Frontal lobe disorder
Encyclopedia
Frontal lobe disorder is an impairment of the frontal lobe that occurs as a result of a number of diseases as well as head trauma. The frontal lobe
of the brain
plays a key role in higher mental functions such as motivation, planning, social behaviour, and speech production. A frontal lobe syndrome can result from a range of causes including head trauma, tumours, degenerative diseases,neurosurgery and cerebrovascular disease. Impairment of frontal lobe functioning is also found in a range of psychiatric conditions including schizophrenia
, attention deficit disorder and antisocial personality disorder
. Frontal lobe impairment can be detected by recognition of typical clinical signs, use of simple screening tests, and specialist neuropsychiatric testing.
The frontal lobe has three main areas, known as the precentral cortex, prefrontal cortex and the orbitofrontal cortex. These three areas are represented in both the left and the right cerebral hemispheres.
The precentral cortex or primary motor cortex
is concerned with the planning, initiation and control of physical movement. The dorsolateral part of the frontal lobe is concerned with planning, strategy formation, and other executive functions
. The prefrontal cortex in the left hemisphere is involved with verbal memory
while the prefrontal cortex in the right hemisphere is involved in spatial memory. The left frontal operculum region of the prefrontal cortex, or Broca's area
, is responsible for expressive language, i.e. language production. The orbitofrontal cortex is concerned with response inhibition, impulse control, and social behaviour.
, for example with loss of social awareness, disinhibition, emotional instability, aggression, irritability or impulsiveness (for example sexually inappropriate behaviour or spending money impulsively). Alternatively the disorder may become apparent because of mood changes such as depression
, anxiety
or apathy.
. Typically the person is lacking in insight and judgment, but does not have marked cognitive abnormalities or memory impairment (as measured for example by the mini-mental state examination
). With more severe impairment there may be echolalia
or mutism. Neurological examination
may show primitive reflexes
(also known as frontal release signs) such as the grasp reflex or the rooting reflex. These are reflexes normally found in babies, but normally suppressed and absent in adults. Akinesia (lack of spontaneous movement) and urinary incontinence
will be present in more severe and advanced cases. The frontal assessment battery (FAB), which includes simple tests of sequencing, behavioural inhibition, planning and frontal release signs, can be used as a screening test to elicit typical neurological and cognitive features.
test, planning can be assessed with the Mazes subtest of the WISC
, switching between plans is assessed with the Trail-making test
, and screening out distracting stimuli is assessed with the Stroop test.
Individuals with frontotemporal dementia
and Pick's disease
will show frontal cortical atrophy
on CT scans or MRIs. Frontal impairment due to head injuries, tumours or cerebrovascular disease will also be apparent on brain imaging.
The counterargument is that there is a central executive corresponding to areas within the frontal lobes which is responsible for much of the executive system and executive function in general, and that damage to this area causes dysexecutive syndrome.
Phineas Gage
, who suffered a severe frontal lobe injury in 1848, has been called a case of dysexecutive syndrome. But Gage's psychological changes are typically grossly exaggerated: of the symptoms listed above, the only ones Gage can even arguably be said to have exhibited (based on primary sources) are "anger and frustration," slight memory impairment, and "difficulty in planning".
In particular, the primary sources do not report utilisation behaviour, depression, aggression
, inappropriate sexual behaviour, or "inappropriate humour and telling of pointless and boring stories" (in fact, his audience was said to have found his stories entertaining). The oft-quoted statement by friends—that after the accident he was "no longer Gage"—admits interpretation as any number of behavioural or personality changes, not even necessarily of organic etiology. Although he was not able to return to his work for the railroad, after his physical recovery he was socially functional and self-supporting for the remainder of his life.
accidents, can cause damage to the orbitofrontal cortex. Pre-frontal lobotomies severing connections between the pre-frontal cortex and the rest of the brain, were effectively a form of iatrogenic trauma resulting in a frontal lobe syndrome.
may cause a stroke
in the frontal lobe.
, frontotemporal dementia
and Pick's disease
.
, depression, attention-deficit hyperactivity disorder
(ADHD), and antisocial personality disorder
or psychopathy
.
