Diagnosis of Alzheimer's disease
1. Does a dementia exist at all?
In a conversation, the doctor will initially check if there's an impairment of intellectual capacity, memory and speech, i.e. whether a dementia is present or not.
Own anamnesis - slight subjective symptoms (forgetfulness, word finding problems) need to be taken seriously, even if there are no measurable cognitive deficits or clear evidence of dementia.
Foreign anamnesis - essential when noticable impairments of memory and expression skills occur.
In addition to the concerned person, relatives have to be included in the conversation, because they know the concerned one best. They can also judge whether the patient's skills for everyday life, are impaired, such as planning and organizing of matters.
Suspected AD - creeping start, more clearly under stress, further slow progression
2. Alzheimer's disease or other dementia?
Is Alzheimer's disease the cause of the deterioration in mental abilities? To answer that question other diseases have to be excluded. Only then the doctor is able to diagnose Alzheimer's disease at a high rate of probability. In addition, other diseases that might be treatable can be filtered out.
Cognition: concentration, learning, remembering, word finding, comprehension, reading, writing
Behaviour: mood, interest, drive, appetite, sleep, aggression, lack of tact
Everyday tasks: work, hobbies, household, clothing, hygiene
For a separation from other similar diseases, further examinations are necessary.
Here, the doctor gets an overview of the physical condition of the patient. Moreover, he can gain information on other diseases that may be responsible for the problems, a noticeable tremor e.g. could be a sign of Parkinson's disease.
- outer appearance (tidy),
- Is he/she depressive?,
- continuation of social conventions,
- understanding of language and gestures,
- responding appropriately,
- Physical examination: testing of interaction skills
Cognitive tests - brain power
Cognitive ability tests provide valuable information that can be used to determine the extent of damage and the affected areas. It often makes sense to repeat a test after six months in order to recognize a stop or progress of degradation. Experienced doctors and psychologists have access to a whole series of tests and assessment procedures. Usually, only a short cognitive performance test is required.
MMSE (Mini-Mental State Examination):
- Visual-motoric abilities
Clock drawing test: unproblematic thinking, visual-constructive performance; sensitive in mild dementia.
- Very good for early detection of dementia
- 5 exercises for the functions of verbal memory, verbal fluency, intellectual flexibility and attention
- Duration - 8 to 10 minutes
- Test scores – for under and over 60 years - separated, regardless of educational level
- Over 13 points: adequate cognitive performance
- 9-12 points: mild cognitive impairment
- Less than 8 points: suspected dementia
TFDD(test for early detection of dementia with depression definition)
- Mixed methods consisting of knowledge questions and tasks relevant for everyday life
- Additional assessment of the mood
- Integrated clock drawing test
- Duration: 10 to 15 minutes
- High sensitivity for incipent cognitive impairments
- The daily living skills and the ability to support themselves depend closely on cognitive performance, but also on other factors (hearing, vision, motor functions)
- Therefore, the management of everyday life is assesed with the so-called functional or rating scales
- Covered are:
basal functions of independency (dressing, eating, walking)
complex activities of daily living (telephoning, shopping, deal with money)
FAST (Functional Assessment Staging)
- 7 stages of dementia
- Stage 1: no difficulties
- Stage 2: mislays objects, word finding difficulties
- Stage 7d: can not sit independently
- Stage 7f: Can not lift the head
- Allows an assessment of everyday competence and self-care in a short time
- Other aspects such as concentration, short-term and long-term memory, orientation, language, psychomotor performance, mood and behavior, constructive character and numeracy skills are covered by the Reisberg scale GDS and BCRS.
- Developed for nurses
- Can be filled out by relatives as well
- 30 questions – about 20 min.
- standardized questionnaires (daily activities, self care, memory performance, mood, social behavior)
- Changes of experience and behavior (delusions, hallucinations, depression, apathy, restlessness)
- they sometimes occur months before the diagnosis
NPI (Neuropsychiatric Inventory)
- Third-party assessment scales
- Delusions (danger, strangers in the house)
- Hallucinations (abnormal sensations)
- Agitation / aggression (uncooperative, kicks the furniture, throwing objects)
- Depression (sad, dejected, wishes to die, whining)
- Fear (weak, unable to relax themselves, increased tension)
- Elation / euphoria (abnormally happy, funny)
- Apathy / indifference (less interest, enthusiasm)
- Disinhibition (impulsive, rude)
- Irritability / lability (bad temper, quarrelsome)
- Anomalous motor behavior (motorically extremely restless)
- Sleep problems (waking up, walking around, sleeping excessively much)
- Eating disorders (anorexia, "strange" eating habits)
- Objective: Changes in the behavior of patients during a specified period
- Assessed are: frequency, severity, impact on the caregiver
- Duration: about 15 min.
- Progression observations of behavioral disorders
- The relative has to assess the type and severity of 25 symptoms for the period of the last 2 weeks
- 25 symptoms distributed in 7 areas: paranoid ideas and delusions, hallucinations, impaired motor skills, aggressiveness, day / night rhythm, affective disorders, anxiety and phobias
- Four-level rating
- Duration: about 20 min.
This includes a basic range of laboratory tests: ECG, EEG, imaging technique (MRI / CT)
- Purpose: Exclude secondary forms of dementia and detect other illnesses
- CBC, differential count, ESR, glucose, electrolytes, cholesterol, creatinine, thyroid parameters (TSH basal), vitamin B12 and folic acid
- Cerebrospinal fluid - "Dementia marker: beta-amyloid peptides (Aß-peptides), tau proteins
- In AD, the Aß42-peptide in the cerebrospinal fluid is reduced. This can be explained with the increased precipitation of Aß42 in the amyloid plaques
- Aß – Peptide: the main component of extracellular deposits, formed by cleavage of an amyloid precursor protein (APP). The diminished concentration is detected very early
- Tau protein is a component of the neuronal cytoskeleton. Hyperphosphorylization in AD (Alzheimer's disease); no stabilizing functions left --> destruction of the neuron --> tau protein is released; specific for AD: formation of neurofibrils, increase of p-tau 181
- The pathological neurofibrils formed in AD consist of hyperphosphorized tau filaments that are twisted into a double-helix
- In AD, the determination of the total tau group is suitable for the separation from mild, age-related cognitive deficits, especially in the early stages of the disease.
- Already in early stages of dementia: differentiation between normal aging and Alzheimer's
- A normal EEG doesn't exclude the diagnosis of dementia
- Noticeable slowdown of the EEG basic ativity
- CT and MRI are essential in diagnosis of dementia
- They create tomographies of the brain and allow insight into the structure of the brain
- Detection of causes and secondary dementias
Even in primary forms of dementia – characteristic morphological and functional patterns --> diagnostic clarification
Computed tomography (CT)
- Detection of structural changes in the brain, sub-or epidural hemorrhage, cerebral ischemia
- Presentation of typical athrophy patterns
Magnetic resonance imaging (MRI)
Smaller lesions in the brain parenchyma can also be detected. High sensitivity for subcortical structures and accurate representation of near-subcranial structures (hippocampus)
Nuclear medicine studies
- PET (positron emission tomography),
- SPECT (Single Photon Emission Computed Tomography)
- Mapping of regional brain perfusion and metabolism in the brain
- With PET - Presentation of Regional Glucose Utilization (at rest or during the implementation of a psychometric test)
- In AD: Glucose metabolism and blood flow to the brain - reduced temporoparietal