Frontal lobology--psychiatry's new pseudoscience

Executive function and adult homelessness, true impairment or frontal lobology?

Homelessness is associated with multiple risk factors for neurocognitive impairment. Past research with people experiencing homelessness has described "frontal lobe" dysfunction including behavioral disorders and executive cognitive impairments. In the current study, 72 adults experiencing homelessness were assessed with a standardized assessment of executive function, and interviewed regarding neurological and psychiatric history. When compared to a control sample of 25 never-homeless participants, and controlling for level of education, there was little evidence for executive dysfunction in the sample of people experiencing homelessness. Levels of substance abuse, past head injury, and post-traumatic stress disorder were notably high. However, there were no statistically significant associations between cognitive task performance and clinical or substance abuse variables. Gambling was surprisingly infrequent, but risk-taking behavior among intravenous drug users was common. Though in neither case was it linked to executive function. Overall, there was little evidence for executive impairment in this sample of people experiencing homelessness. I suggest that past research has often used inappropriate criteria for "normal" performance, particularly comparing people experiencing homelessness to control data of relatively high education level. This has led to elements of "frontal lobology," that is, clinical neuroscience research that tends to overly link non-typical or pathological behavior to frontal lobe impairment. When appropriate comparisons are made, controlling for education level, as in this study, associations between executive function impairments and adult homelessness may be weaker than previously reported.

Executive function of the brain and its influences on understanding of physics concept

Advances in neuroscience studies have brought new insights into the development of Executive Functions (EFs) of the brain and its influence on understanding science concepts. This study was conducted to examine the relationships between three main components of EF: working memory, inhibition, set-shifting and understanding of Force concepts among adolescents. This study also investigated how gender mediates the relationships between the components of EF and understanding. Cambridge Neuropsychological Test Automated Battery was used to assess students' level of working memory, inhibition, and set-shifting. The Force Concept Test measured students understanding. Smart-PLS analysis was employed to examine the relationships between the three components of EF and understanding; and how gender mediates the relationships. The result reveals that working memory significantly relates to students' understanding of Force concepts in a positive direction. On the contrary, both set-shifting and inhibition exhibit non-significant relationships. The findings also demonstrate that gender does not significantly mediate the relationships. The findings are useful for Physics teachers to guide them through designing the curriculum and opting for an appropriate pedagogical strategy considering the role of the components of EF for teaching the lessons on Force.

Identification of neuromotor deficits common to autism spectrum disorder and attention deficit/hyperactivity disorder, and imitation deficits specific to autism spectrum disorder

Deficits in motor and imitation abilities are a core finding in autism spectrum disorders (ASD), but impaired motor functions are also found in attention deficit/hyperactivity disorder (ADHD). Given recent theorising about potential aetiological overlap between the two disorders, the present study aimed to assess difficulties in motor performance and imitation of facial movements and meaningless gestures in a sample of 24 ADHD patients, 22 patients with ASD, and 20 typically developing children, matched for age (6-13 years) and similar in IQ (>80). Furthermore, we explored the impact of comorbid ADHD symptoms on motor and imitation performance in the ASD sample and the interrelationships between the two groups of variables in the clinical groups separately. The results show motor dysfunction was common to both disorders, but imitation deficits were specific to ASD. Together with the pattern of interrelated motor and imitation abilities, which we found exclusively in the ASD group, our findings suggest complex phenotypic, and possibly aetiological, relationships between the two neurodevelopmental conditions.

The assessment of neuropsychological functioning in schizophrenia

Overwhelming evidence suggests that compromised neuropsychological function is frequently observed in schizophrenia. The neuropsychological profile is typically characterized by prominent specific deficits in memory and learning, working memory, executive functions, attention, and processing speed, which are evident on a background of a generalized cognitive deficit This paper provides a review of studies of neuropsychological functioning in schizophrenia. The main cognitive ability areas affected in schizophrenia are described, and the degree of impairment in each ability area as found in studies of schizophrenia patients is summarized, based on meta-analytic findings. Recent studies that have compared neuropsychological functioning across psychotic disorders are presented, and finally, neuropsychological assessment batteries specifically developed for schizophrenia are introduced.

