The Frontal Assessment Battery (FAB) is a cognitive test that incorporates several clinical assessments to screen for frontotemporal dementia (FTD), including S-word generation, similarities, Luria's test, grasp reflex, and the Go-No-Go test. Patients with FTD typically score lower on the FAB compared with healthy controls and even patients with mild Alzheimer's Disease (AD).
Although the FAB was designed for screening for frontotemporal dementia, it has also been used in other clinical settings, including frontal lobe dysfunction in schizophrenia,[1] executive dysfunction screen in Parkinson’s,[2] and executive cognitive dysfunction in substance dependence.[3] It can provide an objective measure to distinguish FTD from AD in patients with mild dementia.[4]
Ask the patient “In what way are they alike?”:
Abstract reasoning is impaired in frontal lobe disorders. Patients with frontal lobe dysfunction may be unable to establish an abstract link between similar items (i.e. - flowers). Instead, they may adhere only to the concrete aspects of objects (i.e. - saying “both are red,” or “one is round but the other is elongated”).
Tell the patient: “Say as many words as you can beginning with the letter 'S,' any words except surnames or proper nouns.”
Patients with frontal lobe lesions have difficulties navigating non-routine situations. Frontal lesions, regardless of side, tend to decrease verbal fluency. Left frontal lesions usually result in lower word production than right frontal lesions. Although the lexical fluency test has relatively poor localizing value, significant impairment is lateralizing to the left frontal lobe.[5]
Tell the patient: “Look carefully at what I’m doing.”
Prompt the patient: “Now, with your right hand do the same series, first with me, then alone.”
Now tell the patient: “Now, do it on your own.”
Patients with frontal lobe lesions are impaired in tasks that require temporal organization, maintenance, and execution of successive actions. Patients with some impairment will be unable to execute the “fist–palm–edge” series in the correct order. Patients who are severely impaired will be unable to learn the series at all. Patients may simplify the task (use two gestures instead of three) or show perseveration (repeating the same gesture).
Tell the patient: “Tap twice when I tap once.”
Tell the patient: “Tap once when I tap twice.”
The examiner now performs the actual following series: 1-1-2-1-2-2-2-1-1-2
This is a task assesses a patient's sensitivity to interference. When the verbal commands (Being told to “tap twice when I tap once”) conflict with sensory information (seeing the examiner tap twice and not once), deficits in behavioural self-regulation can be seen in patients with frontal lobe dysfunction. This task is similar to the Stroop Test. Patients with a frontal lobe lesion will usually fail to obey the verbal command and instead execute the echopractic movements by imitating the examiner.
Tell the patient: “Tap once when I tap once.”
Tell the patient: “Do not tap when I tap twice.”
The examiner now performs the actual following series: 1-1-2-1-2-2-2-1-1-2
This task measures the patient's inhibitory control. Withholding a response can be difficult for patients with damage to the ventral part of the frontal lobes. This difficulty in controlling impulsiveness can be assessed with the Go–No Go task, because the subjects must now inhibit the response (”Tap once when I tap twice.“) that they were previously given (in the Conflicting Instructions task), for the same stimulus (seeing the examiner tap twice). The patient must now inhibit a response that was previously given to the same stimulus (i.e. - not tapping at all when the examiner taps twice).
Tell the patient: “Do not take my hands.”
This task assesses for environmental autonomy. Patients with frontal lobe lesions can be overly dependent on environmental cues. Sensory stimuli can activate patterns of responses in these patients. These sensory stimuli and pattern of responses include: (1) seeing movement as an order to imitate (imitation behaviour), (2) seeing an object implies the order to use it (utilization behaviour), or (3) the sight or sensory perception of an examiner’s hands may compel the patient to take them (prehension behaviour). These abnormal behaviours (the spontaneous tendency to adhere to the environment) shows the lack of inhibition that is normally exerted by the prefrontal cortex. This is called the grasp reflex, and is a type of primitive reflex.
The sum of the sub-scores from each of the six components are added up to generate total score out of 18.
Using a cutoff score of 12/18 can reasonably differentiate FTD from mild Alzheimer's (sensitivity of 77% and specificity of 87%).[6] Age and education norms from an Italian population sample for normal scores are also available in the table below.[7] There is considerable variability based on education, with lower mean scores accepted as “normal” for those with less years of education.
20-29 | 30-39 | 40-49 | 50-59 | 60-69 | 70-79 | 80-89 | 90-95 | Total | |
---|---|---|---|---|---|---|---|---|---|
1-3 years education | - | - | - | 18 | 14.5 | 14.0 | 13.5 | - | 14.6 |
4-5 years education | - | - | 16.4 | 15.6 | 14.8 | 14.7 | 13.2 | 11.8 | 14.7 |
6-8 years education | 15.9 | 16.2 | 16.7 | 16.6 | 16.2 | 15.4 | 12.0 | 14.7 | 15.8 |
9-13 years education | 16.9 | 17.1 | 17.7 | 16.9 | 16.3 | 16.2 | 17.0 | 12.0 | 16.6 |
> 13 years education | 17.9 | 17.6 | 17.7 | 17.5 | 17.1 | 15.9 | 16.0 | 15.0 | 17.2 |
Total | 16.8 | 16.8 | 17.1 | 16.8 | 16 | 15.5 | 13.8 | 13.1 | 16.1 |