From letting dirty dishes pile up to feeling listless about a task at work, almost every-one lacks enthusiasm and motivation now and then.

But could longer-term apathy — a numbing loss of enthusiasm, emotion and drive — be a diagnosable health problem?

Traditionally, apathy has been seen as a sign of depression (and, ironically, can be a side-effect of some antidepressants). But scientists believe it could also be a key sign of dozens of other conditions, including stroke and heart disease.

They are also starting to get to the root of what causes extreme apathy in otherwise healthy people.

 ‘Many patients with apathy are wrongly labelled as just lazy. They are also misdiagnosed as having depression,’ says Professor Masud Husain, a neurologist at Oxford University. 

‘But while they may sit around all day doing very little, they can be happy, unlike people with depression.

‘It can be found in mild forms in healthy people. What seem a common feature are changes in certain areas of the brain.’

Last month, neurologists from the Royal Free Hospital in London reported that ‘apathy is an under-recognised and underestimated problem in people with chronic neurological disorders [eg, Parkinson’s].’

Despite being common and disabling, apathy was a problem that neither patients nor their carers tended to raise with their doctors, wrote researchers in the journal Practical Neurology.

They added that it’s important to distinguish apathy from depression because it requires different treatment, such as drugs other than antidepressants.

The neurologists defined apathy as reduced emotion (positive and negative), a lack of concern about symptoms, lack of motivation and emotional emptiness.

By comparison, they defined the key clues to depression as being sad, tearful or guilty, a sense of hopelessness about the future, variations in mood and so-called negative cognitive bias — in other words, seeing the worst side of everything.

The Royal Free researchers also noted that, unlike those with depression, people with apathy can occasionally be happy.

It is not the only research to suggest apathy is more than just part of depression. A 2009 study in the U.S. found that apathy was a symptom

It affected 29 per cent of older people with heart disease, up to 31 per cent of MS patients and 45 per cent of Parkinson’s patients.

It was also found in those with Lyme disease, chronic fatigue syndrome, testosterone deficiency and vitamin B12 deficiency.

The exact cause of apathy in these conditions is unclear, but the evidence points to changes in areas of the brain associated with reward — namely the prefrontal cortex (at the front of the brain) and the basal ganglia (a tiny area at the base of the brain).

For instance, research suggests that older people with heart disease may be affected by apathy because of reduced blood supply to these areas of the brain because their arteries are narrowed.

The role of the prefrontal cortex in apathy was identified by an Oxford University study published last month, which examined brain scans of healthy people.

It’s known that nearly all patients with frontotemporal dementia, which affects 16,000 people in Britain, suffer with apathy. This form of dementia, characterised by personality changes, affects the frontal lobes of the brain, which are involved in language and controlling behaviour and emotion.

The Oxford research, led by Professor Husain, found more activity in the frontal part of the brains of apathetic people.

For the study, 40 healthy volunteers carried out psychological tests while undergoing MRI scans. Those with apathetic traits had more activity in an area of the frontal lobes known as the pre-motor cortex, which is involved in controlling movement and so making us physically take action.

‘We expected to see less activity, but we found the opposite,’ says Professor Husain. ‘We thought this might be because their brain structure is less efficient, so it’s more of an effort for apathetic people to turn decisions into actions.

‘As far as we know, this is the first time anyone has found a biological basis for apathy in healthy people.

‘It doesn’t account for apathy in everyone, but by giving us more information about the brain processes underlying normal motivation, it helps us understand better how we might find a treatment for extreme apathy.’