1 Blame it on the seasons
Long associated with depression, apathy can be a symptom of Seasonal Affective Disorder (SAD), a form of depression characterised by a lack of enjoyment in life in the autumn and winter months. SAD tends to improve or even disappear during the summer. The Royal College of Psychiatrists says about three per cent of people will experience significant winter depression.
2 ...Or the 'manopause'
Some men develop a range of physical and emotional symptoms in their late 40s to 50s due to falling testosterone levels, including a loss of libido, a lack of energy and enthusiasm for life and difficulty concentrating.
3 You're stressed
Severe stress can cause burnout-related apathy, most commonly seen in post-traumatic stress disorder, which occurs after witnessing or enduring a dangerous event.
Sufferers may feel numbness or a loss of enjoyment in life. Experts believe the changes that cause PTSD-related apathy are likely to be a result of alterations in the brain triggered by the long-term circulation of stress hormones in the blood.
4 You need marmite
Vitamin B12 deficiency, sometimes known as folate deficiency anaemia, can cause depression, fatigue, memory loss and problems with learning and judgment. It is more common in old age and triggers can include some medications and a vegan diet. Marmite is fortified with B12.
5 It's anaemia
Lack of iron can result in anaemia, causing feelings of tiredness, apathy and irritability. In children, it can also lead to poor growth and development. In some women it can be put down to heavy periods or pregnancy. In other adults, it can be a result of bleeding from stomach ulcers.
6 Could you have Lyme disease?
Up to 20 per cent of people with Lyme disease - a bacterial infection spread to humans by tiny tick bites - go on to develop post-infectious Lyme disease, with symptoms including extreme tiredness, difficulty concentrating and brain fog.
7 ...Or heart disease?
Research has linked apathy to heart disease, suggesting older people with heart disease may become apathetic because narrowing arteries can result in reduced blood supply to the pre-frontal cortex, the part of the brain in charge of complex thought. Other symptoms of heart disease include chest pain and shortness of breath.
8 Brain drain
Can't be bothered to read on? It might be due to loose connections in your brain. An Oxford University study examined the pre-motor cortex (an area of the brain involved in taking action) in 40 healthy young people while they played games. It found that the area was less effective in apathetic people, and it was more of an effort for them to turn decisions into actions.
9 Drug-induced indifference?
Perversely, some people on anti-depressants known as selective serotonin reuptake inhibitors (SSRI) can suffer side effects such as feeling unfocused and demotivated. SSRIs work by increasing serotonin levels in the brain. However, studies have found that the brain attempts to compensate for the impact of the SSRIs by reducing its capacity to respond to serotonin in the first place, so increasing feelings of listlessness.
10 ...Or is it something more serious?
Apathy has been linked to a number of neurological conditions, including dementia, Parkinson's and Huntington's disease. A Norwegian study confirmed that apathy was a sign of worsening Parkinson's, while a rare type of dementia called frontotemporal dementia commonly leads to a lack of interest in life. But apathy alone is not a symptom of these conditions - patients would have a number of other physical or emotional symptoms.