Encephale
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Case Reports
[Frontal dementia or dementia praecox? A case report of a psychotic disorder with a severe decline].
Many authors have described these last years the difficulty to establish a differential diagnosis between schizophrenia and frontotemporal dementia. However treatment and prognosis of these two separate diseases are not the same. Schizophrenia is a chronic syndrome with an early onset during teenage or young adulthood period and the major features consist of delirious ideas, hallucinations and psychic dissociation. However a large variety of different symptoms describes the disease and creates a heterogeneous entity. The diagnosis, exclusively defined by clinical signs, is then difficult and has led to the research of specific symptoms. These involve multiple psychological processes, such as perception (hallucinations), reality testing (delusions), thought processes (loose associations), feeling (flatness, inappropriate affect), behaviour (catatonia, disorganization), attention, concentration, motivation (avolition), and judgement. The characteristic symptoms of schizophrenia have often been conceptualised as falling into three broad categories including positive (hallucination, delision), negative (affective flattening, alogia, avolition) and disorganised (poor attention, disorganised speech and behaviour) symptoms. No single symptom is pathogonomonic of schizophrenia. These psychological and behavioural characteristics are associated with a variety of impairments in occupational or social functioning. Cognition impairments are also associated with schizophrenia. Since the original clinical description by Kraepelin and Bleuler, abnormalities in attentional, associative and volitional cognitive processes have been considered central features of schizophrenia. Long term memory deficits, attentional and executive dysfunctions are described in the neurocognitive profile of schizophrenic patients, with a large degree of severity. The pathophysiology of schizophrenia is not well known but may be better understood by neuronal dysfunctions rather than by a specific anatomical abnormality. Frontotemporal lobar degeneration (FTLD) is one of the most common causes of cortical dementia. FTLD is associated with an anatomical atrophy that can be generalised, with a frontotemporal or focal lobar predominance. Histologically there is severe neuronal loss, gliosis and a state of spongiosis. In a minority of case Pick cells and Pick bodies are also found. The usual clinical features of FTLD are divided in three prototypic syndromes: frontotemporal dementia (FTD), progressive non-fluent aphasia (PA) and semantic dementia (SD). FTD is the most common clinical manifestation of FTLD. FTD is first characterised by profound alteration in personality and social conduct, characterised by inertia and loss of volition or social disinhibition and distractibility. There is emotional blunting and loss of insight. Speech output is typically economical, leading ultimately to mutism, although a press of speech may be present in some overactive, disinhibited patients. Memory is relatively preserved in the early stage of the disease. Cognitive deficits occur in the domains of attention, planning and problems solving, whereas primary tools of language, perception and spatial functions are well preserved. PA is an initial disorder of expressive language, characterised by effortful speech production, phonologic and grammatical errors. Difficulties in reading and writing also occur but understanding of word meaning is relatively well preserved. In SD a severe naming and word comprehension impairment occur on the beginning in the context of fluent, effortless, and grammatical speech output. There is also an inability to recognise the meaning of visual percepts. The clinical syndromes of FTLD are associated with the brain topography of the degeneration. So considerable clinical overlap can exist between schizophrenia and FTLD and the object of the following case report is to remind the difficulty to make a differential diagnosis between these two pathologies. ⋯ A differential diagnosis between schizophrenia and FTLD is difficult to establish. Schizophrenia is a heterogeneous disease with a large variety of cognitive dysfunctions. Neurocognitive tools may improve our knowledge of schizophrenia.