A large number of studies have documented abnormalities in working memory in schizophrenia, associated with disrupted functioning of the dorso-lateral prefrontal cortex. There is also evidence for disruption of neuronal connections between the temporal
and frontal lobes in people with schizophrenia. The characteristic dorso-lateral prefrontal cortex morphological abnormalities are said to be related to a general impaired ability to control and regulate behaviour, which would correspond to deficits in several functional areas in schizophrenia. A study of people with schizophrenia using MRI scanning and psychological assessment has also found that longer duration of illness was associated with lower gray matter
volume in the left dorsomedial prefrontal cortex and the right middle frontal cortex, and these changes were associated with impaired working memory, attention and psychomotor speed. Another MRI study of schizophrenia has found an association between orbitofrontal cortex volume reduction and a longer duration of illness, impaired executive functioning, and greater formal thought disorder.
Research on children with ADHD has shown a general reduction of brain volume, but with a proportionally greater reduction in the volume of the left-sided prefrontal cortex. These findings are in keeping with the core ADHD features of inattention, hyperactivity, and impulsivity, but other brain regions have also been implicated in the causation of ADHD. The prefrontal cortex is also implicated by functional magnetic resonance imaging (fMRI) studies which examine brain activation during tasks such as motor response inhibition; reduced prefrontal cortex activation is associated with higher ADHD behavioural scores.
Frontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
of the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
plays a key role in higher mental functions such as motivation, planning, social behaviour, and speech production. A frontal lobe syndrome can result from a range of causes including head trauma, tumours, degenerative diseases,neurosurgery and cerebrovascular disease. Impairment of frontal lobe functioning is also found in a range of psychiatric conditions including schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
, attention deficit disorder and antisocial personality disorder
Antisocial personality disorder
Antisocial personality disorder is described by the American Psychiatric Association's Diagnostic and Statistical Manual, fourth edition , as an Axis II personality disorder characterized by "...a pervasive pattern of disregard for, and violation of, the rights of others that begins in childhood...
. Frontal lobe impairment can be detected by recognition of typical clinical signs, use of simple screening tests, and specialist neuropsychiatric testing.
Anatomy and functions
ile:Prefrontal cortex.png|right|220px|The frontal lobe has three main areas, known as the precentral cortex, prefrontal cortex and the orbitofrontal cortex. These three areas are represented in both the left and the right cerebral hemispheres.
The precentral cortex or primary motor cortex
Primary motor cortex
The primary motor cortex is a brain region that in humans is located in the posterior portion of the frontal lobe. Itworks in association with pre-motor areas to plan and execute movements. M1 contains large neurons known as Betz cells, which send long axons down the spinal cord to synapse onto...
is concerned with the planning, initiation and control of physical movement. The dorsolateral part of the frontal lobe is concerned with planning, strategy formation, and other executive functions
Executive functions
The executive system is a theorized cognitive system in psychology that controls and manages other cognitive processes. It is responsible for processes that are sometimes referred to as the executive function, executive functions, supervisory attentional system, or cognitive control...
. The prefrontal cortex in the left hemisphere is involved with verbal memory
Verbal memory
Verbal memory is a term used in Cognitive Psychology that refers to memory of words and other abstractions involving language.-Verbal Encoding:Verbal Encoding refers to the interpretation of verbal stimuli...
while the prefrontal cortex in the right hemisphere is involved in spatial memory. The left frontal operculum region of the prefrontal cortex, or Broca's area
Broca's area
Broca's area is a region of the hominid brain with functions linked to speech production.The production of language has been linked to the Broca’s area since Pierre Paul Broca reported impairments in two patients. They had lost the ability to speak after injury to the posterior inferior frontal...
, is responsible for expressive language, i.e. language production. The orbitofrontal cortex is concerned with response inhibition, impulse control, and social behaviour.
History
Frontal lobe disorders may be recognized through a sudden and dramatic change in a person's personalityPersonality psychology
Personality psychology is a branch of psychology that studies personality and individual differences. Its areas of focus include:* Constructing a coherent picture of the individual and his or her major psychological processes...
, for example with loss of social awareness, disinhibition, emotional instability, aggression, irritability or impulsiveness (for example sexually inappropriate behaviour or spending money impulsively). Alternatively the disorder may become apparent because of mood changes such as depression
Depression (mood)
Depression is a state of low mood and aversion to activity that can affect a person's thoughts, behaviour, feelings and physical well-being. Depressed people may feel sad, anxious, empty, hopeless, helpless, worthless, guilty, irritable, or restless...
, anxiety
Anxiety
Anxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...
or apathy.
