D i.e. Alzheimer's disease Alzheimer's disease, the most common cause of dementiaQ initially presents with minor forgetfulness & gradually progressive sho term memory lossQ (making learning of new information difficult). Language is usually affected early with difficulty in finding words or naming objects, & impairments in the ability to construct fluent & informative sentences. The memory is lost for recent events first with a delayed loss of long term memory mainly affecting episodic memoryQ. It is a parieto temporal disease. Multi infarct (or vascular) dementia (or atherosclerotic psychosis), the 2,0 most common cause of dementia (not Alzheimer's disease) is caused by cerebro- vascular disease (ischemia or infarct)Q. It is characterized by an abrupt onset, acute exacerbations ((lit repeated infarcts), stepwise wise (step-ladder pattern) progressionQ (i.e. impairment of memory & intellect), fluctuating course (periods of deterioration f/b paial recovery for few months) and presence of hypeension (m.c.), cardiovascular disease & h/o previous stroke or transient ischemic attack. Lewy Body dementia, the 2,,d most common cause of degenerative dementia characteristically presents with progressive & fluctuating dementia (affecting cognition, attention & visuosptial ability), recurrent delirium like phase, systematized delusions, visual hallucinations (usually well formed & detailed), motor features of Parkinsonism (bradykinesia > tremor, rigidity), extra pyramidal symptoms, neuroleptic sensitivity syndrome (to antipsychotics)Q, together with repeated fallsQ, syncope, transient loss of consciousness, autonomic dysfunctions (eg. ohostatic hypotension) & urinary incontinence. It is (like Parkinson's disease) a ' synucleinpathy' reflecting abnormal aggregation of eosinophilic inclusion Lewy bodies (i.e. a synuclein & ubiquitin) in cytoplasm of neurons of neocoex & substantia nigra. Pick's disease (in contrast to parietal - temporal- Alzheimers ds,)Q is a prototype fronto- temporal dementia. It classically presents with insidious onset gradually progressive behavioural & personality changes (frontal lobe function) and language disorder (such as aphasia - left temporal lobe function) usually preceding or overshadowing patient's cognitive problems. Patients may show apathy (medial frontal damage), disinhibition (basal - frontal dysfunction), symptoms of kluver Bucy syndrome (i.e. hypersexuality, hyperorality, placidity, and a compulsion to attend to any visual stimulus) and loss of drive, motivation, insight and spontaneity of speech (frontal language). The striking pathological findings is Knife blade atrophy of frontal & temporal poles with Pick's cells (ballooned neurons) and Pick's inclusion body (irregular, silver staining, intracytoplasmic bodies composed of tau, ubiquitin etc that displace nucleus towards periphery). Fronto- temporal dementias include - Pick's disease, lobar atrophyQ, frontal lobe degeneration (non- Alzheimer's type), fronto temporal dementia with parkinsonism, motor neuron diseaseQ (MND) with dementia, semantic dementiaQ with aphasia & agnosia, progressive nonfluent aphasic syndromeQ. Sometimes (not always) coicobasal degeneration, progressive supranuclear palsy & parkinsonism dementia complex of Guam are also included.