A Meta-Analytic Review of Verbal Fluency Deficits in Depression

A prominent view in the neuropsychological literature is that depression is particularly associated with deficits in executive control processes. A meta-analysis of 42 studies with 2306 participants was therefore conducted to investigate the sensitivity of tests of verbal fluency to the pressure of this disorder, as there is a great deal of evidence that theses measures are valid markers of executive dysfunction. When the methodology adopted by other meta-analytic reviews was employed, semantic fluency deficits were found to be substantially larger than the phonemic fluency deficits. However, when a more rigorous method of meta-analysis was adopted, this indicated that the measure are in fact broadly equivalent in their sensitivity to depression, as has been found for patients with focal frontal lobe lesions. However, in contrast to patients with focal frontal lobe injuries, neither deficit qualified as a differential deficit relative to psychomotor speed. Therefore, for patients with depression, deficits on tests of phonemic and semantic fluency may not reflect executive dysfunction, but a more generalized impairment. Evidence is presented that tests of phonemic and semantic fluency may aid in the differential diagnosis of patients with depression and those in the early stages of dementia of the Alzheimer's type.

Disease, deficit or denial? Models of poor insight in psychosis

OBJECTIVE

To examine the evidence for the three kinds of aetiological model that dominate the current literature on poor insight in psychosis: clinical models, the neuropsychological model, and the psychological denial model.

METHOD

Studies pertaining to one or more of these aetiological models were identified, reviewed and critically evaluated.

RESULTS

There is little support for clinical models, partly because they lack testable hypotheses. Several studies reveal a positive relationship between insight and executive function, which may be related to frontal lobe dysfunction. However, the extent to which this relationship is specific and independent of general cognitive impairment remains unclear. There is tentative evidence to support the psychological denial model. Recent data combining the latter two approaches suggest that multiple factors contribute to poor insight.

CONCLUSION

Integration of different aetiological models is necessary for a fuller understanding of insight in psychosis. Future research should assess multiple aetiological mechanisms in single investigations.

Impaired Trail-Making Test-B performance in patients with acute schizophrenia is related to inefficient sequencing of planning and acting

In order to investigate the functional basis of the frequently described deficits of schizophrenia patients in Trail Making Test B (TMT-B) performance, the performance process was analyzed based on the interaction of eye and hand movements. In a longitudinal design, 23 acute schizophrenia patients, 17 acute depressive inpatients, and 21 healthy controls were assessed twice within 4 weeks. Computer versions of both TMT-A and TMT-B were used, which require to connect different targets with a cursor, with concurrent infrared oculography. In both TMT-versions, schizophrenia patients demonstrated poorer performance and longer "planning periods"--as defined by fixations outside the cursor area--containing more fixations, which were stable over time. However, these "planning fixations" were only also longer in duration during TMT-B and differed in time and context of their occurrence compared with healthy controls. Schizophrenia patients demonstrated more fixations while the cursor rested between targets. Significant correlations with performance time gave evidence that it is important for short planning periods to be performed parallel to ongoing connection of targets, to obtain a satisfactory result. No relationship between "planning variables" with psychopathology and medication could be found. Accordingly, poorer TMT-B performance in schizophrenia patients was found to be related to insufficient sequencing of planning and acting, which appears to be a trait-like characteristic. Though depressive patients also performed poorer in TMT-B, they did not differ from either of the other groups in the main process variables, which may hint to different underlying causes of the performance deficits in both groups of patients.

Comparison of heteronymous monosynaptic Ia facilitation in young and elderly subjects in supine and standing positions

BACKGROUND

The control of posture and balance is a primary concern among the elderly. Postural instability has been identified as a contributor to the greater incidence of falling among this segment of the population. One important neuromuscular mechanism identified as important in the control of posture and balance is the segmental reflex system. The purpose of this study was to examine the role of presynaptic inhibition in modulating the reflex system in young and elderly subjects.

METHODS

To estimate the influence of body position on presynaptic inhibition to the soleus motor pool between young and elderly subjects, 11 young (mean age=23.9 yrs.) and 9 elderly (mean age=72.1 yrs.) subjects were examined in two different body positions: supine and standing. This study utilized the heteronymous facilitation protocol, as described by Hultborn et al. (1987), to estimate presynaptic inhibition of the Ia afferent pathway onto the soleus alpha-motoneuron pool. Maximal soleus H-reflex (H-max) and motor response (M-max) amplitudes were determined prior to testing at each condition, and the H-max/M-max ratio at each body position was determined. To estimate presynaptic inhibition at each body position, subjects received 24 test soleus H-reflex stimuli ( approximately 15% M-max), and 24 soleus H-reflexes conditioned by stimulation of the ipsilateral femoral nerve.

