Mental Disorders of Old Age

Age is nothing but a number, so the saying goes.  But there are specific changes that our brains undergo as we grow older.  Structurally for instance, the brain shrinks otherwise referred to as brain atrophy.  In addition, there are chemical changes that accompany the structural changes.

Normal aging may be associated with age-associated memory loss.  This is however different from dementia as it does not interfere with the individual’s social or occupational functions.

Dementia is a progressive irreversible decline in intellectual functioning which affects how we think and behave.  The risk of dementia increases with age affecting 10- to 15% of those aged 75 and  25 to 35% of those aged 85 and older in the United States. We have no data for the Kenyan population.

The risk factors for dementia include age, female sex and history of dementia in the family. A brain chemical substance called Acetylcholine is reduced in dementia.

In dementia, previously achieved mental functions such as memory, language are lost gradually.  Behavioural disturbances include agitation, restlessness, wandering, violence and shouting.  Sexual disinhibition may lead them to strip, expose their genitals to unsuspecting strangers (exhibitionism) and may sexually assault children.  They may have false unshakable beliefs (delusions) or hear voices of imaginary people (hallucinations) which occur in 75% of these patients.  Depression occurs in 25-50% of patients with dementia.

Dementia types:

Dementia of the Alzheimer’s type: This is the most common type of dementia accounting for 50-60%.  It is commoner in females than males.  Initially the patient is unable to learn and recall new information, followed by inability to name items and copy figures.  They can tell childhood stories with ease but can’t remember what they had for the last meal.  Personality changes do occur; the patient may become obsessive, suspicious and may exhibit low moods.  Gait disturbances and inability to recognize objects using their shape do occur.  They also have sleep disturbances.

Vascular dementia:  Result from bleeding into the brain owing to blood vessel blockage and rupture.  Risk factors include hypertension, diabetes and cigarette smoking.

Other dementias result from:

-Parkinson’s disease (characterised by rigidity, slowness in movement and tremors which are worse at rest).

-Huntington’s disease:  Inherited disorder characterised by abnormal movements of the body (dance-like movement).

-H.I.V Associated dementia: H.I.V infection causes a diffuse loss of brain volume.  Opportunistic infections caused by an organism called Cryptococcus may cause dementia.