traits, the acquisiton of new characteristics or acute changes in behaviour. Behavioural disturbance per se is perhaps the most difficult symptoms for carers to cope with, and is often the reason for consulting clinicians at all stages of the illness. Abnormal behaviours do not have a direct relationship to severity and can be transient. The most usual behavioural trait, present from the very earliest stage, is a narrowing of interests and activities.