Examination
On mental state examination a person with frontal lobe damage may show reduced speech, with reduced verbal fluency and impaired expressive language. The person might have flattened or blunted affectAffect (psychology)
Affect refers to the experience of feeling or emotion. Affect is a key part of the process of an organism's interaction with stimuli. The word also refers sometimes to affect display, which is "a facial, vocal, or gestural behavior that serves as an indicator of affect" .The affective domain...
. Typically the person is lacking in insight and judgment, but does not have marked cognitive abnormalities or memory impairment (as measured for example by the mini-mental state examination
Mini-mental state examination
The mini–mental state examination or Folstein test is a brief 30-point questionnaire test that is used to screen for cognitive impairment. It is commonly used in medicine to screen for dementia...
). With more severe impairment there may be echolalia
Echolalia
Echolalia is the automatic repetition of vocalizations made by another person. It is closely related to echopraxia, the automatic repetition of movements made by another person....
or mutism. Neurological examination
Neurological examination
A neurological examination is the assessment of sensory neuron and motor responses, especially reflexes, to determine whether the nervous system is impaired...
may show primitive reflexes
Primitive reflexes
Primitive reflexes are reflex actions originating in the central nervous system that are exhibited by normal infants but not neurologically intact adults, in response to particular stimuli. These reflexes disappear or are inhibited by the frontal lobes as a child moves through normal child...
(also known as frontal release signs) such as the grasp reflex or the rooting reflex. These are reflexes normally found in babies, but normally suppressed and absent in adults. Akinesia (lack of spontaneous movement) and urinary incontinence
Urinary incontinence
Urinary incontinence is any involuntary leakage of urine. It is a common and distressing problem, which may have a profound impact on quality of life. Urinary incontinence almost always results from an underlying treatable medical condition but is under-reported to medical practitioners...
will be present in more severe and advanced cases. The frontal assessment battery (FAB), which includes simple tests of sequencing, behavioural inhibition, planning and frontal release signs, can be used as a screening test to elicit typical neurological and cognitive features.
Further investigation
A range of neuropsychological tests are available for clarifying the nature and extent of frontal lobe dysfunction. For example, concept formation and ability to shift mental sets can be measured with the Wisconsin card sortWisconsin card sort
The Wisconsin Card Sorting Test is a neuropsychological test of "set-shifting", i.e. the ability to display flexibility in the face of changing schedules of reinforcement. The WCST was written by David A. Grant and Esta A. Berg. The Professional Manual for the WCST was written by Robert K. Heaton,...
test, planning can be assessed with the Mazes subtest of the WISC
Wechsler Intelligence Scale for Children
The Wechsler Intelligence Scale for Children , developed by Dr. David Wechsler, is an individually administered intelligence test for children between the ages of 6 and 16 inclusive that can be completed without reading or writing...
, switching between plans is assessed with the Trail-making test
Trail-making test
The Trail-making test is a neuropsychological test of visual attention and task switching. The task requires a subject to 'connect-the-dots' of 25 consecutive targets on a sheet of paper or computer screen. Two versions are available: A, in which the targets are all numbers , and B, in which the...
, and screening out distracting stimuli is assessed with the Stroop test.
Individuals with frontotemporal dementia
Frontotemporal dementia
Frontotemporal dementia is a clinical syndrome caused by degeneration of the frontal lobe of the brain and may extend back to the temporal lobe...
and Pick's disease
Pick's disease
Pick's disease, is a rare neurodegenerative disease that causes progressive destruction of nerve cells in the brain. Symptoms include loss of speech , and dementia. While some of the symptoms can initially be alleviated, the disease progresses and patients often die within two to ten years...
will show frontal cortical atrophy
Atrophy
Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...
on CT scans or MRIs. Frontal impairment due to head injuries, tumours or cerebrovascular disease will also be apparent on brain imaging.
Dysexecutive syndrome
Dysexecutive syndrome consists of a number of symptoms which tend to occur together (hence it being described as a syndrome). Broadly speaking, these symptoms fall into three main categories; cognitive, emotional and behavioural. Although many of these symptoms regularly co-occur, it is common to encounter patients who have several, but not all of these symptoms. This is one reason why some researchers are beginning to argue that dysexecutive syndrome is not the best term to describe these various symptoms (see criticisms below). The fact that many of the dysexecutive syndrome symptoms can occur alone has led some researchers to suggest that the symptoms should not be labelled as a "syndrome" as such. Some of the latest imaging research on frontal cortex areas suggests that executive functions may be more discrete than was previously thought. The argument is that rather than damage to the frontal cortex areas causing dysexecutive functions in general, that damage to multiple frontal cortex areas that are close together (but responsible for different cognitive functions) can cause the various symptoms of dysexecutive syndrome.The counterargument is that there is a central executive corresponding to areas within the frontal lobes which is responsible for much of the executive system and executive function in general, and that damage to this area causes dysexecutive syndrome.