RESULTS

Results demonstrated a significant decrease in H-max/M-max ratio from supine (66.1%) to standing (56.8%) for the young subjects, whereas the elderly subjects demonstrated no changes in the H-max/M-max ratio between body positions (39.8% supine; 39.8% standing). The conditioning stimulus produced a significant change in the test reflex for the young subjects during supine testing (51.1% increase) but not standing (3.4% increase). The elderly subjects demonstrated no significant changes in the test reflex produced by the heteronymous conditioning at either condition (17.6% increase supine; 4.9% increase standing).

CONCLUSIONS

These results demonstrate differential effects of both H-reflex modulation and heteronymous conditioning for elderly subjects when compared with young adults. These differences may be an adaptive phenomenon of the aging neuromuscular system, exemplified by a decreased ability to modulate the reflex system in the elderly group.

"To see oursels as others see us". Aubrey Lewis's insight

BACKGROUND

This paper takes as its starting point the paper by Aubrey Lewis entitled "The psychopathology of insight" published in 1934, unreferenced.

AIMS

To attempt to explore the historical antecedents and consequences of this work.

METHOD

Speculative review.

RESULTS

Lewis's approach to phenomenology, contemporaneous movements in psychology and Lewis's own life and times--notably the eugenics legislation in Nazi Germany--probably shaped his conclusions. Modern concepts of insight, which emphasise neuropsychology as well as social psychology, were anticipated in Lewis's writings.

CONCLUSIONS

The concept of insight has stimulated research into difficult theoretical and practical areas such as self-awareness and treatment compliance, respectively. Concern over a patient's capacity for insight has the potential to humanise psychiatry.

A meta-analytic review of Wisconsin Card Sort studies in schizophrenia: general intellectual deficit in disguise?

A majority of studies show that schizophrenics perform poorly on so-called tests of executive or frontal lobe function--the paradigmatic case being the Wisconsin Card Sort Test (WCST). Nevertheless, the specific character of this deficit in schizophrenia remains underspecified. In particular, it seems premature to assume that schizophrenia is characterised by an executive dysfunction and/or a disorder of frontal lobe function before determining whether any deficit is: selective; disproportionate to the general level of intellectual functioning; or qualitatively comparable with that of frontal lobe patients. A meta-analysis was conducted on 29 studies comparing the performance of schizophrenics and normal controls on the WCST. This showed that the mean weighted effect size was large for categories achieved (d = 0.91), medium for absolute level of perseveration (d = 0.53), but only small for the proportion of perseverative errors (d = 0.18). By contrast, the effect size for Wechsler Adult Intelligence Scale Intelligence Quotient (WAIS IQ) in a subset of these studies (d = 1.23) was significantly larger than for any WCST measures. This pattern of findings challenges notions that schizophrenia is characterised by an executive dysfunction that is: selective; disproportionate to IQ level; and analogous to that found in frontal lobe patients. Rather, the poor WCST performance of schizophrenics appears to reflect a generalised intellectual deficit.

Low frontal electroencephalographic coherence in neuroleptic-free schizophrenic patients

BACKGROUND

Electroencephalographic (EEG) coherence analysis is a noninvasive technique for studying corticocortical associations. As there is evidence for a dysfunction of the prefrontal dorsolateral cortex in schizophrenia, we hypothesized to find lower frontal EEG coherence in schizophrenia.

METHODS

EEG amplitude and coherence analysis was performed in 16 antipsychotic-free schizophrenic patients and 16 healthy controls. EEG recordings were done with 19 gold-plated electrodes placed according to the International 10/20 system against averaged signals from both earlobes. Local coherence was computed for 22 adjacent electrode pairs within the hemispheres and interhemispheric coherence for eight corresponding electrode pairs of both hemispheres in the delta, theta, alpha, and beta-I band.

RESULTS

Amplitude and interhemispheric coherence analysis revealed no differences. Local EEG coherence was significantly lower in schizophrenic patients for Fpl-F7 in the delta (p = .001) and the theta band (p = .002), and at F7-F3 in the alpha band (p = .002). In the delta band coherence of Fpl-F7 was inversely correlated to the Positive and Negative Syndrome Scale positive symptoms subscore (R = -.74, p = .014).

