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Abnormal mental states in multiple sclerosis

Dr Hugh Rickards, consultant in neuropsychiatry, Queen Elizabeth Psychiatric Hospital, Birmingham

Way Ahead 2003;7(1):6-7


"The mind is what the brain does" - Prof. Steven Pinker: How the mind works.

MS is primarily a disease of the brain. As this is where mental functions are controlled, it isn't surprising that changes in mental status are common in people with MS (PWMS).

However, mental disorders in MS are frequently overlooked for a number of reasons:

  • Changes in mental state are considered to be solely a 'reaction' to having a chronic illness
  • Many mental health services have retracted so they only treat 'functional' mental illnesses
  • The relatively few neurologists in the UK often restrict themselves to diagnostic issues and managing physical symptoms
  • Understanding symptoms of mental disorder is a complex process, often touching on personal and family issues. It can be easier to stick to the physical and practical aspects of care.

The burden of responsibility for mental illness in MS usually falls on relatives, carers and MS specialist nurses, who don't always feel adequately skilled to advise. This burden is heavy and may contribute to reduced quality of life in MS.

Practitioners need a number of skills to manage mental disorder in MS, including knowing how MS affects the brain, understanding the effects of prescribed and non-prescribed drugs on mental function and being able to recognise major mental disorders, such as depression, psychosis and cognitive impairment. Additional skills include understanding psychodynamic theory and "family systems" theory.

Depression in MS

Depression is a very common mental illness in MS. Around half of all PWMS will have clinical depression at some time, around three times the incidence in the general population. Depression in MS can sometimes be difficult to diagnose as many symptoms, such as fatigue, weight loss and lethargy, may occur in both conditions. Important clues in the diagnosis of depression include: pervasive low mood, sometimes with diurnal variation - often the mood is particularly bad in the morning; reduction in physical function that is disproportionate to their level of physical disability - level of physical disability does not correlate well with the risk of getting depression; and suicidal ideation. Suicidal ideas are quite common in PWMS who attend clinics, occurring in 25% at any one time. One study showed around 3% of PWMS will take their own lives, especially socially isolated young men with MS.

Transient low mood is normal in the period immediately after diagnosis and is known as adjustment disorder. Various common medications in MS, such as steroids, baclofen, dantrolene and interferon can cause changes in mood in either direction. Physical conditions, such as anaemia, vitamin deficiencies and thyroid disease can present with depression and need to be excluded.

Treating depression in MS is often rewarding and drugs in the Specific Serotonin Reuptake Inhibitor (SSRI) group are probably safest. Common side effects, usually transient, include nausea, sexual dysfunction and gastrointestinal disturbance. Withdrawal from these drugs should be gradual, especially with paroxetine (Seroxat).

Mania is relatively rare and, where it occurs, one should consider whether prescribed or non-prescribed drugs have been the trigger.

Paroxysmal emotional states

Paroxysmal emotional states are transient changes in behaviour or emotion, which resolve quickly. These are divided into pathological laughing and crying and emotional lability.

Pathological laughing and crying can occur in up to 10% of PWMS. The response can be to random stimuli and not related to how the person is feeling. Such laughing or crying may be short-lived (lasting only a few seconds) and is particularly seen in people with chronic MS with cognitive impairment. Pathological crying can be mistaken for depression but the mood is usually not pervasively low. Where it causes distress or disability treatment may be with amitryptilline, l-dopa or amantadine.

Emotional lability is characterised by an excessive emotional response to a minor stimulus, eg excessive emotional responses to soap operas on TV. Again the response is transient and has been described as 'an April shower'. Effective treatment has been described with carbamazepine and SSRIs.

Psychosis in MS

Psychotic symptoms - delusions, hallucinations and thought disorder - are uncommon in MS but extremely distressing. This may result in family breakdown and nursing home placement. Symptoms are similar to those seen in 'functional' psychoses such as schizophrenia, although visual hallucinations are more prominent and the mean age of onset (36 years) is later.

If a PWMS becomes psychotic (especially if there is acute onset) it is important to rule out physical triggers such as chest and urinary tract infections and metabolic disturbances. Steroids, baclofen and dantrolene have all been reported to trigger psychosis in people with MS so a close review of the treatment history is vital. People with severe depression may develop psychotic symptoms congruent with their mood - for instance delusions of poverty or guilt - and here treatment should be aimed at the depression. Finally, psychotic symptoms in MS may be the presenting feature of dementia.

People with MS are particularly sensitive to neuroleptic (anti-psychotic) medications. Rigidity and bradykinesia are commonly encountered even at low doses of conventional neuroleptics such as haloperidol. Therefore, atypical antipsychotics (quetiapine or olanzapine) should be first line therapy in this situation. The few studies about the prognosis of psychosis in MS suggest that treatment response is fair.

Cognitive changes

Many PWMS experience significant changes in cognitive function over time. Around 40% of PWMS in the community have some cognitive impairment. Typical problems include reduced speed of processing, reduced attention span and problems with executive function. Such problems may be the source of considerable disability but may not register on standard tests, such as the Folstein Mini Mental Status Examination or MMSE, or at clinical interview as verbal skills may be unaffected. Occupational therapy assessment at home is one of the best ways of detecting impairments in executive function. Specific tests that can reveal executive dysfunction include the Addenbrookes Cognitive Examination (ACE), the Frontal Assessment Battery (a short, sensitive, 'bedside' test) and the Behavioural Assessment of Dysexecutive Syndrome (BADS).

Conclusion

Mental status changes are extremely common in MS and are relatively neglected. They need thorough assessment with particular attention given to mood changes, cognition and perception. Many treatment or management strategies are effective.

There is a real danger that people with MS and mental illness will be excluded from services and it is vital that health professionals in neurology, psychiatry and rehabilitation work together to prevent this.