Alzheimer’s Disease: Diseases Associated with Loss of Intellectual Functioning
Adam E. Waterbury
February 14, 2018
Alzheimer's Disease Alzheimer’s Disease (AD) is a progressive degenerative disease of
unknown aetiology, as first described by Alois Alzheimer (1907). According to Shoenberg et. al (1987), it is the commonest cause of dementia in the elderly with an incidence ranging from 2.5 to 5 per thousand. Furthermore, this incidence has grown in recent years as a result people generally living longer. The disease is incurable at present but there are drug treatments that delay the symptoms in the early stages. Therefore, there is a real need for early identification of the disease, so that a treatment program can be administered.
In the later stages of AD, there are typical neurological signs of the disease. These are plaques and tangles in the hippocampal region of the brain. However, it may be a while into the disease before these can be detected by diagnostic tools such as CT, MRI and fMRI. In addition, reliance on these tools can lead to a false diagnosis of AD, where some form of vascular dementia is actually the cause. In fact, according to Brazzelli et al. (1994), there is no unequivocal instrumental test to establish the presence of the disease. Therefore, it is also common practice to establish the neuropsychological symptoms of AD. Numerous studies have been conducted into the neuropsychiatric symptoms of AD so that diagnosis can be as accurate as possible.
According to Venneri, Turnbull and Sala (1996) the low contribution of neurological and neuroradiological examination to the diagnosis of AD in its early stages raises severe diagnostic problems. This is because up to 30 per cent of dementias may be curable (e.g. depressive psuedodementia, normotensive hydrocephalus) and the possible diagnosis of AD needs to be excluded for these to be treated. According to the ICD-10 other causes of dementia (such as CVD, Parkinsons, Corea, and Hydrocephalus) must be excluded before making a diagnosis of AD. The
ICD-10 diagnostic criterion for AD is verbal and non-verbal memory decline, decline of all other cognitive abilities, objective evaluation, environmental awareness, emotional weakness, irritability,
apathy and disorders of behaviour. A history of these symptoms proceeding at least 6 months must also be present. However, this is not the case with the DSM-IV. The DSM-IV criteria starts the same as the ICD-10 with memory impairment, then states one or more cognitive deficits (aphasia, apraxia, agnosia) must be present. On top of this, there must also be deficits in executive functions, deficits interfering with working and social activities, gradual changes compared with previous evaluations and slow progressive decline. As with the ICD-10, the DSM-IV also states that other causes of dementia must be excluded. These are the same as seen in the ICD-10 but also include additional causes s...