CONCLUSIONS

Assuming that EEG coherence can be used to index functional coupling between brain areas under the electrodes, the low EEG coherence in Fpl-F7 and F7-F3 in schizophrenic patients might reflect impaired information processing in the left dorsolateral prefrontal cortex.

Functional connectivity in depressive, obsessive-compulsive, and schizophrenic disorders: an explorative correlational analysis of regional cerebral metabolism

In order to investigate the changes in functional relationships between brain regions in three psychiatric disorders, an exploratory statistical analysis of the regional cerebral metabolic rates for glucose (rCMRglu) obtained with positron emission tomography (PET) was performed. Correlations between various rCMRglu were computed in control, depressive, obsessive-compulsive, and schizophrenic groups to determine whether alterations of the correlation pattern were found in the psychiatric groups. The absence of correlation between left and right frontal lobes was common to the three psychiatric groups studied. Depressive patients recovered a better frontal interhemispheric coupling after successful treatment and the alterations in the depressed state also involved the relation between the right temporal cortex and the right thalamus. Obsessive-compulsive patients had not only lateral frontal dysfunction but also alterations in the functional relationships between cortex and thalami. In schizophrenic patients, the modifications of regional cerebral metabolic correlations involved both anterior and posterior cortical regions. Thus, although the relationship between left and right frontal lobes was altered in three psychiatric disorders, the pattern of functional connectivity between frontal regions, posterior cortical and subcortical regions differed depending on the diagnostic group.

Executive deficits in major depression

Clinically depressed patients and control subjects were examined by means of different tests to assess executive functions (the Wisconsin Card Sorting Test, the Stroop Color Word Test and a test of verbal fluency). The results indicate that the depressed patients were generally slower than the controls, as reflected by longer retrieval times for both words and colours. Furthermore, the depressed patients showed impairment with regard to altering behaviour appropriately in response to feedback. However, there were no depression-related increases in perseverative responses, and the ability to inhibit irrelevant information was unaffected by depression. No relationship was found between specific depressive symptoms or the severity of depression and cognitive performance. The overall pattern of results suggests that depression may affect various executive functions in a differentiated manner.

Variables that influence the generation of random sequences: an update

This article updates Tune's 1964 review of variables influencing human subjects' attempts at generating random sequences of alternatives. It also covers aspects not included in the original review such as randomization behavior by patients with neurological and psychiatric disorders. Relevant work from animal research (spontaneous alternation paradigm) is considered as well. It is conjectured that Tune's explanation of sequential nonrandomness in terms of a limited capacity of short-term memory can no longer be maintained. Rather, interdependence among consecutive choices is considered a consequence of an organism's natural susceptibility to interference. Random generation is thus a complex action which demands complete suppression of any rule-governed behavior. It possibly relies on functions of the frontal lobes but cannot otherwise be "localized" to restricted regions of the brain. Possible developments in the field are briefly discussed, both with respect to basic experiments regarding the nature of behavioral nonrandomness and to potential applications of random-generation tasks.

Executive functions and disease characteristics in Parkinson's disease

In the present study, we investigated the association of two executive functions with disease characteristics in Parkinson's disease (PD), especially with severity of motor symptoms. We operationalized two executive functions, viz. fluency and cognitive shifting, each in a number of tests with heterogeneous materials, but with an identical format. We calculated the correlations between test performance and disease characteristics, including the factor scores of the Unified Parkinson's Disease Rating Scale (UPDRS). The results of this study show that only cognitive shifting was consistently associated with the severity of motor symptoms in PD, in particular with rigidity. None of the fluency tests had a significant association with severity of motor symptoms. The present study indicates that PD, as reflected by the severity of motor symptoms, is not associated with a general decrease in executive function. In spite of the fact that both are executive functions and both require generation of items, fluency and cognitive shifting are differentially related to PD.

