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Dementia or Major Neurocognitive Disorder is a collective name for a group of progressive brain disorders that affect the ability to remember, think clearly, communicate and perform daily activities and frequently cause changes in mood, behaviour and personality.
Common symptoms of dementia include:
Even though dementia occurs primarily in people older than age 65, it is never a part of normal aging. As people age, they may experience some decline in memory - for example they may occasionally forget names or be slow to recall them, occasionally misplace items, have an occasional difficulty finding words or become slower in learning new things and have slight difficulty in recalling previously learnt information. These age-related changes unlike dementia, do not affect normal functioning. Dementia is a much more serious decline in cognitive abilities significantly impairing a person’s capacity to function independently. About 15 – 20% of patients with dementia are below the age of 65.
Dementia is not a pure psychological condition such as schizophrenia or bipolar disorder. It is a structural brain disease with additional psychiatric symptoms like depression, delusions, hallucinations, agitation and sleep problems arising at various stages.
Mild cognitive impairment [MCI] or Minor Neurocognitive Disorder is often but not always the pre-dementia state. In MCI, patients have memory and other cognitive impairments but are functioning normally to a great extent whereas in dementia the cognitive deficits are sufficiently severe to interfere with day-to-day functioning.
What is the relationship between dementia and depression?Depression can itself cause mild memory problems or it can accompany dementia. The pattern of memory impairment found in depression is distinct from that seen in Alzheimer’s disease. Depressed people with memory problems show an improvement in memory function after the depression is treated.
The common causes of dementia are the following:
In the majority of patients who develop dementia after the age of 65 years it is not a familial illness. However, a minority of patients developing dementia before the age of 65 years may have some form of familial dementia. Some of the genes identified in familial forms of dementia include ApoE Epsilon 4, Presenilin 1, 2 [for Alzheimer’s Disease], Notch 3 mutation [for CADASIL - a form of Vascular Dementia] and C9orf 72 [a form of Frontotemporal Dementia].
Alzheimer’s disease is characterized by the deposition of the harmful amyloid protein in the brain and starts in the medial parts of the temporal lobes. In Alzheimer’s disease the initial and the most prominent symptom is nearly always memory loss. Memory for recent events is the first to deteriorate while past memory continues to remain intact until the more advanced stages. They repeat questions and conversations and forget recent events or appointments. Subsequently as the illness progresses patients become confused about familiar people or objects, have problems finding and using the right word and may lose their way in familiar surroundings.
In Vascular dementia the initial memory loss might not be as severe as in Alzheimer’s disease and patients might have trouble concentrating, deciding and judging and completing a familiar task that involves multiple steps [like cooking]. They also may have symptoms of strokes that might have occurred at any time. These include paralysis on one side of the body, speech disturbances, walking difficulties and loss of balance. This type of dementia is due to various small or large strokes occurring in different parts of the brain.
In Parkinson’s disease dementia or Dementia with Lewy bodies the initial memory loss might be less severe, and patients have slowed thinking, fluctuating alertness/confusion, visual hallucinations, repeated falls and symptoms of Parkinsonism such as tremors, slowness and walking difficulty. These dementias result from deposition of the harmful protein called alpha synuclein in different parts of the brain.
In Frontotemporal dementia the memory loss is less severe and instead patients have prominent changes in personality and behaviour. They repeat words and actions, become excessively friendlier and tactless and do not care as much for personal hygiene and grooming. They may wander or pace restlessly and manifest changes in eating behaviour/food preference. It results from deposition of the harmful protein tau in the frontal and temporal lobes of the brain.
In Mixed dementia the clinical picture resembles Alzheimer’s disease but there is also MRI evidence for silent strokes or significant white matter hyperintensities. This might be the commonest cause of late onset dementia in the community as revealed by autopsy studies.
In Normal Pressure Hydrocephalus memory loss is milder and accompanied by slowed thinking. More importantly there are changes in walking and balance and changes in urination such as frequency, urgency or incontinence. It results from accumulation of excess cerebrospinal fluid in the ventricles of the brain.
Dementia is diagnosed by asking the primary caregiver certain questions. Then the person with suspected dementia is given a brief memory test. Doctors also look for clinical clues suggesting depression or neurological disease [Stroke, Parkinson’s disease or Normal Pressure Hydrocephalus] as a possible cause. Blood tests are done to rule out hypothyroidism or vitamin B 12 deficiency. A brain scan [CT or MRI] is performed to rule out a stroke or normal-pressure hydrocephalus. More detailed memory testing (called neuropsychological assessment) is sometimes needed to clarify the presence, pattern and extent of cognitive impairment. In some patients a Brain Radionuclide PET Scan or Cerebrospinal Fluid Analysis may be required to clarify the type of dementia.
For most dementias, no treatment can completely restore brain function.
Drugs: Currently available drugs like the cholinesterase inhibitor drugs donepezil, rivastigmine, galantamine and the NMDA receptor antagonist drug memantine may show symptomatic benefits and stabilize memory and other brain functions temporarily though not in all patients. Recently a new class of injectable drugs called monoclonal antibodies that target beta-amyloid in the brain have become available to treat early-stage Alzheimer’s disease. These drugs which include Aducanumab, Lecanemab and Donanemab, by removing beta-amyloid from the brain of Alzheimer’s disease patients, reduce cognitive and functional decline in people living with early-stage disease. Some herbal medicines like Brahmi/Bacopa Monniera, Mandukaparni/Centella Asiatica, or Ginkgo biloba may also give modest benefits. Mind-Body interventions such as meditation and Yoga have also been shown to improve or slow cognitive decline in both MCI and dementia and Yoga has also been shown to improve balance and stability in seniors with dementia thereby preventing falls. Antipsychotic drugs such as aripiprazole, olanzapine, quetiapine and risperidone are often used to control agitation, sleep problems, hallucinations or delusions that may occur in persons with dementia. Antidepressants are used to treat depression which can coexist with dementia. In addition to these drugs patients will also need to be treated for stroke or Parkinson’s disease if these have caused the dementia.
Surgery: Brain surgery in the form of a shunting procedure to divert the excess fluid accumulating in the brain is the treatment of choice in selected patients with Normal Pressure Hydrocephalus.
In people with dementia, brain function typically deteriorates over a period of 2 to 10 years. In the advanced stages of dementia patients become unable to speak or comprehend, unable to swallow food, incontinent of urine and feces and eventually bedridden. However, the rate of progression varies depending on the cause of dementia and from person to person.
Caring for people with dementia is physically and emotionally stressful. Caregivers should not abandon physical activity, hobbies and socialization. Joining a local caregiver support group would also be beneficial.
Almost 40 -50% of the risk of developing cognitive decline [MCI or dementia] can be mitigated by the following measures:
