It is essential to tell apart Alzheimer's disease from other similar conditions. This can be a challenge sometimes. There is not an accurate test, except for measures of regional cerebral glucose metabolism using PET scanning, to identify the early phases of dementia. The clinician is left with his skills of evaluation that depends on the patient's history, a physical examination, and laboratory tests.
The history provides important information, and several informants should be sought for corroboration. Even with the most thorough evaluation, diagnostic errors do occur.
Clinical diagnosis has an accuracy rates ranging from 65 percent to more than 90 percent, even though some other progressive dementias can rarely be distinguished on clinical grounds alone.
Vascular dementia is estimated to account for 10 to 20 percent of the dementias of old age. We differentiate vascular dementia from Alzheimer's disease by the sudden appearance of signs of illness and stepwise decline in cognitive functions: symptoms may be stable for a long period before another episode of deterioration. There will be also history of hypertension, blood clots, mini-strokes and localized motor or sensory defects in Multi-infarct dementia or vascular dementia. This is not error proof, as one third of al dementia is a mixed form of Alzheimer's disease and vascular dementia.
The main features that distinguish vascular dementia are:
Frontotemporal dementia is characterized by marked personality changes, less deterioration visuospatial skills like identifying person, places or finding the way around. Executive function like planning an action are also relatively preserved.
By contrast, patients with dementia with Lewy bodies show evidence visual hallucinations, delusions, fluctuating mental status, and sensitivity to antipsychotic drugs.
Alcohol and drugs may cause memory loss and other symptoms of dementia. For elderly patients, drugs may cause of memory impairment. This is of particular signficance as many elderly individuals are prescribed more than one drug for multiple physical ailments. Widespread use of more than one drug and the changes in body functions in old age make this group of patient more sensitive to side-effects of prescribed medicines. An elderly person's brain can be extremely sensitive to change in its environment, and almost any physical illness can effect such a change and can produce a dementia-like syndrome.
Several treatable physical and mental conditions must be considered before the diagnosis of dementia is confirmed.
Many prescribed drugs have anticholinergic effect as they block the action of Acetyle Choline in the body and inside the brain. Some are used for abdominal problems, or in mental health conditions. In dementia, psychiatric medication for anxiety, depression, mania or delusion may have an anticholinergic effect. They may not calm the patient as intended. They may make his behaviour less manageable, as the side effects make his dementia symptoms worse.
Medication used for hypertension, heart conditions, inflammation of the joints may also affect the symptos of dementia. Hormonal disturbances like thyroid hormones disease, and kidney or liver failures may cause worsening of dementia. Disturbance in blood electrolytes, sodium, and dehydration, or even constipation can affect the patient's condition. Poor hearing or vision in an elderly make the situation worse, so corrective measures may be helpful. Change from a familiar environment, like transfer from home to hospital, can cause more confusion and worsening of symptoms in dementia.
Depression in old age may mimic dementia. Dementia syndrome of depression is real and may be mistaken for Alzheimer's disease. Five to Fifteen percent of patients diagnosed with dementia may be mainly depressed. In the dementia syndrome of depression, patients complain od memory difficulty more than the actual memory loss observed on psychological testing. Slowness and lack of energy, poor concentration and lack of interest may be mistaken for cognitive impairment. A third of dementia patients may have both depression and dementia at the same time. This male the diagnosis more difficult.
There is evidence of age-related memory problems. Many people, starting from their 50s, may complain of loss or mild difficulties with their memory compared to what they have been as young adults. This condition may be more prominent as they age further. Age-associated memory impairment is seen in 40 percent of people in their 50s, which increases to 85 percent of those aged 80 years or older. However, the condition is stable over many years and reflect nomal aging. It does not progress to dementia, although many older people worry about this kind of forgetfulness. It may take them longer to recall information, but at the end they can regain well what they have already learned and remember important events from the past .