Functional lateralization of the prefrontal cortex during traditional frontal lobe tasks

We attempted to identify brain regions functionally lateralized during cognitive tasks traditionally linked to the prefrontal cortex (PFC) by measuring regional cerebral blood flow with H2(15)O positron emission tomography (PET). Fourteen normal subjects were scanned six times while performing six different cognitive conditions comprising three task paradigms putatively sensitive to PFC integrity: the Wisconsin Card Sort (WCS), Delayed Response Alternation (DA), and the Spatial Delayed Response (SDR) Tasks, and three matched sensorimotor control tasks. Multivariate and repeated measures analyses indicated that for all three cognitive paradigms there were no significant hemisphere, hemisphere-by-condition, or hemisphere-by-region effects. However, with more liberal statistical comparison (paired t tests), the superior frontal gyrus showed lateralization during both the WCS and SDR tasks (both R > L). These results suggest that, although some asymmetries may be found using liberal analyses, there is less evidence of lateralized brain function during performance of these tasks of PFC function, than in language and motor systems. Implications for testing PFC function in neuropsychiatric groups are discussed.

A spectrum for obsession and personality disorders

Obsession was introduced by Kraepelin in 1915 and has been studied extensively since. When a person with obsession becomes physically exhausted with chronic rumination accompanied by suspicion, he or she is driven to impulsive acts, and develops a personality disorder that displays persistent abnormal activities. Obsession is related closely to depression and schizophrenia. Obsession is induced when uncertainty and instability dominates intelligence and creativity. The current social hierarchy of a strongly controlled society rejects diversity of humanity and often triggers personality disorders. This article reviews obsession and a myth as primitive mentality, normal and abnormal obsession, obsession vs possession, society and obsession/ impulsion/degeneration, obsession and slowness/autism, a recent biological approach to obsession and a spectrum for obsession.

Cognitive flexibility and complex integration in Parkinson's disease, Huntington's disease, and schizophrenia

Two new tasks designed to individualize and assess aspects of cognitive flexibility and complex integration were administered to patients with schizophrenia (n = 16), Parkinson's disease (PD; n = 25) and Huntington's disease (HD; n = 12). Findings indicated impaired performance in the schizophrenic and HD groups on components of solution fluency, reactive flexibility and integration. The PD group demonstrated normal performance on all but the solution fluency and reaction time measures. These findings corroborate previous studies suggesting that executive and problem solving disturbances feature in schizophrenia and HD and that these functions may not be as severely affected in medicated PD. Slowed reaction time by both dementia groups is explained with reference to the concept of bradyphrenia.

Neuropsychological and olfactory dysfunction in schizophrenia: relationship of frontal syndromes to syndromes of schizophrenia

Behavioural changes and cognitive impairments in schizophrenia have been linked to disturbances of complex neural networks involving both frontal and subcortical systems. Current literature has emphasised the role of the dorso-lateral prefrontal cortex (DLPFC) and its connections with hippocampus in the pathogenesis of schizophrenia. Based on a review of the literature, this paper examines other possible prefrontal areas that contribute to the manifestations of schizophrenia. We focus on the orbito-frontal cortex (OFC) and argue that it also plays an important role in the behavioural manifestations, symptoms and cognitive impairments observed in schizophrenia. The importance of fronto-striato-thalamic circuits connecting these prefrontal sites with subcortical structures is examined and the relevance of functions specific to these circuits or their components are briefly discussed. The subdivision of the functions of the prefrontal cortex into 'prefrontal' syndromes are examined and related to both the behavioural and symptom-based syndromes of schizophrenia. Possible dissociations of function of the various prefrontal syndromes and the relationship of these to schizophrenia syndromes may provide clues to the underlying neurobiology of schizophrenia. The use of tasks deemed specific to DLPFC and OFC networks may be useful as probes to examine the integrity of these circuits. We discuss such 'circuit-specific' tasks including delayed response, delayed alternation and object alternation tasks derived from the animal literature and other tasks such as olfactory identification ability. This approach raises the possibility that a number of prefrontal cortical areas and their subcortical connections are important in accounting for the heterogeneity of schizophrenia.

Some methodological issues in neuroradiological research in psychiatry

An outline is given of some of the methodological issues discussed in neuroradiological research on psychiatric illness. Strengths and shortcomings of magnetic resonance imaging (MRI) in depicting and quantifying brain structures are described. Temporal lobe anatomy and pathology are easily accessible to MRI, whereas limits on anatomical delineation hamper approaches to frontal lobe study. White matter hyperintense lesions are sensitively depicted by MRI, but specificity is limited. Distinction of vascular and primary degenerative dementia is considerably improved by CT and MRI analysis. Computed tomography (CT) and MRI have enhanced the understanding of treatable organic psychiatric disorders, e.g., normal pressure hydrocephalus. Subcortical and white matter pathology has been replicated in CT and MRI studies of late-onset psychiatric disorders, clinical overlap with cerebrovascular disease or neurodegeneration may be of import. Transcranial sonography findings of brainstem structural change specific to unipolar depression may contribute to the understanding of affective psychoses. Magnetic resonance spectroscopy and functional MRI are likely to stimulate psychiatric research in the future.

