Chemotherapy treatments for cancer may cause physical weakness due to changes in ability to think clearly and precisely, think and react speedily and may thus impair daily life activities, working memory, and organisational ability.
Chemotherapy induced brain fog has been recognised since the late 1980s, but the neurobiological reasons for it are still poorly understood.
Research has shown that certain drugs are more likely to cause it including: doxorubicin, cyclophosphamide, cytarabine, methotrexate, 5-fluorouracil and cisplatin. The drugs affect the central nervous system causing both physical weakness and mental confusion. The duration can be long or short. 35% of patients have an extended period of brain impairment. This can affect the validity of such legal issues as any will that is changed or undertaken during this period of time.
The sorts of impairments described are similar to those experienced with fibromyalgia and chronic fatigue syndrome.
Older patients seem to be more at risk of post chemo cognitive impairment compared to younger patients. If oestrogen and testosterone are depleted as well, such as with breast and prostate cancer treatments, the mental impairment is worse. Ongoing anxiety and depression also worsen the condition. Previous cancer treatments also have been shown to worsen mental impairment. It is not unusual for patients to have more than one cancer successfully treated. My comment: I had one very fit woman patient in her sixties who had been cured of five different unrelated tumours. As some of the treatments cause brain impairment but don’t cross the blood brain barrier it is thought that peripheral inflammatory cytokines have a role to play as well as other mechanisms.
Studies have found that in colon cancer, the brain impairment starts with the onset of the disease process, is worsened by chemotherapy and is worse the longer the treatment continues. The working memory, verbal learning and speed of information processing are all affected. As with other cancer patients these can go on to affect educational attainment and the ability to do certain jobs. Many countries classify cancer patients as having a disability for which reasonable adjustments need to be taken by the employer.
Legal contracts entered into by someone suffering from brain impairment due to cancer or cancer treatment may not be considered valid. It is up to a person who contests the validity of the agreement or contract to prove that the person was so impaired that they did not understand the implications of what their decision was. Certain age based factors such as appearing a little confused and disoriented cannot be considered symptomatic of testamentary inability, so the burden of proof is with the person contesting the contract.
My comment: We never know what is in front of us, so regular review of Power of Attorney, your will, and financial planning when you are healthy will make it easier for you and your relatives should you or your family be affected by cancer in the future.