Cognitive symptoms
- Short attention spanAttention spanAttention span is the amount of time that a person can concentrate on a task without becoming distracted. Most educators and psychologists agree that the ability to focus one's attention on a task is crucial for the achievement of one's goals....
- Poor working memoryWorking memoryWorking memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
- Poor short term memory
- Difficulty in planning and reasoning
- Environmental dependence syndromeEnvironmental dependence syndromeEnvironmental dependency syndrome is a syndrome where the affected individual relies on environmental cues in order to accomplish goals or tasks. It is a disorder in personal autonomy that is influenced by individual psychological traits and can be helped through the intervention of other people...
Emotional symptoms
- Difficulty in inhibiting emotions, anger, excitement, sadness etc...
- DepressionDepression (mood)Depression is a state of low mood and aversion to activity that can affect a person's thoughts, behaviour, feelings and physical well-being. Depressed people may feel sad, anxious, empty, hopeless, helpless, worthless, guilty, irritable, or restless...
, possibly due to above. - Occasionally, difficulty in understanding others' points of view, leading to anger and frustration.
Behavioural symptoms
- Utilization behaviour
- PerseverationPerseverationPerseveration is the repetition of a particular response, such as a word, phrase, or gesture, despite the absence or cessation of a stimulus, usually caused by brain injury or other organic disorder. If an issue has been fully explored and discussed to a point of resolution, it is not uncommon for...
behaviour - Inappropriate aggression
- Inappropriate sexual behaviour
- Inappropriate humour and telling of pointless and boring stories (WitzelsuchtWitzelsuchtWitzelsucht, from the German witzeln, meaning to joke or wisecrack, and sucht meaning addiction or yearning, is a set of rare neurological symptoms characterized by the patient's uncontrollable tendency to make puns, tell inappropriate jokes and pointless or irrelevant stories at inconvenient moments...
)
Phineas Gage
Phineas Gage
Phineas P. Gage was an American railroad construction foreman now remembered for his improbablesurvival of an accident in which a large iron rod was driven completely through his head, destroying much of his brain's left frontal lobe, and for that injury's reported effects on his personality and...
, who suffered a severe frontal lobe injury in 1848, has been called a case of dysexecutive syndrome. But Gage's psychological changes are typically grossly exaggerated: of the symptoms listed above, the only ones Gage can even arguably be said to have exhibited (based on primary sources) are "anger and frustration," slight memory impairment, and "difficulty in planning".
In particular, the primary sources do not report utilisation behaviour, depression, aggression
Aggression
In psychology, as well as other social and behavioral sciences, aggression refers to behavior between members of the same species that is intended to cause humiliation, pain, or harm. Ferguson and Beaver defined aggressive behavior as "Behavior which is intended to increase the social dominance of...
, inappropriate sexual behaviour, or "inappropriate humour and telling of pointless and boring stories" (in fact, his audience was said to have found his stories entertaining). The oft-quoted statement by friends—that after the accident he was "no longer Gage"—admits interpretation as any number of behavioural or personality changes, not even necessarily of organic etiology. Although he was not able to return to his work for the railroad, after his physical recovery he was socially functional and self-supporting for the remainder of his life.
Head trauma
Closed head injuries, for example from motor vehicleMotor vehicle
A motor vehicle or road vehicle is a self-propelled wheeled vehicle that does not operate on rails, such as trains or trolleys. The vehicle propulsion is provided by an engine or motor, usually by an internal combustion engine, or an electric motor, or some combination of the two, such as hybrid...
accidents, can cause damage to the orbitofrontal cortex. Pre-frontal lobotomies severing connections between the pre-frontal cortex and the rest of the brain, were effectively a form of iatrogenic trauma resulting in a frontal lobe syndrome.
Cerebrovascular disease
Cerebrovascular diseaseCerebrovascular disease
Cerebrovascular disease is a group of brain dysfunctions related to disease of the blood vessels supplying the brain. Hypertension is the most important cause; it damages the blood vessel lining, endothelium, exposing the underlying collagen where platelets aggregate to initiate a repairing process...
may cause a stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
in the frontal lobe.
