Diagnostic criteria The following diagnosis criteria were defined by Mesulam: * As opposed to having followed trauma to the brain, a patient must show an insidious onset and a gradual progression of<unk> , defined as a disorder of sentence and/or word usage, affecting the production and comprehension of speech. * The disorder in question must be the only determinant on functional impairment in the activities of the patient’s daily living. * On the basis of diagnostic procedures, the disorder in question must be unequivocally attributed to a neurodegenerative process. Whether or not<unk>  and other<unk> s are the only source of cognitive impairment in a patient is often difficult to assess because: 1) as with other neurologically degenerative diseases, such as Alzheimer's disease, there are currently no reliable non-invasive diagnostic tests for<unk> s, and thus neuropsychological assessments are the only tool physicians have for diagnosing patients; and 2)<unk> s often affect other, non-language portions of these neuropsychological tests, such as those specific for memory. Classification In 2011, the classification of<unk>  was updated to include three clinical variants. Patients must first be diagnosed with<unk> , and then divided into variants based on speech production features, repetition, single- word and syntax comprehension, confrontation naming, semantic knowledge, and reading/spelling. In the classical Mesulam criteria for<unk> , there are two variants: a non-fluent type<unk>  nonfluent<unk>  (PNFA) and a fluent type semantic dementia (SD). A third variant of<unk> , logopenic<unk><unk>  (LPA) was then added, and is an atypical form of Alzheimer's disease. For PNFA, The core criteria for diagnosis includes agrammatism and slow, and labored speech. Inconsistent speech sound errors are also very common, including distortions, deletions, and insertions. In terms of comprehension, there are deficits in syntax and sentence comprehension due to grammatical complexity, but single- word and object comprehension is relatively maintained. The second variant, SD, presents with deficits in single-word and object comprehension. Naming impairments can be severe, specially for low-frequency objects, and can eventually lead to a more widespread semantic memory deficiency over time. The ability to read and write can also be impaired if there are irregularities between pronunciation and spelling. However, repetition and motor speech is relatively preserved. The logopenic variant involves impairments in word retrieval, sentence repetition, and phonological paraphasias, comparable to conduction<unk> . Compared to the semantic variant, single word comprehension and naming is spared, however, sentence comprehension presents difficulty because of length and grammatical complexity. Speech will include incomplete words, hesitations preceding content words, and repetition. However, these<unk>  subtypes differ from similar<unk> s, as these subtypes do not occur acutely following trauma to the brain, such as following a stroke, due to differing functional and structural neuroanatomical patterns of involvement and the<unk>  nature of the disease.
Primary progressive aphasia
Logopenic progressive aphasia
Olive quick decline syndrome
Multiple system atrophy
Dysthanasia
Paroniria
Progressive supranuclear palsy
Semantic dementia