Time course of prefrontal lobe dysfunction in severely depressed in-patients: a longitudinal neuropsychological study

The Stroop Colour-Word Test (SCWT) and the Verbal Fluency Test (VFT), two tests that have been suggested to be particularly sensitive to prefrontal dysfunction, were administered to 23 severely depressed in-patients. Both tests were impaired in patients at inclusion, but only verbal fluency normalized with successful treatment of depression. VFT impairment is consistent with the hypothesis of a left prefrontal cortex dysfunction in depression. Moreover, the persistence of an impaired performance on SCWT in patients at discharge suggests that a selective attention deficit may persist in patients beyond a clear clinical improvement.

Psychotic speech: a neurolinguistic perspective

The existence of an aphasia-like language disorder in psychotic speech has been the subject of much debate. This paper argues that a discrete language disorder could be an important cause of the disturbance seen in psychotic speech. A review is presented of classical clinical descriptions and experimental studies that have explored the similarities between psychotic language impairment and aphasic speech. The paper proposes neurolinguistic tasks which may be used in future studies to elicit subtle language impairments in psychotic speech. The usefulness of a neurolinguistic model for further research in the aetiology and treatment of psychosis is discussed.

Bedside assessment of frontal degeneration: distinguishing Alzheimer's disease from non-Alzheimer's cortical dementia

Two instruments, the Executive Interview (EXIT) and the Qualitative Evaluation of Dementia (QED), that are useful in the evaluation of frontal system failure are discussed. The ability of these instruments to discriminate frontal-type dementia (FTD) from Alzheimer's disease (AD) and the dementia of major depression (DMD) was examined in 100 consecutive elderly dementia patients presenting to a multidisciplinary geriatric clinic. All groups showed executive impairment by the EXIT, and 46% of the FTD patients were found to be unimpaired by the Mini-Mental State Examination (MMSE). The AD and FTD groups differed significantly from the DMD group on the QED. The QED alone could not distinguish AD from FTD cases. However, mapping of EXIT scores against MMSE (errors) scores revealed that AD and FTD follow very different regression lines.

Cognitive functioning and anhedonia in subjects at risk for schizophrenia

This study investigated the performance of individuals with familiar loading of schizophrenia (healthy siblings of schizophrenic inpatients) on three neuropsychological tasks assumed to require frontal lobe functions: Trail Making Test (TMT), verbal fluency and Wisconsin Card Sorting Test (WCST). Healthy siblings of schizophrenics differed in performance from healthy controls not only on the WCST, but also on the Trail Making Test and the verbal fluency task. Furthermore, scores of physical anhedonia, assessed in a self-report rating scale (Chapman et al., 1976) were also significantly higher in the high risk group than in the control sample. However, healthy siblings of schizophrenics did not differ from controls with regard to experiences of perceptual aberrations, measured by the same method (Chapman et al., 1978). Neuropsychological performance and elevated anhedonia scores in the high risk group were interpreted under the conceptual framework of vulnerability markers: they were supposed to represent a trait shared by family members of schizophrenic probands. Amongst the neuropsychological tests, there were significant correlations between the physical anhedonia score and WCST and Trail Making test performance in the group of healthy siblings of schizophrenics, but not in the control group.

Frontotemporal Dementias: A New Clinical Syndrome?

The frontal lobe dementias (FLDs) are a group of disorders that have received considerable attention recently. Diagnosis is based on the presence of behavioral and cognitive disturbances associated pathologically with focal neuronal loss and gliosis without any inclusion bodies. Reports describing FLD differ regarding its clinical features, cognitive disturbances, and neurophysiological and neuropathological characteristics. The authors review the existing literature on FLD and emphasize the similarities and differences between reports. The heterogeneity of this condition as currently described is addressed, and arguments supporting the concept of FLD as a syndrome more appropriately called frontotemporal dementia are discussed. The authors present the development of a more rigid clinical definition of this syndrome using well-defined criteria as the first step toward understanding better this group of disorders.