Degenerative diseases
Frontal lobe impairment is a feature of Alzheimer's diseaseAlzheimer's disease
Alzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death...
, frontotemporal dementia
Frontotemporal dementia
Frontotemporal dementia is a clinical syndrome caused by degeneration of the frontal lobe of the brain and may extend back to the temporal lobe...
and Pick's disease
Pick's disease
Pick's disease, is a rare neurodegenerative disease that causes progressive destruction of nerve cells in the brain. Symptoms include loss of speech , and dementia. While some of the symptoms can initially be alleviated, the disease progresses and patients often die within two to ten years...
.
Psychiatric disorders
There is evidence for frontal lobe impairment in schizophreniaSchizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
, depression, attention-deficit hyperactivity disorder
Attention-deficit hyperactivity disorder
Attention deficit hyperactivity disorder is a developmental disorder. It is primarily characterized by "the co-existence of attentional problems and hyperactivity, with each behavior occurring infrequently alone" and symptoms starting before seven years of age.ADHD is the most commonly studied and...
(ADHD), and antisocial personality disorder
Antisocial personality disorder
Antisocial personality disorder is described by the American Psychiatric Association's Diagnostic and Statistical Manual, fourth edition , as an Axis II personality disorder characterized by "...a pervasive pattern of disregard for, and violation of, the rights of others that begins in childhood...
or psychopathy
Psychopathy
Psychopathy is a mental disorder characterized primarily by a lack of empathy and remorse, shallow emotions, egocentricity, and deceptiveness. Psychopaths are highly prone to antisocial behavior and abusive treatment of others, and are very disproportionately responsible for violent crime...
.
A large number of studies have documented abnormalities in working memory in schizophrenia, associated with disrupted functioning of the dorso-lateral prefrontal cortex. There is also evidence for disruption of neuronal connections between the temporal
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
and frontal lobes in people with schizophrenia. The characteristic dorso-lateral prefrontal cortex morphological abnormalities are said to be related to a general impaired ability to control and regulate behaviour, which would correspond to deficits in several functional areas in schizophrenia. A study of people with schizophrenia using MRI scanning and psychological assessment has also found that longer duration of illness was associated with lower gray matter
Gray Matter
"Gray Matter" is a short story by Stephen King, first published in the October 1973 issue of Cavalier magazine, and later collected in King's 1978 collection Night Shift. It is set in the same area as King's novel Dreamcatcher.-Setting:...
volume in the left dorsomedial prefrontal cortex and the right middle frontal cortex, and these changes were associated with impaired working memory, attention and psychomotor speed. Another MRI study of schizophrenia has found an association between orbitofrontal cortex volume reduction and a longer duration of illness, impaired executive functioning, and greater formal thought disorder.
Research on children with ADHD has shown a general reduction of brain volume, but with a proportionally greater reduction in the volume of the left-sided prefrontal cortex. These findings are in keeping with the core ADHD features of inattention, hyperactivity, and impulsivity, but other brain regions have also been implicated in the causation of ADHD. The prefrontal cortex is also implicated by functional magnetic resonance imaging (fMRI) studies which examine brain activation during tasks such as motor response inhibition; reduced prefrontal cortex activation is associated with higher ADHD behavioural scores.
See also
- Frontal lobeFrontal lobeThe frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
- Executive functionsExecutive functionsThe executive system is a theorized cognitive system in psychology that controls and manages other cognitive processes. It is responsible for processes that are sometimes referred to as the executive function, executive functions, supervisory attentional system, or cognitive control...
- AttentionAttentionAttention is the cognitive process of paying attention to one aspect of the environment while ignoring others. Attention is one of the most intensely studied topics within psychology and cognitive neuroscience....
- Cognitive neuropsychologyCognitive neuropsychologyCognitive neuropsychology is a branch of cognitive psychology that aims to understand how the structure and function of the brain relates to specific psychological processes. It places a particular emphasis on studying the cognitive effects of brain injury or neurological illness with a view to...
- Working memoryWorking memoryWorking memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
- Phineas GagePhineas GagePhineas P. Gage was an American railroad construction foreman now remembered for his improbablesurvival of an accident in which a large iron rod was driven completely through his head, destroying much of his brain's left frontal lobe, and for that injury's reported effects on his personality and...