The disease has a very insidious onset and it progresses very gradually. It basically affects the emotion, intellect and memory of the person. It develops through 3 stages:
Stage 1
o The memory of the person is affected in the initial stages. First, impairment of memory for recent happenings can be noticed which is later followed by impairment of long term memory also.
o Patients themselves complain of the difficulty in the initial stages.
o The person also has disorientation of time and place; he misidentifies things and people.
o He repeats his words again and again.
Stage 2
o Here, the patient denies that anything is wrong with him says that he is alright.
o Gradually, the person shows deterioration of his intellectual functions and certain personality changes occur. He may also develop problems pertaining to speech language.
o He may later develop aphasic syndrome (Lack of right word at the right time compels the patient to compensate by speaking around the subject- àparaphasia-àimpoverished vocabulary- also that the patient can't convey his feelings due to fragmented words sentences -a mutism results.)
o Constructional apraxia (Inability to draw two or three dimensional figures.) follows.
o The person finds it difficult to wave his h to someone, greet someone or even to use a pen for writing.
o Visual agnosia develops (inability to comprehend what he sees).Due to these functional deficits, the person develops some psychiatric disturbances like: depression, aggression, anxiety, delusions, sleeplessness etc.
Stage 3
o Finally, the person reaches a stage when he has to depend on others for his daily living activities.
o The person may develop self care apraxias like: dressing, shaving, bathing, combing hair.
o Visual agnosia is followed by auditory, tactile agnosias.
o In these advanced stages, even the musculature is affected. The patient walks in a shuffling manner with short steps. Stiffness of all the muscles leads to slowness and awkwardness of all the movements. The entire course of the illness is 5-8 years approximately. During the course of the illness, any coexistent illness worsens the condition of the patient acutely.