Common symptoms include memory loss that disrupts daily life, difficulty in planning or making decisions, disorientation and confusion, and problems with speech and language. In more advanced stages, the patient may have trouble moving around or performing hygiene and self-care tasks. It is a chronic disease, which means the symptoms keep developing and become more severe over the years.

While many people are diagnosed with this disease, awareness around the disease is still minimal, say experts. On World Alzheimer's Day, FactChecker spoke to experts to debunk seven common myths about the condition.

Myth #1: Alzheimer's disease is only hereditary

Fact: Age, and not heredity, is the single most significant risk factor for developing Alzheimer's disease. According to the UK National Health Service (NHS), the likelihood of developing Alzheimer's disease doubles every five years after one turns 65.

A host of environmental and lifestyle factors beyond genetics — such as exercise, diet, exposure to pollutants, and smoking, affect a person's risk for Alzheimer's, according to the US National Institute for Aging (NIA).

"There are a few genes that are responsible for Alzheimer's disease. But the percentage of Alzheimer's disease which is transmitted genetically is very, very less," Dr Mohanakkannan, Consultant Neurologist, PSG Medical College and Hospital, Coimbatore, told FactChecker. "Majority of the people get the disease without family inheritance and due to degenerative processes," he explained.

Some other Alzheimer's related risk-factors are cardiovascular disease, mild cognitive impairment and traumatic brain injury.

Myth #2: Dementia and Alzheimer's are the same disease

Fact: Even though the terms Dementia and Alzheimer's are often used interchangeably, they are not the same. "Dementia is a general term for a decline in mental ability severe enough to interfere with daily life. Alzheimer's is the most common cause of dementia. Alzheimer's is a specific disease, unlike dementia," Dr Kersi Chavda, Consultant Psychiatrist, PD Hinduja Hospital & MRC, Mahim, told FactChecker.

Dementia causes more than usual forgetfulness (failing to identify friends, family, date and time), difficulty in communication, behaviour changes such as wandering, repeated questioning, and in some cases, aggression. There are many different forms of dementia, including Alzheimer's disease, which contributes between 60% to 70% of the total cases, according to the World Health Organization (WHO).

Other major forms include vascular dementia, dementia with Lewy bodies (abnormal aggregates of protein that develop inside nerve cells), and a group of diseases that contribute to frontotemporal dementia (degeneration of the frontal lobe of the brain).

Myth 3: Memory loss is the only symptom of Alzheimer's

Fact: Patients may experience many different symptoms of Alzheimer's, ranging from behavioural to cognitive, psychological to mood symptoms, and not just memory loss, said Dr Chavda.

The behavioural symptoms he listed were "aggression, agitation, difficulty with self-care, irritability, meaningless repetition of own words, personality changes, restlessness, lack of restraint, wandering and getting lost".

Common cognitive symptoms include "difficulty in thinking and understanding, confusion in the evening hours, delusion, disorientation, forgetfulness, making things up, mental confusion, difficulty concentrating, inability to create new memories, inability to do simple maths, or inability to recognise common things".

Mood swings, general discontent, and psychological symptoms such as depression, hallucinations or paranoia are also found in some patients, Dr Chavda elaborated.

Myth #4: Memory loss is a natural part of ageing

Fact: While many people may become more forgetful as they age, in Alzheimer's disease the cognitive deterioration that occurs is beyond what might be expected from the usual consequences of biological ageing. Essentially, if memory loss impacts one's day-to-day activities such as cleaning, dressing, and cooking, then it can be diagnosed as some form of dementia, explained Dr Mohanakkannan.

Also, patients of Alzheimer's may experience additional symptoms which are not linked to age-related memory loss, such as difficulty making decisions, getting lost in a familiar place, trouble handling money, repeating questions, etc. As the condition progresses, Alzheimer's patients even need assistance in completing day-to-day personal tasks.

Myth #5: Only older people can get Alzheimer's

Fact: Doctors say that although "early-onset Alzheimer's disease is rare, representing less than 10% of all people with Alzheimer's", it is still a possibility, Dr Chavda told FactChecker. It typically occurs between a person's 30s and mid-60s.

Most other people with Alzheimer's have the late-onset form of the disease, in which symptoms become apparent in one's mid-60s and later.

Myth #6: Alzheimer's can only be detected in the later stages

Fact: Recent research shows that higher-than-normal levels of a type of 'tau protein' and other cerebrospinal fluid markers were associated with a diagnosis of Alzheimer's disease in a diverse group of participants. So, the condition can be detected even before the symptoms start to set in, Dr Mohanakkannan mentioned.

"Till now, the only way to confirm that a person had Alzheimer's was by scanning the brain," said Dr Chavda. But now, "there is a blood test that reveals a strong link between elevated levels of a specific tau protein in the blood and the loss of nerve cells and impaired cognitive ability in Alzheimer's disease several years later."

Last month, scientists from Indian Institute of Technology, Jodhpur and other national research institutes in India developed another method that can be used to diagnose Alzheimer's disease. It comprises an efficient fluorescent molecular probe, which can enable rapid and safe analytical sensing due to the absence of radioactive chemicals or expensive equipment, reported Financial Express.

Myth #7: Alzheimer's can be cured

Fact: There's currently no cure for Alzheimer's disease. "All the treatments which are available are mainly supportive, which means they are memory enhancers, but the basic underlying degenerative process keeps going," Dr Mohanakkannan clarified. "No drug is available at present which can prevent, or stop, or reverse the cell death."

But there are medicines and treatment plans available that can temporarily improve the symptoms. Acetylcholinesterase (AChE) inhibitors increase levels of acetylcholine, a substance in the brain that helps nerve cells communicate with each other. Then there is Memantine that works by blocking the effects of an excessive amount of a chemical called glutamate in the brain.

"In the later stages of dementia, a significant number of people will develop what's known as behavioural and psychological symptoms of dementia. Here, one uses antipsychotics, benzodiazepines and mood stabilisers, and also antidepressants," said Dr Chavda.

In addition, having support systems and use of non-pharmacologic behavioural interventions can improve quality of life for people with different forms of dementia including Alzheimer's.